On phase equilibria and crystal structures in the systems Ce-Pd-B and Yb-Pd-B. Physical properties of R2Pd13.6B5 (R=Yb, Lu)

Article abstract of DOI:10.1016/j.jssc.2010.02.016

Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce-Pd-B and Yb-Pd-B at 850 °C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce-Pd-B system at 850 °C are governed by formation of extended homogeneity fields, τ₂-CePd₈B_2-x (0.103-Ce₃Pd_25-xB_8-y (1.063B_x (03. Crystallographic parameters for the new structure type τ₂-CePd₈B_2-x (space group C2/c, a=1.78104(4) nm, b=1.03723(3) nm, c=1.16314(3), β=118.515(1)° for x=0.46) were established from X-ray single crystal diffraction. The crystal structures of τ₂-CePd₈B_2-x and τ₃-Ce₃Pd_25-xB_3-y are connected in a crystallographic group-subgroup relationship. Due to the lack of suitable single crystals, the novel structure of τ₁-Ce₆Pd_47-xB₆ (x=0.2, C2/m space group, a=1.03594(2) nm, b=1.80782(3) nm, c=1.01997(2) nm, β=108.321(1)°) was determined from Rietveld refinement of X-ray powder diffraction data applying the structural model obtained from single crystals of homologous La₆Pd_47-xB₆ (x=0.19) (X-ray single crystal diffraction, new structure type, space group C2/m, a=1.03988(2) nm, b=1.81941(5) nm, c=1.02418(2) nm, β=108.168(1)°). The Yb-Pd-B system is characterized by one ternary compound, τ₁-Yb₂Pd₁₄B₅, forming equilibria with extended solution YbPd₃B_x, YbB₆, Pd₅B₂ and Pd₃B. The crystal structures of both Yb₂Pd₁₄B₅ and isotypic Lu₂Pd₁₄B₅ were determined from X-ray Rietveld refinements and found to be closely related to the Y₂Pd₁₄B₅-type (I4₁/amd). The crystal structure of binary Yb₅Pd_2-x (Mn₅C₂-type) was confirmed from X-ray single crystal data and a slight defect on the Pd site (x=0.06) was established. The three structures τ₁-Ce₆Pd_47-xB₆, τ₂-CePd₈B_2-x and τ₃-Ce₃Pd_25-xB_8-y are related and can be considered as the packings of fragments observed in Nd₂Fe₁₄B structure with different stacking of common structural blocks. Physical properties for Yb₂Pd_13.6B₅ (temperature dependent specific heat, electrical resistivity and magnetization) yielded a predominantly Yb-4f¹³ electronic configuration, presumably related with a magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the paramagnetic temperature domain.

Full text of DOI:10.1016/j.jssc.2010.02.016

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Journal of Solid State Chemistry 183 (2010) 1013–1037
Contents lists available at ScienceDirect
Journal of Solid State Chemistry
journal homepage: www.elsevier.com/locate/jssc
On phase equilibria and crystal structures in the systems Ce–Pd–B and
Yb–Pd–B. Physical properties of R2Pd13.6B5 (R¼Yb, Lu)$
Ã
Oksana Sologub a, Peter Rogl a, , Leonid Salamakha b, Ernst Bauer b, Gerfried Hilscher b,
Herwig Michor b, Gerald Giester c
a Institute of Physical Chemistry, University of Vienna, A-1090 Wien, Wa¨hringerstrasse 42, Austria
b Institute of Solid State Physics, Vienna University of Technology, A-1040 Wien, Austria
c Institute of Mineralogy and Crystallography, University of Vienna, Althanstr. 14, A-1090 Wien, Austria
a r t i c l e i n f o
a b s t r a c t
Article history:
Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce–Pd–B
and Yb–Pd–B at 850 1C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively,
employing X-ray single crystal and powder diffraction. Phase relations in the Ce–Pd–B system at
Received 12 December 2009
Received in revised form
11 February 2010
850 1C are governed by formation of extended homogeneity fields,
t2-CePd8B2ꢀx (0.10oxo0.48);
Accepted 20 February 2010
Available online 26 February 2010
t
3-Ce3Pd25ꢀxB8ꢀy (1.06oxo1.87; 2.20oyo0.05), and CePd3Bx (0oxo0.65) the latter arising from
binary CePd3. Crystallographic parameters for the new structure type t2-CePd8B2ꢀx (space group C2/c,
a¼1.78104(4) nm, b¼1.03723(3) nm, c¼1.16314(3),
X-ray single crystal diffraction. The crystal structures of
connected in a crystallographic group–subgroup relationship. Due to the lack of suitable single crystals,
the novel structure of
1-Ce6Pd47ꢀxB6 (x¼0.2, C2/m space group, a¼1.03594(2) nm, b¼1.80782(3) nm,
b
¼118.515(1)1 for x¼0.46) were established from
Keywords:
t
2-CePd8B2ꢀx and 3-Ce3Pd25ꢀxB3ꢀy are
t
Phase diagram
Crystal structure
t
X-ray powder and single crystal diffraction
Rare earth intermetallics
Crystal chemistry of intermetallics
Physical properties of Yb2Pd13.6B5
c¼1.01997(2) nm,
b¼108.321(1)1) was determined from Rietveld refinement of X-ray powder
diffraction data applying the structural model obtained from single crystals of homologous La6Pd47ꢀxB6
(x¼0.19) (X-ray single crystal diffraction, new structure type, space group C2/m, a¼1.03988(2) nm,
b¼1.81941(5) nm, c¼1.02418(2) nm,
b¼108.168(1)1).
The Yb–Pd–B system is characterized by one ternary compound, t1-Yb2Pd14B5, forming equilibria
with extended solution YbPd3Bx, YbB6, Pd5B2 and Pd3B. The crystal structures of both Yb2Pd14B5 and
isotypic Lu2Pd14B5 were determined from X-ray Rietveld refinements and found to be closely related to
the Y2Pd14B5-type (I41/amd). The crystal structure of binary Yb5Pd2ꢀx (Mn5C2-type) was confirmed
from X-ray single crystal data and a slight defect on the Pd site (x¼0.06) was established.
The three structures t1-Ce6Pd47ꢀxB6, t2-CePd8B2ꢀx and t3-Ce3Pd25ꢀxB8ꢀy are related and can be
considered as the packings of fragments observed in Nd2Fe14B structure with different stacking of
common structural blocks.
Physical properties for Yb2Pd13.6B5 (temperature dependent specific heat, electrical resistivity and
magnetization) yielded a predominantly Yb-4f13 electronic configuration, presumably related with a
magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the
paramagnetic temperature domain.
& 2010 Elsevier Inc. All rights reserved.
1. Introduction
has also motivated the search for novel superconducting states in
related ternary or quaternary alloy systems [4,5]. Similarly, a general
study of the formation of intermetallic borides and carbides AM3X
(A¼Mg, Ca, Sc, Y, Lu, Zr, Nb; M¼Ni, Ru, Rh, Pd, Pt with X¼B, C) [6]
raised our interest in the R–Pd–B systems particularly for R¼Ce, and
Yb as the two systems exhibit a complementary number of electrons
in the f-shell: one f-electron in Ce but one f-hole in Yb. Experimental
studies in the systems Ce–Pd–B and Yb–Pd–B hitherto have
concentrated mainly on the formation and characterization of
perovskite-type compounds RPd3Bx. Investigating the alloying
behavior of boron and RPd3 Dhar et al. [7] observed a valence
transition in Ce on the insertion of boron atoms into the voids of
The recent discovery of superconductivity in non-centrosym-
metric CePt3Si (CePt3B-type, i.e., a tetragonally distorted variant of
the CaTiO3 perovskite type [1,2]) as well as of BCS superconductivity
in MgNi3C with anti-perovskite type [3] has stimulated intensive
investigations not only in the field of perovskite intermetallics, but
$Dedicated to Prof. Dr. Ru¨diger Kniep on the occasion of his 65th birthday
Ã
Corresponding author. Fax: +43 1 4277 95245.
E-mail address: peter.franz.rogl@univie.ac.at (P. Rogl).
0022-4596/$ - see front matter & 2010 Elsevier Inc. All rights reserved.
doi:10.1016/j.jssc.2010.02.016

ARTICLE IN PRESS
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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
binary CePd3. Several studies were devoted to the physical property
changes in CePd3Bx depending on boron concentration [8–10] but
single crystal X-ray diffraction studies were performed only for
binary CePd3 confirming Ce atoms in the 1(a) site and Pd in the 3(c)
site of the AuCu3 type [11]. The lattice parameters reported are
slightly larger than those presented by Thomson [12] for Ce- and
Pd-rich members of the Ce1ꢀxPd3+x homogeneity field (0rxr
0.068, 0.4129ZaZ0.4112 nm) and agree well with the data given
by Bretschneider and Schaller (a¼0.41384 nm for x¼0.04 within
the homogeneity field ꢀ0.012rxr0.048) [13]. The insertion of
boron into interstitials of the CePd3 structure results in an increase
of the unit cell and causes a non-Vergard law-like behavior of
the lattice parameter variation, which was attributed to the
intermediate valence of the Ce ions. Transport measurements [14]
indicated that CePd3Bx with xr0.15 can be described as a Kondo
lattice but for the samples with x40.2 the behavior was found to be
completely different. It was suggested that this rearrangement is a
result of the valence shift from intermediate valence at x¼0 to a
valence of 3 at x¼0.3 [14]. For the Yb–Pd–B system, the information
available for more than two decades was limited to the experi-
mental data on the solubility of boron in YbPd3 [7].
diffraction lines was induced by the powdering process, the powders
of alloys with a content of 77–82 at% Pd were placed in molybdenum
containers, sealed in evacuated silica capsules and strain relieved for
30 min at 850 1C and quenched. Precise lattice parameters were
calculated by least squares fits to the indexed 2y values calibrated
with Ge as internal standard (aGe¼0.565791 nm). Single crystals
were mechanically isolated from the crushed as-cast and annealed
alloys. Inspections on an AXS-GADDS texture goniometer assured
high crystal quality, unit cell dimensions and monoclinic Laue
symmetry of the specimens prior to X-ray intensity data collections
on a four-circle Nonius Kappa diffractometer equipped with a CCD
area detector employing graphite monochromated MoK
a radiation
(l
¼0.071069 nm). Orientation matrices and unit cell parameters
were derived using the program DENZO [18]. No absorption
corrections were performed because of the rather regular crystal
shapes and small dimensions of the investigated specimens. The
structures were solved by direct methods and were refined with the
SHELXL-97 program [19,20]. Quantitative Rietveld refinements of
the X-ray powder diffraction data were performed with the
FULLPROF program [21]. Measurements of the various physical
properties were carried out with a series of standard techniques for
which details can be inquired from Ref. [4].
Recently, lattice parameters were presented for CePd3 and
‘‘CePd3B’’, calculated in the course of DFT (density functional
theory) electronic structure studies [15], although, the experi-
mental limit of boron incorporation in perovskite-type CePd3Bx
was established at 0oxo0.60 with a¼0.41935(1) nm for the
terminal composition [2]. The above mentioned studies [15]
performed by X-ray diffraction, energy dispersive and wavelength
dispersive X-ray spectroscopy also questioned the existence of
stoichiometric YbPd3B reported by Dhar et al. [7] and established
the limits of boron incorporation in YbPd3Bx at 0oxo0.45. The
significant range of homogeneity for binary YbPd3 ranging from
YbPd3.44(2) with a¼0.40317(4) to YbPd2.75(1) with a¼0.40506(3)
nm made an evaluation of the degree of boron filling solely based
on lattice parameter investigations difficult and questionable.
Moreover, within the density-functional theory using the LSDA+U
approximation a valence instability was established for YbPd3Bx
[15], for which the authors defined an experimental maximum of
boron solubility of 11 at% B (x¼0.45) at 1000 1C.
3. Results and discussion
3.1. Binary systems
The crystal data relevant to the unary and binary boundary
phases in the Ce–Pd–B and Yb–Pd–B systems are listed in Table 1.
Although several research groups have dealt with the phase
relations in the Ce–Pd system, there is still severe controversy
among the various versions of the phase diagram [12,13,24]. This
problem has not yet been resolved satisfactorily in the most recent
critical assessment by Okamoto [25]. Discrepancies mainly concern
(a) the stability range of CePd7, which for this work we take from
Bretschneider [13] and (b) the crystal structure of Ce3Pd5, which as
already mentioned by Thomson [12] does not correspond to the
Th3Pd5 structure. In agreement with a recent study of Ce–Pd–Si
[26], only the two cubic phases, CePd3 and CePd5 [27], were found
at 850 1C in the concentration region from 75 to 83at% Pd.
The phase diagram Yb–Pd was assessed by Okamoto [25]. A
recent study [15] established the limits of the YbPd3 homogeneity
field extending from YbPd3.44(2) to YbPd2.75(1) at 8001C. Within our
present cursory investigation X-ray powder data were analyzed for
several Yb–Pd alloys both in annealed and in as-cast conditions and
were found to be consistent with data in literature. As a single
crystal of good quality was found from the as-cast alloy Yb5Pd2 the
crystal structure was refined particularly as hitherto only isotypism
with the structure type of Mn5C2 has been stated from X-ray
photographs [38]. The structure refinement (R2F ¼0.035) confirmed
the Mn5C2-type with a small defect in one of the Pd-sites, which is
occupied for 96.9(4)% only, leading to an overall composition
Yb5Pd1.94. Results are compiled in Table 2. The Pd–B system used
herein is from a reinvestigation by the authors [40]. The low-
temperature ordering phases in the Pd-rich region [41] are not
relevant for the phase relations of the {Ce,Yb}–Pd–B ternary
systems at 850 1C. Both Ce–B and Yb–B binary phase diagrams
are accepted in the versions presented by Massalski [22].
In our search for novel materials with strong electron correla-
tions among rare earth metal–palladium–boride systems we herein
extended our studies to Ce(Yb)–Pd–B in the Ce(Yb)-poor region.
Recently, we reported on structural and physical properties for a
new series of palladium-rich compounds, M2Pd14+xB5–y (M¼Th, La,
Ce, Pr, Nd, Sm, Eu, Gd) [16] and on the crystal structures of
{La,Ce}3Pd25ꢀxB8ꢀy [17]. Aims of the present research are devoted
to (i) a detailed investigation of phase relations in the system
Ce–Pd–B and Yb–Pd–B up to 45 at% Ce and 34at% Yb, and
(ii) evaluation of the crystal structures of ternary compounds in
{Ce,Yb}–Pd–B and in the related systems with lutetium.
2. Experimental
All samples, each of a total amount of ca. 0.5 g, were prepared by
argon arc-melting ingots of rare earths (Alfa Aesar, purity 499.9
¨
mass%), palladium foil (Ogussa, 99.9%) and crystalline boron (Alfa
Aesar, 98%). For homogeneity, the samples were re-melted several
times. A part of each alloy was wrapped in Mo-foil, sealed in an
evacuated silica tube and heat-treated for 10 days at 850 1C prior to
quench by submerging the capsules in cold water. Alloys within the
ternary concentration field 24Ce:76Pd–12Ce:88Pd–10Ce:76Pd:14B
were annealed for 4 weeks at 850 1C. X-ray powder diffraction data
were collected employing a Guinier–Huber image plate system with
3.2. Ce–Pd–B system
3.2.1. Crystal structure of La6Pd47ꢀxB6 (x¼0.19) and
t
1-Ce6Pd47ꢀxB6 (x¼0.2)
monochromatic CuKa1 radiation (81o2
y
o1001) from as-cast and
The X-ray phase analysis of Ce–Pd–B alloys revealed a
annealed alloys. Alternatively, because significant broadening of
compound with hitherto unknown structure in the proximity of

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1015
Table 1
Crystallographic data of unary and binary boundary phases and ternary compounds of the systems Ce(Yb)–Pd–B.
Phase, temperature
Space group,
prototype
Lattice parameters (nm)
Comments
range (1C)
a
b
c
(
g
Ce)
798–726 [22]
Yb)
819–795 [22]
Yb)
0.412
–
–
[23]
Im3m
W
(
g
0.444
–
–
–
–
–
–
–
–
[23]
Im3m
W
0.5485
[23]
(
b
Fm3m
o795 [22]
(Pd)
Cu
0.38903
[23]
Fm3m
o1555 [22]
CexPd1ꢀx [13]
Cu
0.38902–0.39775
0rxr0.067 at 1000 1C [13]
Fm3m
Cu
0.38941
0.39060
0.39229
0.39295
0.39400
0.39775
–
x¼0.002 [13]
x¼0.013 [13]
x¼0.025 [13]
x¼0.030 [13]
x¼0.040 [13]
x¼0.068 (Pd)+Ce1ꢀxPd7+x [13]
YbxPd1ꢀx
–
–
0rxr0.165 at 900 1C [33]
Fm3m
o1555 [25]
Cu
0.3890–0.3965
0.3890–0.3935
–
0rxr0.12 [34]
0rxr0.08 [35]
0rxr0.195 at 850 1C [40]
for 0.144rxr0.177 [41]
[23]
PdBx [40]
PdBx
–
–
–
0.39913–0.40040
1.09251
2.38143
(
b
B)
o2092 [22]
-Ce1ꢀxPd7+x
1543–600 [13]
Rm3m
bB
–
–
–
[28]
b
Fm3m
CuPt7
0.8127–0.7955
0.79550
0.79688
0.80805
0.81221
0.81266
–
ꢀ0.024oxr0.184 at 1000 1C [13]
x¼0.184 [13]
x¼0.168 [13]
x¼0.040 [13]
x¼ ꢀ0.016 [13]
x¼ ꢀ0.024, CePd7+CePd5 [13]
ꢀ0.016oxo0.168 at 550 1C [13]
x¼0.168 CexPd1ꢀx+Ce1ꢀxPd7+x [13]
x¼0.04 [13]
a-Ce1ꢀxPd7+x
h
–
–
–
o600 [13]
0.2596
0.4048
0.4133
0.4169
0.2594
0.2593
x¼ ꢀ0.0156 Ce1ꢀxPd7+x+Ce1ꢀxPd3+x [13]
at 1000 1C [13]
CePd5
c
0.4055
1348–1060 [13]
h
–
–
[24]
b
-CePd5
1180–801 [24]
-CePd5 [24]
a
c
–
–
–
o801 1C [24]
[27]
o600 [27]
CePd5 [29]
Ce1ꢀxPd3+x
Pmma
c
0.57004
0.4056
0.5373
0.40622
0.84617
4700 1C[27]
[29]
P6/mmm
CaCu5
0.4177
0.4129–0.4112
–
Pm3m
o1437 [12]
Ce1ꢀxPd3+x [32]
AuCu3
–
0rxr0.068 [12] at 800 1C
ꢀ0.012rxr0.048 [13]
x¼0.04 [13]
0.41384
0.41231(1)–0.41131(9)
at 850 1C [this work]
CePd3By
–
0ryr0.60 at 800 1C [2]
Pm3m
–
CaTiO3
0.41935(1)
0.41694(4)
0.41954(5)
0.725
for y¼0.60 [2]
Ce1ꢀxPd3+xBy
y¼0.125 at 850 1C (this work)
y¼0.25 at 850 1C (this work)
Ce3Pd5
P-62m
0.385
–
[30]
o1037 [22]
Th3Pd5
–
–
unknown
[12, this work]
[31]
Ce3Pd4
1.3669
0.5824
R3m
o1130 [22]
YbPd7
Pu3Pd4
[34]
o448 [25]
Yb1ꢀxPd3+x
–
0rxr0.16 [25]
Pm3m
o1700 [38]
AuCu3
0.40317
for x¼0 at 900 1C [36,37]
0.4054–0.4040
0.40506–0.40317
0.4050–0.4088
[38]
ꢀ0.067rxr0.099 [15]
0rxr1 [7]
YbPd2.99(2)Bx [7]
Pm3m
CaTiO3
–
0rxr0.45 [15]
0.40938(2)
0.40990(5)
for x¼0.45(1) [15]
for x¼0.45, multiphase alloy
(this work)
[38]
–
b
-YbPd2
1382–1135 [38]

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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
Table 1 (continued )
Phase, temperature
Space group,
prototype
Lattice parameters (nm)
Comments
range (1C)
a
b
c
a
-Yb1ꢀxPd2+x
o113534
-Yb3Pd5
1360–1165 [38]
-Yb3Pd5
x¼0.041 [38]
[38]
b
a
o1155 [38]
Yb3Pd4
1.2900
0.5654
0.5578
[38]
R3m
o1415 [38]
Pu3Pd4
Pnma
FeB
0.7220
–
0.4123
0rxr0.06 [22,23]
–
b-Yb1ꢀxPdx
1460–1435 [38]
-YbPd
o1435 [38]
-Yb5Pd2
695–685 [38]
-Yb5Pd2
a
0.3440
0rxr0.06 [39]
Pm3m
CsCl
–
–
–
–
[38]
b
–
–
–
–
–
a
C2/c
Mn5C2
C2/c
Mn5C2
Pnma
Fe3C
1.6321
–
0.6550
0.7680
–
[38]
o685 [38]
Yb5Pd2ꢀx
–
b
¼97.531
1.63188(7)
0.65678(3)
0.76506(3)
x¼0.06 (this work)
b
¼97.317(2)1
Yb3Pd
0.7664
0.9678
0.6500
[38]
o670 [38]
Pd~4
B
[40,23]
[40,23]
[40,23]
[40,23]
[23]
1138–933 [40]
Pd3B
Pnma
Fe3C
0.5463
1.2786
0.46918
0.41396
0.7567
0.4955
0.4852
0.5472
0.31096
o1125 [40]
Pd5B2
C2/c
o1077 [40]
Pd2B
Mn5C2
Pnnm
CaCl2
b
¼97.031
0.51271
o994 [40]
CeB6
Pm3m
o2550 [22]
o2330 [25]
CeB4
CaB6
–
[25]
[23]
–
P4/mbm
0.7206
0.4090
o2380 [22]
o2165 [25]
YbB66
UB4
[25]
[23]
0.23422
0.7468
Fm3c
o2150 [22]
YbB12
YB65.86
[23]
[23]
Fm3m
o2200 [22]
YbB6
UB12
0.41479
Pm3m
o2300 [22]
CaB6
–
–
Yb1ꢀxB6+x
–
0rxr0.06 (this work)
at 850 1C (this work)
[23]
0.4127ꢀ0.4147
YbB4
P4/mbm
UB4
0.7064
0.3989
0.37315
1.01997(2)
–
o1850 [22]
YbB2
P6/mmm
AlB2
0.32503
1.03594(2)
–
[23]
o1500 [22]
Ce6Pd47ꢀxB6
C2/m
1.80782(3)
x¼0.19 at 850 1C (this work)
La6Pd47ꢀxB6
C2/c
b
¼108.321(1)1
CePd8B2ꢀx
–
0.08oxo0.48 at 850 1C
(this work)
CePd8B2ꢀx
1.7790(3)
–
1.0349(1)
¼118.54
1.03601(4)
1.1708(2)
–
boron rich (this work)
–
b
1.7803(1)
1.16152(6)
boron poor (this work)
b
–
¼118.75
Ce3Pd25ꢀxB8ꢀy
P21/c
–
–
1.06oxo1.88;
2.20oyo0.05 at 850 1C
(this work)
La3Pd25ꢀxB8ꢀy
–
–
–
boron rich (this work)
–
1.17274(3)
1.1734(4)
1.60271(4)
1.5966(5)
1.05537(2)
1.0455(2)
b¼102.265(1)1
boron poor (this work)
b
¼102.13(1)1
Yb2Pd13.6B5
I41/amd
0.83812(2)
1.66034(5)
(this work)
Nd2Pd14+xB5ꢀx -related
the composition 10Ce:80Pd:10B. Due to incongruent melting a
suitable single crystal specimen was only obtained from
homologous La-containing alloy. The crystal showed monoclinic
Laue symmetry 2/m with systematic extinctions compatible
with space group C2/m (no. 12). The initial atomic positions of
La and Pd atoms were deduced from direct methods, boron atoms
were located from difference Fourier synthesis. The difference
electron density map revealed additional peaks, which were
considered as split sites for Pd3 and Pd10. When allowed to refine
freely, the occupancies converged to 0.927Pd3/0.073Pd3a and
a

Table 2
Crystal structure dataa for Yb5Pd2ꢀx (x¼0.06) and R2Pd14ꢀxB5 compounds (R¼Yb, Lu).
Nominal composition
Space group
Structure type
Formula from refinement
Diffractometer
Theta range
Yb72.1Pd27.9
C2/c; no. 15
Mn5C2
Yb9.7Pd66.0B24.3
Lu9.9Pd65.3B24.8
I41/amd; no. 141
I41/amd; no. 141
Y2Pd14B5-related
Y2Pd14B5-related
Yb5Pd1.94
Yb2Pd13.6B5
Lu2Pd13.2B5
Nonius KappaCCD, MoK
a
Guinier–Huber image plate, CuKa1
Guinier–Huber image plate, CuKa1
3.351o2
y
o72.541
81o2
y
o1001
81o2
y
o1001
Crystal size
35 ꢁ 35 ꢁ 15
1.63188(7)
0.65678(3)
0.76506(3)
97.317(2)
m
m3
–
–
a (nm)
0.83812(2)
0.84173(4)
b (nm)
–
–
c (nm)
1.66034(5)
1.65761(8)
–
–
b
(deg)
Reflections in refinement
1456 Fo44
o0.4
s
(Fo) of 1905
216
–
218
–
Mosaicity
Number of variables
35
31
31
Reliability factors
R2F ¼
S
|F2o ꢀF2c|/
S
F2o ¼0.035;
RF¼
RI¼
S
|FoꢀFc|/
S
Fo¼0.033
RF¼
RI¼
S
|FoꢀFc|/
SFo¼0.073
–
–
S
|IoꢀIc|/
S
Io¼0.045
S
|IoꢀIc|/SIo¼0.062
–
RInt¼6.6
0.797
Rexp¼[(NꢀP+C)/
S
wiy2oi)]1/2¼1.05
Rexp¼[(NꢀP+C)/
S
wiy2oi)]1/2¼1.10
GOF
w2¼(RwP/Re)2¼33.6
w2¼(RwP/Re)2¼9.2
Extinction (Zachariasen)
R1;
0.00000(6)
–
–
8f (x,y,z); x¼0.21854(2),
y¼0.08127(6), z¼0.31712(5)
1.00 Yb, 0.01833(13)
8e (0,1/4,z); z¼0.0958(1)
8e (0,1/4,z); z¼0.0953(1)
–
–
b
Occ., Ueq (Biso
)
1.00 Yb, 0.97(7)
–
1.00 Lu, 0.88(9)
–
R2;
8f (x,y,z), x¼0.40865(3), y¼0.11467(6), z¼0.07897(5)
1.00 Yb, 0.01981(13)
Occ., Ueq
R3;
4e (0,y,1/4), y¼0.08445(8)
1.00 Yb, 0.01616(14)
–
–
Occ., Ueq
Pd1;
8f(x,y,z), x¼0.10876(5), y¼0.20415(12), z¼0.57881(9)
0.969(4) Pd, 0.01958(22)
–
16h (0,y,z); y¼0.0367(2), z¼0.2366(1)
1.00 Pd, 0.85(6)
16h (0,y,z); y¼0.0340(2), z¼0.2407(1)
1.00 Pd, 0.14(9)
Occ., Ueq (Biso
)
Pd2;
16h (0,y,z); y¼0.5861(2), z¼0.0667(1)
1.00 Pd, 0.35(6)
16h (0,y,z); y¼0.5917(2), z¼0.0644(1)
1.00 Pd, 0.78(9)
Occ., Biso
Pd3;
–
16g (x,x+1/4,7/8); x¼0.2922(2)
0.92(2) Pd, 0.77(6)
16g (x,x+1/4,7/8); x¼0.2969(2)
0.80(2) Pd, 0.83(11)
Occ., Biso
–
Pd4; Occ., Biso
–
8d (0,0,1/2); 1.00 Pd, 0.81(9)
16f (x,0,0); x¼0.204(2); 1.00B,0.80
4b (0,1/4,3/8); 1.00 B, 0.80
–
8d (0,0,1/2); 1.00 Pd, 0.98(10)
16f (x,0,0); x¼0.204(2); 1.00B,0.80
4b (0,1/4,3/8); 1.00 B, 0.80
–
B1; Occ.c, Biso
–
c
B2; Occ.c, Biso
–
c
Residual density; max; min (el./nm3) ꢁ 103
4.032; ꢀ2.342
Interatomic distances in [10 nm] for Yb5Pd1.94 (Mn5C2-type, space group C2/c; no. 15)
Yb1–Pd4
Yb1–Pd4
Yb1–Pd4
Yb1–Yb3
Yb1–Yb1
Yb1–2Yb1
Yb1–Yb2
Yb1–Yb2
Yb1–Yb2
Yb1–2Yb1
Yb1–Yb2
2.9635(8)
3.0357(8)
3.1608(8)
3.5379(4)
3.6146(8)
3.6279(4)
3.7028(6)
3.7990(6)
3.8408(6)
3.9714(3)
3.9846(6)
Yb1–Yb2
4.1992(6)
Yb2–Pd4
Yb2–Yb3
Yb2–Yb1
Yb2–Pd4
Yb2–2Yb2
Yb2–Yb1
3.4758(10)
3.9452(6)
3.9846(6)
4.0546(9)
4.1112(6)
4.1992(6)
Yb3–2Yb2
Yb3–2Yb2
Yb3–2Yb3
Pd4–2Yb2
Pd4–Yb1
Pd4–Yb3
Pd4–Yb3
Pd4–Yb1
Pd4–Yb1
Pd4–Yb2
Pd4–Yb2
3.6630(5)
3.9452(6)
3.9829(3)
2.9225(8)
2.9636(9)
2.9932(8)
3.0084(9)
3.0357(9)
3.1609(9)
3.4758(10)
4.0546(9)
Yb2–Pd4
Yb2–Pd4
Yb2–Yb3
Yb2–Yb3
Yb2–Yb2
Yb2–Yb1
Yb2–Yb2
Yb2–Yb1
Yb2–Yb1
2.9225(8)
2.9530(9)
3.5996(6)
3.6630(5)
3.6791(7)
3.7028(6)
3.7081(6)
3.7990(6)
3.8408(6)
Yb3–2Pd4
Yb3–2Pd4
Yb3–2Yb1
Yb3–2Yb2
2.9932(8)
3.0084(9)
3.5378(4)
3.5996(6)
a
Crystal structure data are standardized using the program Structure Tidy [42].
Atomic displacement parameters are given in [102 nm2].
Fixed parameters.
b
c

ARTICLE IN PRESS
1018
O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
0.927Pd10/0.072Pd10a constraining each split site to a total
occupancy of occ(Pd3+Pd3a)¼1 and occ(Pd10+Pd10a)¼1. All
other sites were found to be fully occupied except for Pd16
(occ 0.82), which is located too close to Pd3a and Pd10a. The split
positions as well as the boron atoms were refined with isotropic
3.2.2. Crystal structure of CePd8B2ꢀx
X-ray structure determinations were performed for two
crystals selected from as-cast and annealed alloys with different
content of boron within the homogeneity field (x1¼0.46,
x2¼0.32). The intensity patterns of both crystals indicated
monoclinic Laue symmetry and systematic extinctions, h+k¼2n
for (hkl) and l¼2n for (h0l), consistent with the C-centered space
groups Cc and C2/c. Intensity statistics favored the centrosym-
metric space group C2/c. Direct methods established the initial
positions of the Ce and Pd atoms. The atomic positions of boron
atoms were located from difference Fourier synthesis. The
structures were refined by full-matrix least-squares methods on
F2 with anisotropic displacement parameters for Ce and Pd atoms
but isotropic temperature factors for boron atoms (Table 4).
Refinements on the occupancy factors confirmed that in both
crystals all the sites are fully occupied except for atom site B2 and
thus resulted in the formulae CePd8B1.54 and CePd8B1.68. Final
difference Fourier maps revealed residual peaks as low as 2.81
and 4.13 (el./nm3) ꢁ 103, respectively. All atomic sites exhibit
reasonable atom displacement parameters except Pd12 for
which the thermal ellipsoid is elongated towards c-direction
and can be explained by the unusual coordination within the large
distorted tri-capped hexagonal antiprism with rather long
distances 0.27595(6) nm to the closest two neighboring Pd2
atoms (Fig. 3). For interatomic distances, the readers are kindly
displacement parameters.
A subsequent difference Fourier
synthesis revealed no significant residual peaks (residual electron
density o4.2 (el./nm3) ꢁ 103 at 0.070 nm from Pd9; see Table 3).
Space groups of lower symmetry (Cm, C2, P2/m, Pm, P2 and P-1)
were tested to ascertain if the disorder problems result from an
incorrect choice of space group with too high symmetry. In all
cases, the same features of split palladium sites persist and careful
re-examination of the CCD frames of the intensity data provided
no signs of superstructure reflections.
The distances between atoms and coordination polyhedra
are presented in Supplementary Data in Table 1 and in Fig. 1,
respectively. Due to split atomic sites (Pd3/Pd3a and Pd10/Pd10a),
which cannot be simultaneously occupied, two drawings of
coordination shells are shown for the atoms in contact. The
coordination polyhedra around both La sites are well defined.
La1 is surrounded only by palladium atoms, whereas the
coordination sphere of La2 includes, besides 17 palladium
atoms, one boron atom located against the rectangular face.
Typically for rare earth intermetallics with high metal content
(Th6Mn23, Mg2Zn11), the coordination polyhedra for lanthanum
atoms (CN 17 and 18 for La1 and La2, respectively) can be
deduced from the combination of pentagonal prisms and
pentagonal pyramids. The coordination numbers for palladium
atoms vary from CN 10 (cube with two additional atoms for
Pd16) to CN 16 for Pd13; in most cases, the coordination shells
for Pd atoms are icosahedra or their derivatives. The split atom
sites, Pd3a and Pd10a, which are occupied by 7.3% and 7.2%
each are coordinated by 11 atoms exhibiting shortened distances
to certain neighboring atoms (e.g., Pd3a–La2 0.2896(7) nm;
Pd3a–Pd10a 0.2083(8) nm; Pd3a–Pd3a 0.2031(7) nm). Analysis
of interatomic distances also showed that the proximity
of the Pd3, Pd10 and Pd16 atomic sites to those of Pd3a and
Pd10a precludes these positions from being simultaneously
occupied.
referred to Table
2 in Supplementary Data. All remaining
12 palladium atoms are in 12- to 16-fold coordination
exhibiting rather tight bonding with a shortest contact distance
dPd11–Pd13¼0.25588(5) nm (Fig. 4). The large Ce atoms occupy two
atomic sites, both with high coordination numbers of 18 (Ce1)
and 17 (Ce2). The Ce2 atom has only palladium neighbors. Ce–Pd
distances cover the range between dCe1–Pd3¼0.30130(6) nm and
dCe2–Pd10¼0.361(6) nm. There are only three boron positions, all
showing
a
trigonal-prismatic coordination as typical for
compounds of low-boron content. The rectangular faces of the
B3-centered prisms are capped with one Pd-atom. The distorted
triangular prisms centered by B1 and B2 also exhibit two and
three additional atoms around the waist of the rectangular faces
thus rendering the coordination geometry close to squared anti-
prismatic. The triangular prisms with B1 and B3 are paired via
common edges, and the coupling of B2 coordination polyhedra is
realized via rectangular faces. In agreement with the classification
of boride structure types based on the type of boron–boron
aggregation as a function of metal–boron ratio [43], no boron–
boron contacts were observed in the structure (Table 2,
Supplementary Data).
Two borons are coordinated by 7 (for B1) and 9 (for B2) metal
atoms. B1 is not placed exactly in the center of the triangular
palladium prism; it is shifted in
b direction towards the
rectangular face thus forming an additional contact with the
neighboring palladium atom. The Archimedean antiprism is
capped with one lanthanum atom displaying a large distance
dB–La¼0.3252(12) nm.
The complicated structure model obtained from the La-single
crystal was confirmed by Rietveld analysis of the X-ray powder
data for the Ce-isotype (Table 3, Fig. 1) exhibiting low residual
values and good agreement between calculated and observed
intensities. The X-ray powder diffraction spectrum taken from the
11Ce:79.5Pd:10.5B alloy resembled, in addition to the complex
As observed from X-ray Rietveld refinements, the CePd8B2ꢀx
phase (C2/c space group) exists at 850 1C within the concentration
region from 14 at% B to 17.5 at% B. The single crystal data
(CePd8B1.54, CePd8B1.68) show that the increase of boron content
in the structure is realized via an increase of the occupancy in the
B site. On reaching 17.5 at% B, the phase Ce3Pd25ꢀxB8ꢀy with
space group P21/c is formed which exhibits partly occupied
positions for certain palladium atoms as well as vacant B atom
sites (crystal with 18.2 at% B [17]). Further boron increase in the
structure which finally terminates at the boron-rich end of the
homogeneity field at 23 at% B (at 850 1C) is possible due to filling
vacant atomic positions with boron and by simultaneously
diminishing the occupancy of partly filled palladium sites.
pattern of t1, small amounts of foreign cubic phases for which
only the main reflections were detectable (Fig. 1, middle and low
rows of Bragg’s positions correspond to diffraction peaks from
unknown cubic phases; see also Table 6).
Fig. 2 shows the projections of the structure La6Pd47ꢀxB6
(x¼0.191) onto [001], [010] and [100] planes. The structure can
be considered as an arrangement of slabs in which four types of
polyhedra centered by Pd (Pd14 in 4f (1/4,1/4,1/2); Pd15 in 2d
(0,1/2,1/2); Pd16 in 2c (0,0,1/2) and Pd17 in 2a (0,0,0)) and
two types of polyhedra centered by boron (B1 in 8j (x, y, z)
x¼0.3588(7), y¼0.1796(4), z¼0.1056(7); B2 in 4i (x, 0, z);
x¼0.4019(10), z¼0.0913(11)) are packed such as to nearly
occupy the entire unit cell leaving unfilled voids with
dimensions too small to house an additional atom.
3.2.3. Crystal structure of the boron-rich end of the homogeneity
field Ce3Pd25ꢀxB8ꢀy
Attempts to establish (i) the upper boron limit of the
homogeneity field of Ce3Pd25ꢀxB8ꢀy and (ii) to estimate the
mechanism of boron uptake by the structure suffered from

ARTICLE IN PRESS
O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
1019
Table 3
Crystal structure data for R6Pd47ꢀxB6 (R¼La, Ce; new structure type, C2/m space group).
Nominal composition
Structure type
Formula from refinement
Range for data collection
Crystal size
La10.2Pd79.6B10.2
La6Pd47ꢀxB6
La6Pd47ꢀxB6 (x¼0.19)
Ce10.2Pd79.6B10.2
La6Pd47ꢀxB6
Ce6Pd47ꢀxB6 (x¼0.2)
2.09o
y
o36.30
81o2yo1001
45 ꢁ 35 ꢁ 35
1.03988(2)
1.81941(5)
1.02418(2)
108.168(1)
m
m3
Guinier–Huber image plate, CuKa1
a (nm)
1.03594(2)
1.80782(3)
1.01997(2)
108.321(1)
1093
b (nm)
c (nm)
b
(deg)
Reflections in refinement
Mosaicity
3173 Fo44
o0.4
151
s(Fo) of 4449
–
Number of variables
106
R2F ¼
–
S
|F2o ꢀF2c|/
S
Fo2
0.0333
–
RF¼
RI¼
Rexp¼[(NꢀP+C)/
S
|FoꢀFc|/
SFo¼0.048
S
|IoꢀIc|/SIo¼0.064
–
–
S
wiy2oi)]1/2¼1.06
GOF
1.027
0.00005(1)
w2¼(RwP/Re)2¼14.7
Extinction (Zachariasen)
R1a in 8j (x, y, z); occ.
0.28483(3), 0.35008(2), 0.26059(4); 1.00 La
0.2859(5), 0.3479(2), 0.2638(4); 1.0
Ce;
U11b, U22, U33, U23, U13, U12
;
0.0124(2), 0.0117(2), 0.0128(2), 0.0016(1), 0.0045(1), 0.0001(1)
–
c
Biso
–
0.87(8)
R2 in 4i (x, 0, z); occ.
0.21660(5), 0.29506(5); 1.00 La
0.0129(2), 0.0107(3), 0.0128(2), 0.0005(2)
–
0.2179(6), 0.2896(6); 1.0 Ce;
U11, U22, U33, U23¼U12¼0, U13
Biso
;
–
0.22(9)
Pd1 in 8j (x, y, z); occ.
0.02363(4), 0.12318(3), 0.14335(5); 1.00 Pd
0.0238(5), 0.1242(3), 0.1369(6);1.0
Pd;
–
U11, U22, U33, U23, U13, U12
;
0.0108(2), 0.0088(2), 0.0135(2), 0.0007(1), 0.0043(2),
ꢀ0.0006(2)–
Biso
–
0.61(8)
Pd2 in 8j (x, y, z); occ.
0.02882(4), 0.26488(3), 0.24735(5); 1.00 Pd
0.0326(5), 0.2655(3), 0.2490(5); 1.0
Pd;
–
U11, U22, U33, U23, U13, U12
;
0.0106(2), 0.0124(3), 0.0107(2), ꢀ0.0009(2), 0.0031(2),
0.0009(2)
Biso
–
0.76(9)
Pd4 in 8j (x, y, z); occ.
0.13054(5), 0.37873(3), 0.48401(5); 1.00 Pd
0.1266(6), 0.3773(3), 0.4828(5); 1.0
Pd;
U11, U22, U33, U23, U13, U12
;
;
0.0166(2), 0.0125(2), 0.0138(2), 0.0020(2), 0.0030(2), 0.0046(2)
–
Biso
–
0.62(8)
Pd5 in 8j (x, y, z); occ.
0.13589(4), 0.22913(3), 0.01870(4); 1.00 Pd
0.1336(5), 0.2286(3), 0.0216(5); 1.0
Pd;
–
U11, U22, U33, U23, U13, U12
0.0079(2), 0.0098(2), 0.0113(2), 0.0014(2), 0.0030(2),
ꢀ0.0001(1)
Biso
–
0.57(9)
Pd6 in 8j (x, y, z); occ.
0.23533(4), 0.08284(3), 0.02441(5); 1.00 Pd
0.2297(6), 0.0852(3), 0.0276(5); 1.0
Pd;
–
U11, U22, U33, U23, U13, U12
;
;
;
0.0087(2), 0.0101(2), 0.0102(2), ꢀ0.0000(1), 0.0022(2),
0.0006(2)
Biso
–
0.89(8)
Pd7 in 8j (x, y, z); occ.
0.27615(4), 0.17996(3), 0.26967(4); 1.00 Pd
0.2756(6), 0.1805(3), 0.2653(5); 1.0
Pd;
–
U11, U22, U33, U23, U13, U12
0.0115(2), 0.0123(2), 0.0089(2), ꢀ0.0001(2), 0.0035(2),
0.0010(2)
Biso
–
0.69(9)
Pd8 in 8j (x, y, z); occ.
0.46918(4), 0.07965(3), 0.24413(5); 1.00 Pd
0.4730(6), 0.0789(3), 0.2381(6); 1.0
Pd;
–
U11, U22, U33, U23, U13, U12
0.0111(2), 0.0104(2), 0.0114(2), ꢀ0.0003(2), 0.0017(2),
0.0006(2)
Biso
–
0.58(8)
Pd9 in 4i (x, 0, z); occ.
0.09647(7), 0.77586(7); 1.00 Pd
0.0874(7), 0.7625(7); 1.0 Pd;
U11, U22, U33, U23¼U12¼0, U13
Biso
;
;
;
;
0.0137(3), 0.0131(4), 0.0171(3), 0.0067(3)
–
–
0.98(14)
Pd11 in 4i (x, 0, z); occ.
U11, U22, U33, U23¼U12¼0, U13
Biso
0.61898(6), 0.11160(7); 1.00 Pd
0.6221(8), 0.1232(8); 1.0 Pd;
0.0119(3), 0.0097(3), 0.0178(3), 0.0065(3)
–
–
0.96(12)
Pd12 in 4h (0, y, 1/2); occ.
U11, U22, U33, U23¼U12¼0, U13
Biso
0.25094(4); 1.00 Pd
0.2504(4); 1.0 Pd;
0.0106(3), 0.0245(4), 0.0146(3), 0.0050(2)
–
–
0.95(10)
Pd13 in 4g (0, y, 0); occ.
U11, U22, U33, U23¼U12¼0, U13
Biso
0.36310(4); 1.00 Pd
0.3640(4); 1.0 Pd;
0.0128(3), 0.0088(3), 0.0124(3), 0.0043(2)
–
–
0.98(13)
1.0 Pd
–
Pd14 in 4f (1/4,1/4,1/2); occ.
1.00 Pd
U11, U22, U33, U23, U13, U12
;
0.0078(3), 0.0121(3), 0.0122(3), ꢀ0.0019(3)
0.0032(3), 0.0018(2)
Biso
0.69(11)
1.0 Pd
–
Pd15 in 2d (0,1/2,1/2); occ.
U11, U22, U33, U23¼U12¼0, U13
Biso
1.00 Pd
;
0.0126(4), 0.0092(5), 0.0147(5), 0.0030(3)
1.1(2)
0.8 Pd
Pd16 in 2c (0,0,1/2); occ.
0.819(3) Pd

ARTICLE IN PRESS
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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
Table 3 (continued )
U11, U22, U33, U23¼U12¼0, U13
Biso
;
;
0.0145(6), 0.0127(6), 0.0123(6), 0.0032(4)
–
–
1.2(3)
Pd17 in 2a (0,0,0); occ.
U11, U22, U33, U23¼U12¼0, U13
Biso
0.993(3) Pd
1.0 Pd
0.0104(4), 0.0068(5), 0.0113(5), 0.0048(3)
–
–
0.23(15)
Pd3 in 8j (x, y, z); occ.
0.09015(5), 0.12396(3), 0.41902(5); 0.927(1) Pd
0.091(1); 0.119(1); 0.423(1); 0.93 Pd;
–
U11, U22, U33, U23, U13, U12
;
0.0150(2), 0.0162(3), 0.0154(3), ꢀ0.0003(2), 0.0067(2),
ꢀ0.0016(2)
Biso
–
0.47(9)
Pd3a in 8j (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.06589(6), 0.07934(4), 0.44472(7); 0.073(1) Pd
0.059(9), 0.122(6), 0.396(9); 0.07 Pd;
–
;
0.0150(2), 0.0162(3), 0.0154(3), ꢀ0.0003(2), 0.0067(2),
ꢀ0.0016(2)
Biso
–
0.47(9)
Pd10 in 4i (x, 0, z); occ.
0.27211(8), 0.60882(8); 0.928(1) Pd
0.2733(9), 0.6037(10); 0.93 Pd;
U11, U22, U33, U23¼U12¼0, U13
Biso
;
;
0.0147(4), 0.0174(4), 0.0137(4), 0.0051(3)
–
–
0.76(11)
Pd10a in 4i (x, 0, z); occ.
U11, U22, U33, U23¼U12¼0, U13
0.1862(10), 0.5724(10); 0.072(1) Pd
0.231(10), 0.574(13); 0.07 Pd;
0.0147(4), 0.0174(4), 0.0137(4), 0.0051(3)
–
Biso
–
0.76(11)
B1 in 8j (x, y, z); occ.; Uiso
;
0.3588(7), 0.1796(4), 0.1056(7); 1.0 B; 0.014(1)
d0.3588, 0.1796, 0.1056; 1.0 B;
c
Biso
–
d1.0
B2 in 4i (x, 0, z); occ.; Uiso
0.4019(10), 0.0913(11); 1.0 B; 0.019(2)
–
d0.4019, 0.0913; 1.0 B;
Biso
d1.0
–
Residual electron density; max; min in (electrons/
nm3) ꢁ 1000
4.20; ꢀ2.89
a
Crystal structure data are standardized using the program Structure Tidy [42].
b
Anisotropic atomic displacement parameters Uij in [102 nm2]. The anisotropic temperature factor is defined as exp½ꢀ2p2ðU11h2aÃ2 þU22k2bÃ2 þU33l2cÃ2
þ
2U23klbÃcÃþ2U12hkaÃbÃþ2U13hlaÃcÃÞꢂ.
c
Isotropic atomic displacement parameters Uiso (Biso) in [102 nm2]. Uiso (Biso) values were obtained via isotropic refinement procedure.
d
Fixed parameter.
Fig. 1. X-ray diffraction pattern of Ce6Pd47ꢀxB6 (x¼0.2). The solid line derives from the Rietveld refinement. Yobs.ꢀYcalc. is the intensity difference between experimental
data and Rietveld calculations.
the fact that the monoclinic structure Ce3Pd25ꢀxB8ꢀy at higher boron
contents does not form directly from the melt, a fact which made
crystal growth difficult. Therefore single crystal structural studies
were performed on specimens obtained form a congruently
melting sample with about 25 at% B in the homologous system
with La. The structure solution by direct methods in space group
P21/c revealed three atomic positions of La and 24 Pd sites; the
atomic positions of boron atoms were found from difference
Fourier synthesis. The structure refinement arrived at the
arrangement of atomic sites and split positions (see Table 5) as
typical for the structure R3Pd25ꢀxB8ꢀy (R¼La, Ce) reported earlier
[17]. The virtual increase of boron content in the chemical
formula close to the boron-rich end of the homogeneity field as
compared to La3Pd25ꢀxB8ꢀy (x¼1.75, y¼0.07) essentially results
from a significant reduction of the occupancy of Pd25 in site 2a
(0,0,0) (from 71.2% Pd to 25.4% Pd) thus rendering the
composition La3Pd25ꢀxB8ꢀy (x¼1.88; y¼0.05) at almost no
variation of boron occupancy.
Transferring this structure model to Rietveld refinements of
XPD data in the boron-rich end of the homogeneity field for
Ce3Pd25ꢀxB8ꢀy allowed us to estimate the upper limit of boron
incorporation in the isotypic Ce-phase (see Table 5 and Fig. 5).
Though a full-profile Rietveld refinement cannot distinguish
between slight differences in the occupancies of palladium and
boron atoms, the low residual values and minor differences
between the observed and the calculated intensities for

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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
1021
Ce3Pd25ꢀxB8ꢀy confirmed the structure model obtained from the
La-crystal.
3.2.4. Phase equilibria at 850 1C
Phase analyses for selected samples are listed in Table 6
leading to the partial isothermal section at 850 1C as shown in
Fig. 6. In agreement with literature data, the CePd7 phase showed
a
rather large homogeneity region. Phase relations in the
concentration field from 67 to 75 at% Pd are governed by
formation of an extended solution CePd3Bx and three monoclinic
phases:
group C2/c) and
t
1-Ce6Pd47ꢀxB6 (space group C2/m),
t2-CePd8B2ꢀx (space
t3-Ce3Pd25ꢀxB8ꢀy (space group P21/c) [17]. The
two later compounds coexist in equilibrium at 850 1C and form a
homogeneity region extending from 14.5 to 23.8 at% B. Whilst the
C2/c monoclinic structure of the boron-poor end of the
homogeneity field is stable in the whole temperature interval,
the boron-rich structure with space group P21/c is limited to
lower temperatures. In as-cast condition the alloy Ce9.5Pd66.7B23.8
showed the X-ray powder diffraction spectrum characteristic for
the tetragonal Nd2Pd14+xB5ꢀx type [16] but after annealing at
850 1C the low temperature phase (P21/c) was observed. Fig. 7
summarizes the phase relations among the phases CePd8B2ꢀx
,
Ce3Pd25ꢀxB8ꢀy and Ce2Pd14+xB5ꢀy in a Tꢀx diagram as a function
of boron concentration. Lattice parameters as obtained from
Rietveld refinements and single crystal X-ray data for the phases
CePd8B2ꢀx and Ce3Pd25ꢀxB3ꢀy are shown in Fig. 8 as a function of
the boron concentration xB. For powder diffraction data, the
content of boron was taken from the nominal composition thus
explaining the small deviations from linearity for low boron
contents. Although there is a smooth general trend of lattice
parameters vs. xB, the monoclinic angle shows a significant
change manifesting
a
structural transition within the
homogeneity field on rising boron contents as it was also
inferred from Rietveld refinements and single crystal structural
analyses. Starting from the boron-poor end, the increasing boron
content (x) causes a slight increase of lattice parameters (Fig. 8).
Fig. 2. La6Pd47ꢀxB6 (x¼0.19) projected along crystallographic axes. Projection
along [100] shows the packing of Pd-centered and B-centered polyhedra.
Table 4
Single crystal structure data for CePd8B2ꢀx
.
Nominal composition
Space group
Ce9.49Pd75.93B14.58
C2/c; no. 15
Ce9.36Pd74.91B15.73
C2/c; no. 15
Structure type
Formula from refinement
Range for data collection
Crystal size
CePd8B2ꢀx
CePd8B2ꢀx
CePd8B2ꢀx (x¼0.46)
CePd8B2ꢀx (x¼0.32)
2.36o
y
o36.27
2.36oyo36.23
45 ꢁ 45 ꢁ 35
1.78104(4)
1.03723(3)
1.16314(3)
118.515(1)
m
m3
35 ꢁ 35 ꢁ 25
1.78277(4)
1.03626(3)
1.16172(3)
118.541(1)
m
m3
a (nm)
b (nm)
c (nm)
b
(deg)
Reflections in refinement
Mosaicity
3627 Fo44
o0.4
140
s(Fo) of 4348
3360 Fo44
o0.4
140
s(Fo) of 4435
Number of variables
R2F ¼
RInt
S
|F20ꢀF2c|/
S
F02
0.0272
0.0359
GOF
0.769
0.815
Extinction (Zachariasen)
Ce1a in 8f (x, y, z); occ.
U11b, U22, U33, U23, U13, U12
0.00013(2)
0.00000(2)
0.34719(2), 0.42582(4), 0.22263(3); 1.00 Ce
0.0103(2), 0.0106(2), 0.0109(2), ꢀ0.0001(1), 0.0049(1),
0.0002(1)
0.34694(3), 0.42580(4), 0.22265(4); 1.00 Ce
0.0096(2), 0.0103(2), 0.0103(2), ꢀ0.00012(14), 0.0046(1),
0.00013(13)
Ce2 in 4e (0, y, 1/4); occ.
U11, U22, U33, U23¼U12¼0, U13
Pd1 in 8f (x, y, z); occ.
0.37382(5); 1.00 Ce
0.37422(6); 1.00 Ce
0.0105(2), 0.0096(2), 0.0120(2), 0.0046(2)
0.07949(3), 0.24031(5), 0.52225(5); 1.00 Pd
0.0097(2), 0.0132(2), 0.0129(2), 0.0002(2), 0.0057(2),
ꢀ0.0004(2)
0.0100(2), 0.0087(2), 0.0115(2), 0.0045(2)
0.07907(3), 0.24070(6), 0.52206(6); 1.00 Pd
0.0096(2), 0.0144(3), 0.0118(2), 0.0000(2), 0.0056(2),
ꢀ0.0007(2)
U11, U22, U33, U23, U13, U12
Pd2 in 8f (x, y, z); occ.
0.09128(3), 0.19372(5), 0.14004(4); 1.00 Pd
0.0096(2), 0.0105(2), 0.0092(2), ꢀ0.0003(1), 0.0036(1),
ꢀ0.0010(1)
0.09145(3), 0.19393(5), 0.14022(5); 1.00 Pd
0.0087(2), 0.0106(2), 0.0080(2), ꢀ0.0000(2), 0.0031(2),
ꢀ0.0010(2)
U11, U22, U33, U23, U13, U12
Pd3 in 8f (x, y, z); occ.
0.16802(3), 0.00598(5), 0.04036(5); 1.00 Pd
0.16803(3), 0.00627(5), 0.04041(6); 1.00 Pd

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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
Table 4 (continued )
U11, U22, U33, U23, U13, U12
0.0117(2), 0.0108(2), 0.0122(2), 0.0008(1), 0.0062(1),
0.0014(1)
0.0121(2), 0.0105(2), 0.0116(2), 0.0003(1), 0.0066(2),
0.0015(2)
Pd4 in 8f (x, y, z); occ.
0.17307(3), 0.20562(5), 0.39913(5); 1.00 Pd
0.0119(2), 0.0109(2), 0.0127(2), 0.00003(16), 0.0060(1),
0.0013(1)
0.17296(3), 0.20545(5), 0.39981(6); 1.00 Pd
0.0108(2), 0.0104(2), 0.0126(2), ꢀ0.00003(2), 0.0057(2),
0.0010(2)
U11, U22, U33, U23, U13, U12
Pd5 in 8f (x, y, z); occ.
0.17817(3), 0.41844(5), 0.24145(4); 1.00 Pd
0.0110(2), 0.0093(2), 0.0114(2), ꢀ0.0007(1), 0.0048(1),
ꢀ0.0005(1)
0.17826(3), 0.41885(5), 0.24164(6); 1.00 Pd
0.0099(2), 0.0087(2), 0.0113(2), ꢀ0.0007(1), 0.0048(2),
ꢀ0.0005(2)
U11, U22, U33, U23, U13, U12
Pd6 in 8f (x, y, z); occ.
0.18940(3), 0.27726(5), 0.03093(5); 1.00 Pd
0.0085(2), 0.0108(2), 0.0111(2), 0.0013(1), 0.0050(1),
0.0014(1)
0.18945(3), 0.27768(5), 0.03082(5); 1.00 Pd
0.0079(2), 0.0106(2), 0.0105(2), 0.0013(2), 0.0048(2),
0.0014(2)
U11, U22, U33, U23, U13, U12
Pd7 in 8f (x, y, z); occ.
0.26920(3), 0.16904(5), 0.27259(4); 1.00 Pd
0.0087(2), 0.0111(2), 0.0100(2), 0.0008(1), 0.0045(1),
0.0008(1)
0.26915(3), 0.16988(5), 0.27304(5); 1.00 Pd
0.0080(2), 0.0107(2), 0.0094(2), 0.0007(2), 0.0039(2),
0.0007(2)
U11, U22, U33, U23, U13, U12
Pd8 in 8f (x, y, z); occ.
0.31991(3), 0.04361(5), 0.51182(4); 1.00 Pd
0.0111(2), 0.0092(2), 0.0106(2), 0.0003(1), 0.0045(1),
0.0010(1)
0.31975(3), 0.04361(5), 0.51186(5); 1.00 Pd
0.0103(2), 0.0093(2), 0.0100(2), 0.0000(2), 0.0042(2),
0.0011(2)
U11, U22, U33, U23, U13, U12
Pd9 in 8f (x, y, z); occ.
0.41076(3), 0.13363(5), 0.23078(4); 1.00 Pd
0.0097(2), 0.0099(2), 0.0104(2), 0.0003(1), 0.0050(1),
ꢀ0.00002(1)
0.41056(3), 0.13369(5), 0.23071(5); 1.00 Pd
0.0095(2), 0.0095(2), 0.0095(2), 0.0005(2), 0.0051(2),
ꢀ0.0004(2)
U11, U22, U33, U23, U13, U12
Pd10 in 8f (x, y, z); occ.
0.45713(3), 0.09026(5), 0.02179(5); 1.00 Pd
0.0092(2), 0.0095(2), 0.0115(2), ꢀ0.0008(1), 0.0045(1),
0.0012(1)
0.45693(3), 0.08983(5), 0.02190(6); 1.00 Pd
0.0089(2), 0.0097(2), 0.0112(2), ꢀ0.0008(2), 0.0047(2),
0.0011(2)
U11, U22, U33, U23, U13, U12
Pd11 in 8f (x, y, z); occ.
0.46607(3), 0.32675(5), 0.12499(4); 1.00 Pd
0.0109(2), 0.0101(2), 0.0083(2), 0.0003(1), 0.0039(1),
ꢀ0.0003(1)
0.46601(3), 0.32664(5), 0.12482(5); 1.00 Pd
0.0105(2), 0.0101(2), 0.0078(2), 0.0006(2), 0.0038(2),
ꢀ0.0001(2)
U11, U22, U33, U23, U13, U12
Pd12 in 4e (0, y, 1/4); occ.
U11, U22, U33, U23¼U12¼0, U13
Pd13 in 4a (0,0,0); occ.
0.07942(8); 0.995(3) Pd
0.07947(9); 1.007(4) Pd
0.0297(4), 0.0120(3), 0.0497(5), 0.0323(4)
1.00 Pd
0.0276(5), 0.0117(4), 0.0457(6), 0.0301(5)
1.00 Pd
U11, U22, U33, U23, U13, U12
0.0108(3), 0.0086(3), 0.0149(3), 0.0008(2), 0.0053(2),
ꢀ0.0018(2)
0.0105(3), 0.0092(3), 0.0144(4), 0.0005(3), 0.0052(3),
ꢀ0.0026(2)
B1 in 8f (x, y, z); occ.
0.2776(7), 0.113(1), 0.098(1); 1.00 Bd
0.033(2)
0.2785(8), 0.113(1), 0.097(1); 1.00 Bd
0.032(2)
c
Uiso
B2 in 8f (x, y, z); occ.
Uiso
0.279(1), 0.313(2), 0.408(2); 0.31(2) B
0.004(3)
0.3956(5), 0.0714(8), 0.4014(7); 1.00 Bd
0.016(1)
0.274(1), 0.315(2), 0.409(2); 0.52(3) B
0.012(5)
0.3958(6), 0.0711(9), 0.4002(9); 1.00 Bd
0.017(2)
B3 in 8f (x, y, z); occ.
Uiso
Residual electron density; max;
min in (electrons/nm3) ꢁ 1000
2.81; ꢀ2.09
4.13; ꢀ2.36
a
Crystal structure data are standardized using the program Structure Tidy [42].
2
2
2
Ã
b
Anisotropic atomic displacement parameters Uij in [102 nm2]. The anisotropic temperature factor is defined as exp½ꢀ2p2ðU11h2a þU22k2b þU33l2c
þ
Ã
Ã
2U23klbÃcÃþ2U12hkaÃbÃþ2U13hlaÃcÃÞꢂ.
c
Isotropic atomic displacement parameters Uiso in [102 nm2]. Uiso values were obtained via isotropic refinement procedure.
d
Fixed parameter.
Fig. 3. CePd8B2ꢀx structure projected along the monoclinic axis (left panel) and along z-axis (right panel). Coordination polyhedra of boron and Pd12 atoms are
emphasized. The atoms are represented by their thermal ellipsoids.
This trend is consistent with the results of structural investi-
gations for two different crystals of CePd8B2ꢀx where the atomic
positions of boron are occupied at 31(2)% and 52(3)% while the
palladium content remains constant (Table 4). At about 18.3 at%
of B, the formation of the Ce3Pd25ꢀxB8ꢀy-type structure (x¼1.25,
y¼2.00) was observed from X-ray single crystal data [17] revealing
partially occupied atomic sites of palladium. With further increase
of boron content, the phase arrives at the boron-rich terminus of
the homogeneity field with a continuous decrease of palladium
occupancy at certain Pd-sites and a simultaneous enhancement of
the occupancy in the boron sites (see Rietveld refinement for
Ce3Pd25ꢀxB8ꢀy (x¼1.87; y¼0.05) in Table 5).
Lattice constants for binary CePd3 show the existence of a
small homogeneity field and agree well with those reported in

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1023
literature: data after Thomson [12] (0.4129–0.4112 nm) compare
well with our experiments for stoichiometric and Pd-rich
compositions (0.41231(1)–0.41131(9) nm), respectively. Compo-
sitional dependences of lattice parameters for CePd3Bx observed
in our experiments (Fig. 9) revealed a significant expansion of the
unit cell even for the alloy CePd3B0.125 saturating after reaching
the maximum value a¼0.41954(5) nm at CePd3B0.25. Judging from
phase analysis, single-phase alloys CePd3Bx were found within the
range 0rxo0.65. Thus the limit of boron incorporation in CePd3
was established at 13 at% in agreement with recent results [2].
Phase equilibria for concentrations o66 at% Pd are dominated by
CeB4 and CeB6, which coexist with Pd2B, Pd5B2, Ce3Pd25ꢀxB3ꢀy
and CePd3Bx. The X-ray powder diffraction pattern observed for
Ce3Pd5 does not agree with the spectrum calculated for the
Th3Pd5 type [30]. The evaluation of the phase field
CeB4+CePd3Bx+Ce3Pd5 from lattice parameter variations has
been guided not only by the non-stoichiometry of CePd3Bx but
by the existence of a certain homogeneity field for the CePd3
binary as well.
3.3. Structural analysis
The X-ray single crystal and powder diffraction study revealed
the existence of three different monoclinic structures in the
palladium-rich corner of the Ce–Pd–B system. The phase
CePd8B2ꢀx (for x¼0.46 and 0.32) crystallizes in the space group
C2/c while for the remaining two phases the symmetry is
reduced: for R3Pd25ꢀxB8ꢀy and La6Pd47ꢀxB6, respectively (R¼La,
Ce) the space groups P21/c and C2/m were established. All of them
belong to the point group 2/m. The space group P21/c is a
klassengleiche subgroup of index 2 of C2/c and arises through the
loss of Bravais translation symmetry. The formal group–subgroup
Fig. 4. Coordination polyhedra in the CePd8B2ꢀx structure.
Table 5
Crystal structure data for the boron-rich members of the homogeneity field R3Pd25ꢀxB8ꢀy (R¼La, Ce; space group P21/c (no. 14); structure type La3Pd25ꢀxB8ꢀy).
Nominal composition
Formula from refinement
Range for data collection
Diffractometer
Crystal size
La8.8Pd67.8B23.4
Ce8.8Pd67.9B23.3
La3Pd25ꢀxB8ꢀy (x¼1.88(1); y¼0.05(1))
Ce3Pd25ꢀxB8ꢀy (x¼1.87; y¼0.05)
2.32o
y
o36.29
81o2yo1001
Nonius KappaCCD, MoK
a
Guinier–Huber image plate, CuKa1
45 ꢁ 40 ꢁ 40
1.17703(2)
1.05950(2)
1.60981(3)
102.121(1)
m
m3
–
a (nm)
1.17274(3)
1.05537(2)
1.60271(4)
102.265(1)
2351
b (nm)
c (nm)
b
(deg)
Reflections in refinement
Mosaicity
6886 Fo44s(Fo) of 9236
o0.4
283
–
Number of variables
133
R2F ¼
S
|F2o ꢀF2c|/
S
Fo2
0.0314
1.019
RF¼
RI¼
S
|FoꢀFc|/
SFo¼0.061
GOF
S|IoꢀIc|/SIo¼0.056
Rexp¼[(NꢀP+C)/
S
wiy2oi)]1/2¼1.61
w2¼(RwP/Re)2¼2.27
RInt
–
Extinction (Zachariasen)
R1a in 4e (x, y, z); occ.
0.00013(1)
–
0.13407(3), 0.56656(4), 0.34960(3); 1.00 La
0.0088(1), 0.0099(2), 0.0105(1), ꢀ0.0008(1),
0.0018(1), 0.0000(1)
0.1465(9), 0.53(1), 0.3614(9); 1.00 Ce;
U11b, U22, U33, U23, U13, U12
–
–
c
Biso
–
0.9(3)
R2 in 4e (x, y, z); occ.
0.24378(3), 0.37245(3), 0.00087(2); 1.00 La
0.0149(1), 0.0094(2), 0.0098(2), ꢀ0.002(1),
0.0024(1), 0.0005(1)
0.255(1), 0.378(1), 0.0008(12); 1.00 Ce;
U11, U22, U33, U23, U13, U12
–
–
Biso
–
0.7(3)
R3 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.63199(3), 0.41179(4), 0.32954(3); 1.00 La
0.0085(2), 0.0106(2), 0.0111(2), 0.0014(1),
0.0015(1), ꢀ0.0006(13)
0.610(2), 0.410(1), 0.3265(9); 1.00 Ce;
–
–
Biso
–
0.6(3)
Pd1 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.00184(5), 0.34010(5), 0.23079(3); 1.00 Pd
0.0087(2), 0.0106(2), 0.0112(2), 0.0000(1),
0.0020(2), 0.0003(2)
0.014(1), 0.34(2), 0.234(1); 1.00 Pd;
–
–
Biso
–
0.5(3)
Pd2 in 4e (x, y, z); occ.
0.03705(5), 0.31543(7), 0.41060(4); 1.00 Pd
0.038(1), 0.306(2), 0.407(1); 1.00 Pd;

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Table 5 (continued )
U11, U22, U33, U23, U13, U12
0.0144(3), 0.0260(3), 0.0150(3), 0.0079(2),
ꢀ0.0009(2), ꢀ0.0066(2)
–
–
Biso
–
0.2(4)
Pd3 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.05200(5), 0.23530(5), 0.08706(3); 1.00 Pd
0.0104(2), 0.0134(2), 0.0105(2),
0.0011(2),0.0020(2),0.0020(2)
–
0.060(1), 0.224(1), 0.082(1); 1.00 Pd;
–
–
Biso
0.6(4)
Pd4 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.05777(5), 0.08951(5), 0.32512(4); 1.00 Pd
0.0127(2), 0.0133(3), 0.0128(2), 0.0023(2),
0.0029(2), ꢀ0.0011(2)
0.073(1), 0.099(2), 0.3194(9); 1.00 Pd;
–
–
Biso
–
0.9(4)
Pd5 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.06232(5), 0.59425(5), 0.04081(3); 1.00 Pd
0.0107(2), 0.0095(2), 0.0085(2), ꢀ0.0008(2),
0.0017(2), ꢀ0.0016(2)
0.065(1), 0.584(1), 0.049(1); 1.00 Pd;
–
–
Biso
–
0.5(3)
Pd6 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.12404(5), 0.50086(5), 0.67403(4); 1.00 Pd
0.0098(2), 0.0102(2), 0.0142(2), ꢀ0.0020(2),
0.0033(2), ꢀ0.0004(2)
0.142(2), 0.515(1), 0.6853(9); 1.00 Pd;
–
–
Biso
–
0.3(1)
Pd7 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.16269(4), 0.72456(5), 0.19062(3); 1.00 Pd
0.0086(2), 0.0094(2), 0.0087(2), ꢀ0.0007(2),
0.0008(2), 0.0009(2)
0.179(1), 0.719(1), 0.188(1); 1.00 Pd;
–
–
Biso
–
0.3(2)
Pd8 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.17258(5), 0.82438(6), 0.02799(4); 1.00 Pd
0.0145(2), 0.0134(2), 0.0113(2), ꢀ0.0000(1),
0.0023(2), ꢀ0.0040(2)
0.181(1), 0.824(2), 0.0363(9); 1.00 Pd;
–
–
Biso
–
0.8(3)
Pd9 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.19167(5), 0.45620(5), 0.17826(3); 1.00 Pd
0.0118(2), 0.0093(2), 0.0109(2), 0.0001(2),
0.0025(2), ꢀ0.0000(2)
0.183(1), 0.450(1), 0.193(1); 1.00 Pd;
–
–
Biso
–
0.6(2)
Pd11 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.22375(5), 0.28997(5), 0.33113(4); 1.00 Pd
0.0096(2), 0.0103(2), 0.0132(2), 0.0017(2),
0.0019(2), ꢀ0.0003(2)
0.225(1), 0.277(1), 0.332(1); 1.00 Pd;
–
–
Biso
–
0.4(3)
Pd12 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.27622(5), 0.20396(5), 0.18037(3); 1.00 Pd
0.0086(2), 0.0108(2), 0.0104(2), 0.0004(2),
0.0016(2), 0.0001(2)
0.281(1), 0.193(2), 0.179(1); 1.00 Pd;
–
–
Biso
–
0.5(3)
Pd13 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.30923(5), 0.03496(5), 0.32618(3); 1.00 Pd
0.0117(2), 0.0092(2), 0.0105(2), 0.0008(2),
0.0022(2), 0.0003(2)
0.309(2), 0.023(2), 0.337(1); 1.00 Pd;
–
–
Biso
–
0.6(2)
Pd14 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.32134(5), 0.62454(5), 0.09336(3); 1.00 Pd
0.0101(2), 0.0119(2), 0.0092(2), ꢀ0.0003(2),
0.0023(2), ꢀ0.0005(2)
0.316(1), 0.627(2), 0.090(1); 1.00 Pd;
–
–
Biso
–
0.6(3)
Pd15 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.38115(5), 0.48399(5), 0.32659(3); 1.00 Pd
0.0104(2), 0.0088(2), 0.0110(2), 0.0005(2),
0.0032(2), 0.0005(2)
0.391(1), 0.479(2), 0.330(1); 1.00 Pd;
–
–
Biso
–
0.5(2)
Pd16 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.43828(5), 0.17214(5), 0.07600(3); 1.00 Pd
0.0124(2), 0.0118(2), 0.0106(2), ꢀ0.0009(2),
0.0037(2), ꢀ0.0002(2)
0.427(1), 0.164(2), 0.077(1); 1.00 Pd;
–
–
Biso
–
0.8(3)
Pd17 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.44012(5), 0.39728(5), 0.16865(5); 1.00 Pd
0.0131(2), 0.0104(2), 0.0101(2), ꢀ0.0000(2),
0.0032(2), ꢀ0.0018(2)
0.445(2), 0.394(1), 0.1728(9); 1.00 Pd;
–
–
Biso
–
0.8(4)
Pd18 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.45269(5), 0.25380(5), 0.40857(3); 1.00 Pd
0.0118(2), 0.0092(2), 0.0087(2), 0.0007(2),
0.0017(2), 0.0007(2)
0.449(1), 0.250(1), 0.400(1); 1.00 Pd;
–
–
Biso
–
0.6(2)
Pd19 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.50150(5), 0.14776(5), 0.26252(3); 1.00 Pd
0.0085(2), 0.0098(2), 0.0104(2), ꢀ0.0010(2),
0.0014(2), 0.0003(2)
0.503(1), 0.149(2), 0.267(1); 1.00 Pd;
–
–
Biso
–
0.5(2)
Pd20 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.56102(5), 0.40071(5), 0.03421(3); 1.00 Pd
0.0107(2), 0.0100(2), 0.0075(2), ꢀ0.0000(2),
0.0011(2), 0.0010(2)
0.562(1), 0.396(2), 0.035(1); 1.00 Pd;
–
–
Biso
–
0.7(3)
Pd21 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.66045(5), 0.25105(5), 0.16717(3); 1.00 Pd
0.0094(2), 0.0100(2), 0.0110(2), 0.0027(2),
0.0007(2), ꢀ0.0006(2)
0.655(2), 0.253(2), 0.160(1); 1.00 Pd;
–
–
Biso
–
0.8(3)
Pd22 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.81994(5), 0.37102(5), 0.08933(5); 1.00 Pd
0.0101(2), 0.0114(2), 0.0095(2), 0.0001(2),
0.0026(2), ꢀ0.0006(2)
0.822(1), 0.357(2), 0.089(1); 1.00 Pd;
–
–

ARTICLE IN PRESS
O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
1025
Table 5 (continued )
Biso
–
0.6(3)
Pd25 in 2a (0,0,0); occ.
U11, U22, U33, U23, U13, U12
0.254(3) Pd
0.26(1) Pd;
0.0094(2), 0.0100(2), 0.0110(2), 0.0027(2),
–
0.0007(2), ꢀ0.0006(2)
–
Biso
–
0.7(4)
Pd10 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.21812(5), 0.0821(1), 0.02624(5); 0.948(2) Pd
0.220(1), 0.079(1), 0.0247(9); 0.95(1) Pd;
0.0148(2), 0.0118(2), 0.0149(2), ꢀ0.0020(1),
–
0.0022(2), 0.0014(2)
–
Biso
–
0.9(4)
Pd10a in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.2466(9), 0.0924(9), 0.0053(7); 0.051(1) Pd
0.239(10), 0.100(9), 0.007(8); 0.05(1) Pd;
0.0148(2), 0.0118(2), 0.0149(2), ꢀ0.0020(1),
–
0.0022(2), 0.0014(2)
–
Biso
–
0.9(4)
Pd23 in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.60634(5), 0.0730(1), 0.00904(4); 0.947(3) Pd
0.607(1), 0.095(2), 0.003(1); 0.95(1) Pd;
0.0109(3), 0.0122(4), 0.0124(3), 0.0004(2),
–
0.0037(2), 0.0003(2)
–
Biso
–
0.8(4)
Pd23a in 4e (x, y, z); occ.
U11, U22, U33, U23, U13, U12
0.638(1), 0.137(1), 0.0196(7); 0.053(3) Pd
0.635(8), 0.168(10), 0.017(6); 0.05(1) Pd;
0.012(5), 0.016(7), 0.010(4), 0.005(4),
–
0.008(4), 0.005(4)
–
Biso
–
0.9(3)
B1 in 4e (x, y, z); occ.
Uisoc, (Bis,d)
0.0082(7), 0.4329(8), 0.0974(5); 1.00 B
0.067(9), 0.425(10), 0.101(6); 1.00 B;
0.011(1)
0.5
B2 in 4e (x, y, z); occ.
0.1166(7), 0.1872(8), 0.2220(5); 1.00 B
0.145(10), 0.200(9), 0.224(7); 1.00 B;
Uiso (Biso
B3 in 4e (x, y, z); occ.
Uiso (Biso
B4 in 4e (x, y, z); occ.
Uiso (Biso
B5 in 4e (x, y, z); occ.,
Uiso (Biso
B6 in 4e (x, y, z); occ.
Uiso (Biso
B7 in 4e (x, y, z); occ.
Uiso (Biso
B8 in 4e (x, y, z); occ.d
Uiso (Biso
)
0.012(1)
0.5
0.3123(7), 0.6155(8), 0.2272(5); 1.00 B
0.292(10), 0.622(11), 0.208(7); 1.00 B;
)
0.012(1)
0.5
0.3434(9), 0.3884(9), 0.4524(6); 1.00 B
0.366(8), 0.405(10), 0.455(6); 1.00 B;
)
0.020(2)
0.5
0.3847(7), 0.2998(8), 0.2760(5); 1.00 B
0.403(9), 0.313(9), 0.303(6); 1.00 B;
)
0.013(1)
0.5
0.4942(7), 0.0533(8), 0.3951(5); 1.00 B
0.498(9), 0.016(9), 0.412(8); 1.00 B;
)
0.013(1)
0.5
0.8115(7), 0.3734(8), 0.2192(5); 1.00 B
0.803(10), 0.394(11), 0.216(4); 1.00 B;
)
0.010(1)
0.5
0.6832(9), 0.2526(9), 0.0215(7); 0.947(3)
0.020(1)
0.683(8), 0.234(9), 0.013(6); 0.95 B;
)
0.5
–
Residual density; max; min in (electrons/nm3) ꢁ 1000
4.401; –3.095
a
Crystal structure data are standardized using the program Structure Tidy [42].
2
2
2
Ã
b
Anisotropic atomic displacement parameters Uij in [102 nm2]. The anisotropic temperature factor is defined as exp½ꢀ2p2ðU11h2a þU22k2b þU33l2c
þ
Ã
Ã
2U23klbÃcÃþ2U12hkaÃbÃþ2U13hlaÃcÃÞꢂ.
c
Isotropic atomic displacement parameters Uiso (Biso) in [102 nm2]. Uiso (Biso) values were obtained via isotropic refinement procedure.
d
Fixed parameter.
Fig. 5. X-ray diffraction pattern of Ce3Pd25ꢀxB8ꢀy. The solid line derives from the Rietveld refinement. Yobs.ꢀYcalc. is the intensity difference between experimental data
and Rietveld calculations.

Table 6
Crystallographic data of selected Ce–Pd–B alloys annealed at 850 1C.
No.
Nominal composition Ce–Pd–B (at%)
X-ray phase analysis
Space group
Structure type
Lattice parameters in nm
a
b
c
1
2
37.5–62.5
32–36–32
Ce3Pd5
Ce3Pd4
Unknown
Pu3Pd4
1.3722(2)
0.5812(1)
R3
CeB4
P4/mbm
UB4
0.72043(6)
0.40962(5)
Ce3Pd5
CeB4
Unknown
UB4
–
–
4
5
28–28–44
27–70–3
P4/mbm
Pm3m
0.72036(1)
–
0.40905(1)
–
Ce3Pd5
CePd3Bx
Unknown
CaTiO3
–
0.4181(2)
Ce3Pd5
unknown
CaTiO3
–
6
26–42–32
CePd3Bx
0.41810(5)
–
Pm3m
CeB4
P4/mbm
UB4
0.72066(6)
–
0.40973(5)
–
Ce3Pd5
CePd3Bx
Unknown
CaTiO3
9
24.3–72.7–3.0
23.8ꢀ76.2
23.5–70.6–5.9
22.2–66.6–11.1
22–55–23
0.41694(4)
Pm3m
Pm3m
Pm3m
Pm3m
10
11
12
13
CePd3
AuCu3
CaTiO3
CaTiO3
CaTiO3
0.41231(1)
0.41954(5)
0.41954(3)
0.420(2)
CePd3Bx
CePd3Bx
CePd3Bx
Pm3m
CeB4 (traces)
CePd3Bx
P4/mbm
UB4
0.72053(8)
0.4196(1)
0.40952(8)
–
15
21.5–64.5–14.0
CaTiO3
Pm3m
Pm3m
Pm3m
CeB6 (traces)
CePd3 cubic
CaB6
–
17
19
20–80
AuCu3
0.41131(9)
0.40623(8)
0.41951(5)
20–60–20
CePd3Bx
CaTiO3
Pm3m
C2/c
Ce3Pd25ꢀxB8ꢀy (traces)
CeB6 (traces)
La3Pd25ꢀxB8ꢀy
CaB6
–
–
Pm3m
20
23
24
25
19–74–7
CePd3Bx
CaTiO3
0.4164(1)
1.7822(3)
Pm3m
C2/c
Ce3Pd25ꢀxB8ꢀy (traces)
La3Pd25ꢀxB8ꢀy
1.0389(1)
1.1678(1)
1.5989(1)
1.5955(2)
b
¼101.50(1)1
18–72–10
CePd3Bx
CaTiO3
0.41838(5)
1.1722(1)
Pm3m
P21/c
Ce3Pd25ꢀxB8ꢀy
La3Pd25ꢀxB8ꢀy
1.04535(9)
¼101.90(1)1
b
18–70–12
CePd3Bx
CaTiO3
0.41786(8)
1.1737(1)
Pm3m
P21/c
Ce3Pd25ꢀxB8ꢀy
La3Pd25ꢀxB8ꢀy
1.04439(8)
¼101.96(1)1
b
16.7–16.7–66.7
CePd3Bx
CeB6
CaTiO3
CaB6
0.41856(3)
0.41410(1)
Pm3m
Pm3m
CeB4
P4/mbm
UB4
–
0.7209(2)
0.40629(8)
0.4059(2)
0.40843(4)b
0.41961(5)
0.4094(2)
1.6003(5)
26
27
16–80–4
16–78–6
cubic
cubic
cubic
CePd3Bx
–
–
–
28
15–50–35
CaTiO3
Pm3m
P21/c
Ce3Pd25ꢀxB8ꢀy
–
La3Pd25ꢀxB8ꢀy
–
1.1734(3)
1.0543(1)
¼102.08(2)1
b
Pm3m
CeB6 (traces)
CePd3Bx
CaB6
–
30
32
14.3–71.4–14.3
13–77–10
CaTiO3
0.41782(3)
Pm3m
P21/c
Ce3Pd25ꢀxB8ꢀy
La3Pd25ꢀxB8ꢀy
1.17571(6)
1.04398(3)
¼102.07(1)1
1.59688(9)
1.16195(4)
b
Cubic
–
–
0.40842(3)a,b
1.78112(7)
CePd8B2ꢀx
C2/c
CePd8B2ꢀx
1.03634(3)
¼118.54(1)1
b

33
36
12–79–9
cubic
–
–
0.40567(9)
–
CePd8B2ꢀx (traces)
Ce6Pd47ꢀxB6
C2/c
C2/m
CePd8B2ꢀx
La6Pd47ꢀxB6
11–79.5–10.5
1.03591(1)
1.80779(3)
¼108.32(1)1
1.01986(1)
b
cubic
0.40799(1)
0.40307(1)
1.7790(3)
cubic
37
11–78–11
CePd8B2ꢀx
C2/c
CePd8B2ꢀx
1.0349(1)
¼118.75(1)1
1.80882(8)
¼108.33(1)1
1.1708(2)
–
b
Ce6Pd47ꢀxB6
C2/m
La6Pd47ꢀxB6
1.03647(5)
1.02065(5)
b
cubic (traces)
cubic
0.4085(1)
0.40483(1)a
40
41
10–80–10
10–79–11
–
–
CePd8B2ꢀx (traces)
Ce6Pd47ꢀxB6 (traces)
Ce6Pd47ꢀxB6
C2/c
C2/m
C2/m
CePd8B2ꢀx
La6Pd47ꢀxB6
La6Pd47ꢀxB6
1.0375(1)
1.7829(4)
1.8058(2)
¼108.38(1)1
1.0379(1)
¼118.50(1)1
1.0216(1)
1.1641(2)
b
CePd8B2ꢀx (traces)
C2/c
CePd8B2ꢀx
b
cubic (traces)
Ce3Pd25ꢀxB8ꢀy
0.40343(4)
1.1747(1)
42
45
9.5–66.7–23.8
9.5–76.5–14
P21/c
C2/c
La3Pd25ꢀxB8ꢀy
CePd8B2ꢀx
1.0567(1)
¼102.18(2)1
1.03601(4)
¼118.55(1)1
1.6045(1)
b
CePd8B2ꢀx
1.7803(1)
0.40471(9)a
1.7859(2)
1.77691(2)
1.17332(4)
1.16152(6)
b
cubic
Ce6Pd47ꢀxB6 traces
CePd8B2ꢀx
C2/m
C2/c
La6Pd47ꢀxB6
CePd8B2ꢀx
46
47
48
49
9.2–75.0–15.8
9.2–74.2–16.6
9.2–73.1–17.7
9.2–80–10.8
1.0447(1)
¼118.54(1)1
1.03904(1)
¼118.47(1)1
1.04300(2)
¼102.12(1)
1.1733(1)
1.16875(2)
1.59590(7)
b
CePd8B2ꢀx
C2/c
CePd8B2ꢀx
b
Ce3Pd25ꢀxB8ꢀy
P21/c
Ce3Pd25ꢀxB8ꢀy
b
cubic
0.40397(3)a
1.78136(9)
CePd8B2ꢀx
C2/c
CePd8B2ꢀx
1.03657(3)
¼118.58(1)1
1.16492(5)
1.5970(1)
b
Pd3B (traces)
Pnma
Fe3C
51
52
9.0–70.1–20.9
9–45–46
Ce3Pd25ꢀxB8ꢀy
P21/c
La3Pd25ꢀxB8ꢀy
1.1678(1)
1.04688(5)
¼102.06(1)1
b
CeB6
CaB6
0.41418(2)
1.2672(9)
Pm3m
C2/c
Pd5B2
Mn5C2
0.4951(2)
¼96.9(1)1
1.0542(1)
0.5481(4)
1.6023(3)
b
Ce3Pd25ꢀxB8ꢀy
P21/c
La3Pd25ꢀxB8ꢀy
1.1745(2)
b
¼102.11(1)1
53
55
56
58
6.9–72.4–20.7
6–76–18
Pd3B
Pnma
Fe3C
0.5458(2)
1.1734(4)
0.7563(3)
0.4847(2)
1.5966(5)
Ce3Pd25ꢀxB8ꢀy
P21/c
La3Pd25ꢀxB8ꢀy
1.0455(2)
b
¼102.13(1)1
Pd3B
Pnma
Fe3C
0.54619(5)
1.7799(2)
0.75700(7)
0.48471(5)
1.1672(3)
CePd8B2ꢀx
C2/c
CePd8B2ꢀx
1.03883(7)
b
¼118.47(1)1
6–71–23
Pd3B
Pnma
Fe3C
0.5455(1)
1.1630(3)
0.7558(2)
0.4841(1)
1.5861(4)
Ce3Pd25ꢀxB8ꢀy
P21/c
La3Pd25ꢀxB8ꢀy
1.0313(2)
b
¼101.79(1)1
5–80–15
cubic
0.40341(3)a
1.7807(1)
CePd8B2ꢀx (traces)
C2/c
CePd8B2ꢀx
Fe3C
1.03827(4)
1.16764(6)
0.4828(1)
b
¼118.52(1)1
Pd3B
Pnma
0.54654(1)
0.7566(1)
a
Lattice constants evaluated according to a cubic subcell.
Lattice parameters determined from stress-annealed sample.
b

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Fig. 6. System Ce–Pd–B; partial isothermal section at 850 1C up to 45 at% Ce. Some tie-lines are shown for the two-phase fields. Compositions and codes of the alloys
prepared are shown as open circles (see also Table 8).
Fig. 8. Compositional dependence of lattice parameters for the phases CePd8B2ꢀx
and Ce3Pd25ꢀxB3ꢀy from alloys quenched from 850 1C. Black symbols correspond
to single crystal data. For better comparison, the Ce3Pd25ꢀxB3ꢀy lattice (space
group P21/c) is used in the unit cell setting of the structure with space group C2/c.
Fig. 7. CePd8B2ꢀx, Ce3Pd25ꢀxB3ꢀy and Ce2Pd14+xB5ꢀy structures vs. B concentra-
tion as a function of temperature.
Geometrical relationships between two unit cell metrics and axial transformations
are shown in the inset.
relations for the structures CePd8B2ꢀx
Ce3Pd25ꢀxB8ꢀy are presented in Fig. 10 in Ba¨rnighausen
formalism [44]: the symmetry reduction is realized via
, La3Pd25ꢀxB8ꢀy and
a
splitting of certain atomic positions which violate the C2/c space
group symmetry (Table 7).
klassengleiche symmetry reduction k2 accompanied by shifts of
origin (0, 1/2, 1/2) and (1/2, 1/2, 0) for both La3Pd25ꢀxB8ꢀy- and
All three structures are quite complex and, to facilitate the
structural analysis, the approach of decomposition into charac-
teristic structural units is helpful. In the present case, the most
efficient technique was to express the structures in terms of
simpler components located at certain planes. For simplification,
only the Pd- and B-centered polyhedra are emphasized. In the
crystal structures La3Pd25ꢀxB8ꢀy and CePd8B2ꢀx, as seen along
the long crystallographic axis (Fig. 11), infinite slabs centered at
Ce3Pd25ꢀxB8ꢀy-structures, respectively, and
transformation of the unit cell. Fig. 2 (Supplementary Data)
presents the geometrical relations in direction between
a
(c, b, ꢀaꢀc)
c
CePd8B2ꢀx, Ce3Pd25ꢀxB8ꢀy and La3Pd25ꢀxB8ꢀy. It can be seen
that the presented structures differ essentially not only by
significant shifts of atoms caused by increase of degree of
freedom in the position of the atomic sites, but also by the

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1029
zE1/4, 3/4 and xE1/4, 3/4, respectively, and composed of only
boron-centered polyhedra alternate with slabs at zE0, 1/2 (and
xE0, 1/2, respectively) containing also icosahedra centered by
boron are inter-linked in an irregular way in both structures
(Fig. 11). The lower boron content in CePd8B2ꢀx as compared to
the La3Pd25ꢀxB8ꢀy-structure can be visualized when the
structures are viewed along the a- and c-direction, respectively:
the slabs with boron-centered polyhedra in La3Pd25ꢀxB8ꢀy at
xE1/2 are replaced in CePd8B2ꢀx by slabs containing also
polyhedra centered by palladium (compare Fig. 12b and d).
In the structure of La6Pd47ꢀxB6, the slabs at yE1/4 and 3/4
(view along b, Fig. 11) contain the chains of palladium centered
polyhedra (Pd14 in 4f (1/4, 1/4, 1/2), which are stretched parallel
to the a-axis, and zig–zag chains of boron-centered triangular
prisms running in the same direction. At yE0 and 1/2, the slabs
are composed of a stacking of palladium-centered cubes (Pd16 in
2c (0, 0, 1/2) and icosahedra (Pd15 in 2d (0, 1/2, 1/2), Pd17 in 2a
(0, 0, 0)), and tetragonal antiprisms of boron. If viewed along c, the
structure shows (slabs at zE1/2) infinite sheets of palladium-
centered icosahedra and cubes joined at common corners
(Fig. 12). At zE0, the trigonal prisms and tetragonal antiprisms
centered by boron are inter-connected and form ovals, which
surround the palladium centered icosahedra (Pd17).
palladium. In CePd8B2ꢀx
(Pd13 in 4a (0,0,0)) within the slabs at xE0, 1/2 are connected
at corners and form chains along the c-axis. In La3Pd25ꢀxB8ꢀy
, the palladium-centered icosahedra
,
the palladium-centered icosahedra (Pd25 in 2a (0,0,0) within the
slabs at zE0, 1/2) do not interconnect but are linked in b
direction by B-centered edge-connected triangular prisms. Within
the slabs with boron centered polyhedra, the coordination units of
3.4. The system Yb–Pd–B
3.4.1. Phase equilibria in the Yb–Pd–B system at 850 1C
Results obtained from the phase analysis of the samples are
listed in Table 8 and the corresponding partial isothermal section
at 850 1C is shown in Fig. 13. Judging from unit cell constant
variations of YbPd3Bx, the limit of
B solubility in YbPd3
Fig. 9. Lattice parameter for CePd3Bx vs. boron content.
corresponds to the value reported recently in the literature [15].
Fig. 10. Group–subgroup scheme for CePd8B2ꢀx, Ce3Pd25ꢀxB8ꢀy and La3Pd25ꢀxB8ꢀy structures. (a) Stays for partly occupied atomic position, empty squares correspond to
unoccupied atomic sites.

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Table 7
Structural parameters for the CePd8B2ꢀx, Ce3Pd25ꢀxB8ꢀy [17] and La3Pd25ꢀyB8ꢀy [17].
CePd8B2ꢀx (x¼0.46) in C2/c
Ce3Pd25ꢀxB8ꢀy (x¼1.25, y¼2.00) in P21/c
La3Pd25ꢀyB8ꢀy (x¼1.75, y¼0.07) in P21/c
Ce1 in 8f (x, y, z)
Ce1 (4e) 0.13011, 0.56995, 0.34940
Ce3 (4e) 0.62792, 0.41846, 0.33996
Ce2 (4e) 0.24889, 0.37295, 0.00027
Pd3 (4e) 0.05574, 0.23852, 0.08312
Pd18 (4e) 0.44672, 0.25726, 0.41328
Pd2 (4e) 0.04532, 0.30660, 0.40981
Pd16 (4e) 0.44466, 0.18241, 0.08311
Pd6 (4e) 0.12618, 0.50487, 0.67016
Pd15 (4e) 0.37758, 0.49367, 0.33002
Pd7 (4e) 0.15969, 0.72332, 0.18952
Pd12 (4e) 0.27867, 0.20492, 0.17735
Pd4 (4e) 0.06089, 0.08460, 0.32240
Pd17 (4e) 0.43687, 0.40812, 0.17425
Pd11 (4e) 0.22249, 0.29117, 0.32778
Pd21 (4e)0.65775, 0.26336, 0.18023
Pd1 (4e) 0.00085, 0.33575, 0.22983
Pd19 (4e) 0.50008, 0.15603, 0.26656
Pd9 (4e) 0.19173, 0.45523, 0.17910
Pd13 (4e) 0.30976, 0.03844, 0.32335
Pd14 (4e) 0.31968, 0.63043, 0.08927
Pd22 (4e) 0.81828, 0.36598, 0.08715
Pd5 (4e) 0.06414, 0.59214, 0.04177
Pd20 (4e) 0.56123, 0.40224, 0.03899
Pd8 (4e) 0.16304, 0.82687, 0.03174
Pd25 (2a) 0,0,0; Occ. 0.50
La1 (4e) 0.13374, 0.56675, 0.34969
La3 (4e) 0.63178, 0.41148, 0.33042
La2 (4e) 0.24480, 0.37282, 0.00077
Pd3 (4e) 0.05183, 0.23589, 0.08490
Pd18 (4e) 0.45221, 0.25328, 0.40847
Pd2 (4e) 0.03801, 0.31167, 0.41038; Occ. 0.916
Pd16 (4e) 0.43730, 0.17115, 0.07630
Pd6 (4e) 0.12355, 0.50450, 0.67239
Pd15 (4e) 0.38022, 0.48256, 0.32652
Pd7 (4e) 0.16254, 0.72379, 0.19057
Pd12 (4e) 0.27557, 0.20246, 0.18001
Pd4 (4e) 0.05714, 0.08773, 0.32382
Pd17 (4e) 0.439428, 0.39686, 0.16881
Pd11 (4e) 0.22250, 0.28869, 0.33131
Pd21 (4e) 0.66042, 0.25038, 0.16713
Pd1 (4e) 0.00199, 0.33761, 0.23095
Pd19 (4e) 0.50137, 0.14704, 0.26224
Pd9 (4e) 0.19143, 0.45483, 0.17853
Pd13 (4e) 0.30879, 0.03434, 0.32564
Pd14 (4e) 0.32107, 0.62460, 0.09332
Pd22 (4e) 0.82049, 0.37011, 0.08916
Pd5 (4e) 0.06264, 0.59388, 0.04148
Pd20 (4e) 0.56116, 0.40029, 0.03436
Pd8 (4e) 0.17168, 0.82557, 0.02820
Pd25 (2a) 0,0,0; Occ. 0.712
–
Ce2 in 4e (0, y, 1/4)
Pd1 in 8f (x, y, z)
–
Pd2 in 8f (x, y, z)
–
Pd3 in 8f (x, y, z)
–
Pd4 in 8f (x, y, z)
–
Pd5 in 8f (x, y, z)
–
Pd6 in 8f (x, y, z)
–
Pd7 in 8f (x, y, z)
–
Pd8 in 8f (x, y, z)
–
Pd9 in 8f (x, y, z)
–
Pd10 in 8f (x, y, z)
–
Pd11 in 8f (x, y, z)
Pd13 in 4a (0,0,0)
–
Pd28 (2b) 1/2,0,0; Occ. 0.50
–
Pd12 in 4e (0, y, 1/4)
–
–
–
Pd10 (4e) 0.2255, 0.0826, 0.0166, Occ. 0.80
Pd27 (4e) 0.2700, 0.4187, 0.4868; Occ. 0.20
Pd26 (4e) 0.6543, 0.1594, 0.0283; Occ. 0.70
Pd23 (4e) 0.6055, 0.0746, 0.0116; Occ. 0.30
B1 (4e) 0.0024, 0.4296, 0.1002
B6 (4e) 0.4936, 0.0598, 0.3993
B3 (4e) 0.3130, 0.6147, 0.2208
B7 (4e) 0.8125, 0.3740, 0.2183
B2 (4e) 0.1249, 0.1858, 0.2222
B5 (4e) 0.3761, 0.3059, 0.2824
–
Pd10 (4e) 0.21592, 0.08348, 0.02277; Occ. 0.931
–
–
–
Pd24 (4e) 0.6381, 0.1306, 0.0192; Occ. 0.077
Pd23 (4e) 0.60608, 0.07331, 0.01000; Occ. 0.923
B1 (4e) 0.0088, 0.4315, 0.0987
B6 (4e) 0.4938, 0.0525, 0.3947
B3 (4e) 0.3122, 0.6134, 0.2276
B7 (4e) 0.8117, 0.3737, 0.2184
B2 (4e) 0.1172, 0.1833, 0.2207
B5 (4e) 0.3820, 0.3001, 0.2750
B4 (4e) 0.3395, 0.3877, 0.4522
B8 (4e) 0.6855, 0.2518, 0.0204; Occ. 0.923
–
B3 in 8f (x, y, z)
B1 in 8f (x, y, z)
B2 in 8f (x, y, z);Occ. 0.31(2)
–
–
–
–
The phase
t
1-Yb2Pd13.6B5 was found to form in single-phase
containing borides with heavy rare earths (R¼Tm, Lu) prefer the
Sc4Ni29B10-type yielding Ni5 atom in a partly filled 4b special
position and with boron in 8e [45]. In the Y2Pd14B5 structure [47],
the 4b atomic site is occupied by boron atoms whereas the 8e site
remains unoccupied, thus leading to a shrinking of the unit cell in
z direction as compared to other R2Pd14B5 compounds (Fig. 15).
Although full profile Rietveld analyses cannot differentiate
between slight differences in the occupancies of B and Pd
atoms, the small residual values for Yb2Pd13.6B5 and Lu2Pd13.2B5
based on the Y2Pd14B5 structure inferred the isotypism of these
compounds (Table 2).
conditions only in annealed alloys, whereas the X-ray powder
diffraction pattern of as-cast samples yielded the spectra of
YbPd3Bx, Pd5B2 and YbB6 indicating incongruent formation.
Lattice parameters of the cubic phase from YbPd3Bx–Pd3B
equilibrium field fit well for the interval of values observed for
YbPd3–YbPd3Bx solubility range. Similarly to the Ce–Pd–B system,
the X-ray powder diffraction data of stress-annealed samples
containing higher contents of palladium beyond the YbPd3–Pd3B
tie-line yielded spectra which contained weak superstructure
reflections but the base structure could be indexed according to a
cubic unit cell with a¼0.405 nm and cannot be regarded as
belonging to any of the known binary boundary phases.
3.5. Bonding and structural relationships
3.4.2. Crystal structure of
t
1-Yb2Pd13.6B5 and isotypic Lu2Pd13.2B5
For all four structures, La6Pd47ꢀxB6, CePd8B2ꢀx, La3Pd25ꢀxB8ꢀy
and Yb2Pd14ꢀxB5, the nonstoichiometric nature arises from two
types of disorder: (i) split of Pd sites, and (ii) partial occupancy of
atom sites. Among them, the structures CePd8B2ꢀx and
Yb2Pd14ꢀxB5 appear to be most ordered exhibiting only defects
on one boron and one palladium site, respectively. The two
remaining structures, La3Pd25ꢀxB8ꢀy and La6Pd47ꢀxB6, show in
addition to partial occupancy of certain atom sites, the split of
atomic positions of palladium. As it was shown above, the
interatomic distances for completely occupied rare earth and
palladium sites in all structures generally agree well with the sum
of metal atom radii. Inspection of the atom environment of Pd11
and Pd13 in CePd8B2ꢀx revealed that the elevated ADP of
Due to the lack of good quality single crystals, Rietveld
refinements were employed for the crystal structure investigation
of t1-Yb2Pd13.6B5. The X-ray powder pattern of this compound
suggested isotypism with the tetragonal structure of Sc4Ni29B10
[45]. Recently three new Sc4Ni29B10-derivative structural arrange-
ments have been reported, Nd2Pd14+xB5ꢀy [16], ErNi7B3 [46] and
Y2Pd14B5 [47]. For this structural family, the boron atoms are
found in structural units typical for rare earth intermetallic
borides, namely trigonal prisms and tetragonal antiprisms
(Fig. 14). Whilst the light rare earths, Gd and Th were found to
favor the Nd2Pd14+xB5ꢀy type of atomic arrangement with atomic
position 8e partly occupied by palladium or boron atoms, Ni

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1031
Fig. 11. Presentation of structures La3Pd25ꢀxB8ꢀy, CePd8B2ꢀx and La6Pd47ꢀxB6 projected along the long crystallographic axis. Two-dimensionally infinite slabs are arranged
in following order from left to right: for La3Pd25ꢀxB8ꢀy zE0, 1/4, 1/2, 3/4; for CePd8B2ꢀx xE0, 1/4, 1/2, 3/4; for La6Pd47ꢀxB6 yE1/4, 1/2, 3/4, 1.
Pd12 within a distorted tri-capped hexagonal antiprism is a
possible source of shortened bonds for the surrounding atoms
on one rectangular side by one additional La2 atom. The
antiprismatic coordination for boron is not so frequent in the
structures of d-metal-rich ternary borides. Fragments formed by
six Archimedean prisms linked via an empty cube were observed
(dPd13–Pd11¼0.25588 nm
and
dPd13–Pd2¼0.26088 nm).
The
shortening of Pd–B bonding is more evident: dB2–Pd4¼0.198 nm
and dB1–Pd3¼0.205 nm in CePd8B2ꢀx; dB2–Pd11¼0.2021 nm and
dB2–Pd8¼0.2084 nm in La6Pd47ꢀxB6; dB5–Pd12¼0.2042 nm and
dB3–Pd7¼0.2086 in La3Pd25ꢀxB8ꢀy; however, this phenomenon
appears to be a recurring feature also for binary borides with
the Fe3C-type structure being close in composition to our
structures investigated: dB–Fe¼0.1981 nm for Fe3B, dB–Co¼0.1957
in the structure of t-phases (Cr23C6-type) [43]. Another example
is the structure of Nd2Pd14+xB5ꢀy where distorted squared
antiprisms are inter-connected through a rectangular face [16].
Similarly, in the structure of La6Pd47ꢀxB6, the Archimedean
antiprisms are also inter-connected via rectangular faces where
the opposite rectangular faces are shared each with a polyhedron
centered by La (see Fig. 16c).
nm for Co B and dB–Ni¼0.1966 nm for Ni3B. Besides Fe3C type
3
borides, the decrease of minimal distances was observed for
certain borides rich in d-metal: Ho2Ni15B6 (dB–Ni¼0.1891 nm)
[48], CeNi12B6 (dB–Ni¼0.198 nm) [49], RNi4B (R¼Gd, Tb, Er;
dB–Ni¼0.2045 nm, 0.2046 nm and 0.2043 nm) [50] and Ce2Co5B2
(dB–co¼0.196 nm) [51].
B1 is surrounded by seven atoms of palladium: six atoms form
the triangular prism and one additional atom is located against
the rectangular face of the trigonal prism. Two mono-capped
triangular prisms of B1 share a common edge. Three La atoms are
bonded to B1: two La are linked with boron via two rectangular
faces of the triangular prism and the additional La atom is bonded
through the triangular face formed by an additional Pd-atom
(Fig. 16aꢀb). Lanthanum atoms, involved in these blocks, inter-
connect via common faces and corners. If the structure is viewed
along a, those slabs repeat at xE1/4 and 3/4. Similar fragments
were observed in Nd2Fe14B (Fig. 16d) where three rare earth
atoms are bound to one boron atom through the rectangular faces
of boron centered triangular prisms, and neodymium-centered
polyhedra are inter-connected via common faces and corners.
However the slabs formed in Nd2Fe14B are relatively flat as
compared to La6Pd47ꢀxB6, because the neodymium and boron
atoms reside in the same planes (Nd in 4g (x, y, 0); Nd in 4f (x, x, 0);
B in 4f (x, x, 0), whereas the atomic coordinate x for La and B in
La6Pd47ꢀxB6 are different (La 1 in 8j (x ,y, z) x¼0.28483(3),
Although the structure types of La6Pd47ꢀxB6, CePd8B2ꢀx
,
La3Pd25ꢀxB8ꢀy and Nd2Pd14+xB5ꢀy are unique, relations to other
structures can be easily recognized. Trigonal prisms connected by
their vertical edges occur in d-metal rich borides, such as in the
structure of CeCo3B2 and in the related structures of Nd2Fe14
B
[52], Ce2Ir5B2 [53], Ce2Co5B2 [51], Ca3Ni7B2 [54]. They differ from
the title compounds by the way of stacking into larger structural
fragments. In the structure of CeCo3B2, six boron atoms are
bonded to each cerium atom and the columns made of
boron centered triangular prisms are stretched laterally along
c-direction. In Ce2Ir5B2, Ce2Co5B2 and Ca3Ni7B2, the fragments of
CeCo3B2 are interleaved by structural fragments of Laves phases.
In La6Pd47ꢀxB6, there are two distinct atomic positions of
boron. B2 atoms are found in the Archimedean antiprisms capped

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Fig. 12. Comparison of structures La3Pd25ꢀxB8ꢀy, CePd8B2ꢀx and La6Pd47ꢀxB6 projected along [100], [001] and [001]. Slabs in La3Pd25ꢀxB8ꢀy at x¼0, 1 (a), xE1/2 (b); for
CePd8B2ꢀx at z¼0, 1 (c), zE1/2 (d); for La6Pd47ꢀxB6 zE0, 1 (e), zE1/2 (f).
y¼0.35008(2), z¼0.26059(4); La2 in 4i (x,0,z) x¼0.21660(5),
z¼0.29506(5); B1 in 8j (x,y,z) x¼0.3588(7), y¼0.1796(4),
z¼0.1056(7)).
As shown in Fig. 16e–k, the fragments observed in La6Pd47ꢀxB6
(e.g., edge sharing triangular prisms centered by boron atoms;
squared antiprism as a coordination unit of boron; blocks of boron

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1033
Table 8
Crystallographic data of Yb–Pd–B alloys annealed at 850 1C.
No.
Nominal composition Yb–Pd–B (at%)
X-ray phase analysis
Space group
Structure type
Lattice parameters in nm
a
b
c
2
3
33.3–66.6
30–62–8
YbPd2
YbPd3Bx
CaTiO3
0.40713(4)
Pm3m
Pm3m
YbPd2 (traces)
CePd3
6
7
25–75
AuCu3
CaTiO3
0.40499(1)
0.4083(1)
24–50–26
YbPd3Bx
Pm3m
YbB2
P6/mmm
P4/mbm
AlB2
0.32480(1)
0.70574(3)
0.40990(5)
0.37303(1)
0.39902(2)
YbB4
UB4
10
11
22–62–16
20.8–79.2
YbPd3Bx
CaTiO3
Pm3m
YbB4 (traces)
YbPd3
P4/mbm
UB4
AuCu3
0.40372(6)
0.39510(8)
0.40860(4)
0.41345(6)
Pm3m
Fm3m
Pm3m
Pd1ꢀxYbx
YbPd3Bx
YbB6
Pd
12
20–60–20
CaTiO3
CaB6
Pm3m
Yb2Pd14ꢀxB5 (traces)
YbPd3Bx
I41/amd
Y2Pd14B5-related
CaTiO3
14
15
20–50–30
0.40857(2)
0.4127(1)
0.40760(4)
Pm3m
Pm3m
YbB6
CaB6
16.6–72.2–11.1
YbPd3Bx
CaTiO3
Pm3m
Pd3B
Pnma
Fe3C
0.54610(3)
0.40686(3)
0.75612(4)
0.48491(4)
17
18
15–76–9
YbPd3Bx
CaTiO3
Pm3m
Pm3m
14–18–68
YbB6
CaB6
0.41478(1)
YbPd3Bx (traces)
CaTiO3
Pm3m
Yb2Pd14ꢀxB5
Cubic
I41/amd
Y2Pd14B5-related
0.83826(3)
0.40512(2)
0.4036(5)
1.6609(1)
19
21
11–79–10
YbPd3
AuCu3
Pm3m
9.5–66.7–23.8
Yb2Pd14ꢀxB5
YbPd3Bx
I41/amd
Y2Pd14B5-related
CaTiO3
0.83813(2)
0.40867(4)
1.66034(5)
Pm3m
C2/c
Pd5B2
Mn5C2
1.2802(1)
0.49739(4)
¼97.08(1)1
0.54094(7)
1.6624(1)
b
22
23
24
9.1–27.3–63.6
6.9–72.4–20.7
6–38–54
Yb2Pd14ꢀxB5
YbB6
I41/amd
Y2Pd14B5
CaB6
0.83788(2)
0.41472(3)
Pm3m
C2/c
Pd5B2
Mn5C2
1.2805(1)
0.49718(3)
¼97.16(1)1
0.54226(6)
b
YbPd3Bx
CaTiO3
0.40803(6)
Pm3m
C2/c
Pd5B2
Pd3B
Mn5C2
Fe3C
1.2774(1)
0.5459(1)
0.49482(1)
0.54674(3)
0.4853(1)
Pnma
b
¼97.07(1)1
0.7573(1)
YbB6
CaB6
0.41476(3)
0.46949(2)
Pm3m
Pd2B
Pnnm
CaCl2
UB12
0.51238(2)
0.31071(1)
YbB12 (traces)
Fm3m
25
26
6–75–19
4–78–18
YbPd3Bx
CaTiO3
Fe3C
0.4069(1)
Pm3m
Pd3B
Cubic
Pd3B
Pnma
0.5462(1)
0.40574(3)
0.54764(1)
0.7561(2)
0.4852(1)
Pnma
Fe3C
0.75593(1)
0.48578(1)
atom bonded to three rare earth atoms; face and corner connected
polyhedra of rare earth atoms) are also present in the structures of
CePd8B2ꢀx and La3Pd25ꢀxB8ꢀy. Although these three structures can be
The heat capacity data, CP(T), down to 2 K of Yb2Pd14B5 and
Lu2Pd14B5 are presented in Fig. 17a. The lack of distinct anomalies
in CP(T) for Lu2Pd14B5 indicates the absence of structural
transitions in the entire temperature range studied. Within the
low temperature limit (To5 K) the heat capacity can be
considered as a packing of structural fragments typical for Nd2Fe14
B
and Nd2Pd14+xB5ꢀy, the mutual dispositions of blocks are different.
In the following section, physical properties will be evaluated,
particularly those of Yb2Pd13.6B5 as a detailed description of the
physical behavior of the Ce–Pd–borides will be the subject of an
independent forthcoming article. Furthermore, we will use as a
short notation Yb2Pd14B5 instead of Yb2Pd13.6B5.
accounted for in terms of CP¼
gT+b
T3, yielding a Sommerfeld
value
g
¼17 mJ molꢀ1 Kꢀ2 and
b
¼0.0019 Jmolꢀ1 Kꢀ4, revealing a
Debye temperature yLDT ¼ 282 K as typical for metal-rich borides.
In order to explore the vibrational properties of the lattice also
at higher temperatures, the electronic contribution to the specific
heat was subtracted and a model consisting of a combination of
Debye and Einstein functions was adopted. Thermal expansion of
the crystallographic unit cell, especially at high temperatures, was
not taken in to account. Considering ꢃ21 atoms per formula unit,
the phonon dispersion relation of Yb2Pd14B5 consists of three
acoustic and 60 optical branches. The former constitutes the
Debye contribution, while the latter form the Einstein part. A fit
results in a Debye temperature yD¼88 K and three Einstein
3.6. Physical properties of t1-Yb2Pd13.6B5
To reveal the principal physics of Yb2Pd14B5 the temperature
dependent specific heat, temperature dependent electrical resis-
tivity and magnetic measurements were performed. Lu2Pd14B5
was taken as a non-magnetic analog.

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Fig. 13. System Yb–Pd–B; partial isothermal section at 850 1C up to 33 at% Yb. Alloys prepared are shown as empty circles (see also Table 8).
Fig. 15. Variations of the lattice parameters vs. rare earths in M2Pd14B5 closed and
open squares correspond to the lattice parameters of Th- and Y-compounds,
respectively.
received are characterized by an upturn at low temperature and a
maximum around 75 K. While the former is supposed to be a
signature of a low temperature magnetic instability (below the
experimental limit), the latter is attributed to crystalline electric
field (CEF) effects. A Schottky curve adjusted to the experimental
data reveals a doublet at 130 K and a quasi-quartet at 290 K above
the ground state doublet. Integrating Cmag/T over T, the resulting
magnetic entropy is presented in Fig. 17b. The limit of 2R ln 8 was
not reached at the highest temperature measured.
Fig. 14. Crystal structure of Yb2Pd14+xB5ꢀy in three dimensional view along [100]
axis and coordination polyhedra of Pd5(B2) atoms in related structures.
temperatures: TE1¼116 K, TE2¼207 K and TE3¼455 K with
weights of c1¼11, c2¼29 and c3¼20, respectively. To compare
the Debye temperature derived from the fit with the one
derived at low temperatures, the former has to be multiplied by
n1/3¼2.76, arriving at ycDorr ¼ 243 K.
The temperature dependent electrical resistivity of Yb2Pd14B5
is shown in Fig. 18 together with the resistivity of Lu2Pd14B5.
Obviously, the latter shows metallic behavior in the entire
Analyzing the magnetic contribution to the specific heat of
Yb2Pd14B5, Cmag can be revealed as a difference of heat capacities
of Yb2Pd14B5 and Lu2Pd14B5, i.e., Cmag¼CP(Yb)–CP(Lu). The data
temperature range; however, the negative curvature of
r(T)

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1035
Fig. 16. Structural relationships in La6Pd47ꢀxB6, CePd8B2ꢀx, La3Pd25ꢀxB8ꢀy and Yb2Pd14ꢀxB5. Arrangement of lanthanum and B1 coordination polyhedra in La6Pd47ꢀxB6:
projections along [100], slabs at xE1/4 (a), xE3/4 (b). Aggregation of La2 and B2 polyhedra in La6Pd47ꢀxB6 (c). Structure of Nd2Fe14B (d). Arrangement of coordination
polyhedra in the structure of CePd8B2ꢀx: Ce1B1 (e), Ce2B3 (f), Ce1Ce2B2 (g). Projection of La3Pd25ꢀxB8ꢀy along [010]: slabs at yE0 (h), yE1/2 (i). Linkage of La1La2B1
atoms in the structure of La3Pd25ꢀxB8ꢀy (j). Arrangement of B polyhedra in the structure of La3Pd25ꢀxB8ꢀy (k).
Fig. 17. (a) Temperature dependent specific heat Cp of Yb2Pd14B5 and Lu2Pd14B5 plotted as Cp vs. T (left axis). (b) Magnetic contribution of the specific heat Cmag(T) of
Yb2Pd14B5 plotted as Cmag vs. T. The dashed line represents the magnetic entropy Smag(T) and refers to the right axis.
does not evidence a simple behavior. Besides this, Lu2Pd14B5
exhibits rather large overall resistivity values as derived from a
this s–d scattering process is responsible for a characteristic T3
term at elevated temperatures ðT 4yDÞ. From this model a Debye
temperature of 230 K is obtained and the Mott–Jones pre-factor
residual resistivity r0¼210
tendency to saturation as a consequence of the strong curvature
of (T). The temperature dependence of the resistivity was
mO cm. Moreover the system shows a
amounts to roughly 1 ꢁ 10ꢀ6
mO
cm Kꢀ3. On the other hand, the
r
parallel resistance model, generally used for materials with large
absolute resistivities, does not fit properly.
In general, physics of Yb compounds is governed from a
balance of the Kondo effect, the RKKY interaction and CEF effects.
Distinct hints to the Kondo effect in Yb2Pd14B5 are obvious from
described by the Bloch–Gru¨neisen formula modified by the
model of Mott and Jones [55], accounting for scattering of
conduction electrons on rather localized d-electrons. On the
assumption of spherical s- and d-bands as well as Debye phonons

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O. Sologub et al. / Journal of Solid State Chemistry 183 (2010) 1013–1037
The magnetic configuration of Yb2Pd14B5 can be proven by
susceptibility measurements (T), for which the data of a 3 T run
w
are shown in Fig. 19. A phase transition, in agreement with
specific heat and electrical resistivity is not present above 2 K. To
quantitatively account for temperatures above 20 K,
a fit
according to the modified Curie–Weiss law was employed,
yielding
a temperature independent Pauli-like susceptibility
w0ffi1 10ꢀ3 emu/mol, an effective moment meff¼4.2 mB and the
*
Curie temperature yp¼ ꢀ3 K. The effective moment is close to the
theoretical value associated with the Yb3+ state, i.e., 4.54 mB
,
favoring the 4f13 electronic configuration as ground state of the Yb
ions. The small negative paramagnetic Curie temperature hints at
antiferromagnetic correlations, in line with
antiferromagnetic ground state.
a
possible
4. Conclusions
Phase relations in the Ce–Pd–B and Yb–Pd–B systems at 850 1C
were determined from X-ray powder diffraction of alloys
annealed at 850 1C in the concentration ranges up to 45 and
33 at% of Ce and Yb, respectively. Two extended homogeneity
fields, CePd8B2ꢀx–Ce3Pd25ꢀxB3ꢀy and CePd3Bx were found to exist
in equilibrium. CePd3 was established to incorporate up to 13 at%
of B from X-ray powder diffraction; the unit cell parameters of
CePd3Bx reach their maximum at x¼0.25. The crystal structure of
CePd8B2ꢀx (x¼0.46 and 0.32) (own structure type, C2/c space
group) was studied by single crystal X-ray diffraction. The
continuous transition from CePd8B2ꢀx to La3Pd25ꢀxB8ꢀy-type
structure within the homogeneity field on progressing from
the boron-poor to boron-rich members was revealed from
Rietveld refinement of X-ray powder diffraction data. One more
new ternary phase was found in the palladium rich region;
however, due to the lack of good quality single crystal, the
Fig. 18. Temperature dependent electrical resistivity
r
of Yb2Pd14B5 and
(273). The inset shows
low temperature resistivity data for Yb2Pd14B5 at magnetic fields up to 12 T.
Lu2Pd14B5 plotted in a normalized representation
r(T)/r
structure of the new compound (
t1-Ce6Pd47ꢀxB6 (C2/m space
group, a¼1.03594(2) nm, b¼1.80782(3) nm, c¼1.01997(2) nm,
b
¼108.321(1)1) was determined from Rietveld refinement of
X-ray powder diffraction data applying the structural model
obtained from La6Pd47ꢀxB6 (x¼0.19) single crystal (new structure
type, C2/m space group, a¼1.03988(2) nm, b¼1.81941(5) nm,
c¼1.02418(2) nm,
b¼108.168(1)1). Ce6Pd47ꢀxB6, CePd8B2ꢀx and
La3Pd25ꢀxB8ꢀy structures exhibit the fragments common with
Nd2Fe14B and Nd2Pd14+xB5ꢀy
The ternary compound
1-Yb2Pd14ꢀxB5 (x¼0.4) (I41/amd space
.
t
group) was detected to be in equilibrium with YbPd3Bx, YbB6,
Pd5B2 and Pd3B in the Yb–Pd–B system. The isotypic compound
structurally related to Y2Pd14B5 was observed with Lu. In the
course of this study, the attempts to determine the structures of
unknown compounds in the binary Yb–Pd system were under-
taken; however, a good quality single crystal was obtained only
for the Yb5Pd2 compound. In agreement with the literature data,
the compound forms with a Mn5C2-type. The refined atomic
coordinates slightly deviate from those reported in the literature
from photograph method but the atomic position of Pd atom was
Fig. 19. Temperature dependent magnetic susceptibility
1/ vs. T. Data are taken at 3 T. The solid line corresponds to a least squares fit to
the experimental data in terms of a modified Curie–Weiss law.
w of Yb2Pd14B5, plotted as
w
the temperature dependent resistivity
characteristics found at zero field are a negative logarithmic slope
of (T) below about 12 K and a maximum at 2 K. While the former
r(T). The most important
r
refers to Kondo interactions in the CEF ground state, the latter can
be considered as a signature of coherence originated from the
periodic arrangement of the Yb ions in Yb2Pd14B5. The decrease of
the resistivity below 2 K might result from the onset of long-range
magnetic order, in agreement with the heat capacity data. The
application of external magnetic fields causes an initial decrease
found to be occupied for 96.9% leading to a composition Yb5Pd1.94
.
Physical properties derived for Yb2Pd13.6B5 are characterised
by an almost 3+ state of the Yb ion, leading to long range
magnetic order below 2 K. The Kondo- and CEF effects control the
paramagnetic temperature domain.
of the electrical resistivity as well as
a shift of the low
temperature maximum to higher temperatures until it becomes
totally suppressed at 8 T (see inset Fig. 18). These observations are
typical features of Kondo lattices where the quenching of Kondo
interaction by external magnetic field depletes the scattering
Acknowledgments
Research supported by Austrian National Science Foundation
FWF projects 18054 and M1067-N20.
intensity and thus reduces r(T).

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