Crystal structure of EuLaCuS3

Article abstract of DOI:10.1134/S0036023612030254

The crystal structure of the EuLaCuS₃complex sulfide synthesized for the first time has been solved by X-ray powder diffraction. Crystals are orthorhombic, space group Pnma, Ba₂MnS₃-type structure, a = 8.1297(3) ?, b = 4.0625(1) ?, c = 15.9810(4) ?, V = 527.80(3) ?³, Z = 4, and ρ_calc = 5.669 g/cm ³. The La and Eu atoms are randomly disordered over two crystallographic positions with a coordination number of 7, and the Eu(La)-S bond lengths range from 2.892(6) to 3.078(6) ?. The CuS₄ tetrahedra with Cu-S interatomic distances of 2.358(5)-2.40(1) ? form chains running along the b axis.

Full text of DOI:10.1134/S0036023612030254

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2012, Vol. 57, No. 4, pp. 574–578. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.V. Ruseikina, L.A. Solov’ev, O.V. Andreev, 2012, published in Zhurnal Neorganicheskoi Khimii, 2012, Vol. 57, No. 4, pp. 638–642.
PHYSICAL METHODS
OF INVESTIGATION
Crystal Structure of EuLaCuS3
A. V. Ruseikinaa, L. A. Solov’evb, and O. V. Andreeva
a Tyumen State University, ul. Semakova 10, Tyumen, 625003 Russia
b Institute of Chemistry and Chemical Engineering, Siberian Branch, Russian Academy of Sciences,
ul. Karla Marksa 42, Krasnoyarsk, 660049 Russia
Received January 20, 2011
Abstract—The crystal structure of the EuLaCuS3complex sulfide synthesized for the first time has been
solved by Xꢀray powder diffraction. Crystals are orthorhombic, space group Pnma
a
,
Ba2MnS3ꢀtype structure,
= 4, and ρcalc = 5.669 g/cm3. The La
and Eu atoms are randomly disordered over two crystallographic positions with a coordination number of 7,
and the Eu(La)–S bond lengths range from 2.892(6) to 3.078(6) Å. The CuS4 tetrahedra with Cu–S interꢀ
= 8.1297(3) Å, b = 4.0625(1) Å, c = 15.9810(4) Å, V , Z
= 527.80(3) Å3
atomic distances of 2.358(5)–2.40(1) Å form chains running along the b axis.
DOI: 10.1134/S0036023612030254
Some powder Xꢀray diffraction data on the crystalꢀ the initial sulfides mixed in the ratio 2EuS : 1La2S3 :
chemical characteristics of the SrLaCuS3 complex
sulfide are available from [1]: orthorhombic crystal
Cu2S in a graphite crucible placed into a sealed evacuꢀ
ated doubleꢀwalled quartz ampoule. The ampoule was
heated in an electrical furnace up to 1570 K and
allowed to stay for 30 min. Cooling was conducted in
the switchꢀoff furnace. The samples were annealed in
sealed evacuated quartz ampoules at 970 K for 3000 h.
system, space group Рnmа, a = 11.157(2) Å, b =
4.1003(6) and = 11.545(2) Å. In a singleꢀcrystal
Å
,
c
Xꢀray diffraction experiment, the crystal structure of
PbLaCuS3 was solved by Brennan and Ibers [2]. Crysꢀ
tals are orthorhombic, space group Pnma
8.091(3) = 4.093(1) and = 15.996(5) Å. The
ratio of the ionic radii of sevenꢀcoordinated ions
Sr2+: Pb2+: Eu2+ = 1.21 : 1.23 : 1.2 Å [3]) allows us
, a =
Å,
b
Å
,
c
The identity of the synthesized compound was
confirmed by microstructural analysis (a METAM PB
microscope) and Xꢀray powder diffraction (PANalytiꢀ
cal X’Pert PRO diffractometer equipped with a PIXcel
detector, CoКα radiation, graphite monochromator,
298 K). A powdery sample was prepared by pounding
with addition of octane in an agate mortar. The Xꢀray
diffraction pattern was taken within the diffraction
(
r
r
r
to predict the formation of EuLaCuS3. No informaꢀ
tion on the EuLaСuS3 crystal structure has been
found. The presence of dꢀ and f elements in the crystal
lattice gives rise to practically valuable properties.
Brennan and Ibers [2] noted that PbLaCuS3 is a diaꢀ
magnetic and a semiconductor with a bandgap energy
of 1.5 eV. In EuLnCuS3 compounds (Ln = Eu–Lu) [4] angle range of 10° ≤ 2θ ≤ 125°. The EuLaCuS3 unit
containing nonmagnetic Ln ions, the ferromagnetic
alignment of Eu2+ momentums occurs at 3.4–4.4 K.
The ferromagnetic transition in EuLnCuS3 comꢀ
pounds containing magnetic Ln ions occurs at 5.0 K.
The present paper presents the solution of crystal
structure EuLаCuS3 based on powder Xꢀray diffracꢀ
tion data.
cell parameters were determined with the ITO softꢀ
ware [6]. In addition to the main phase, La3S4, EuS,
and CuLaS2 impurities were found in the sample. The
crystal structure was refined by the derivative differꢀ
ence minimization (DDM) method [7] using Xꢀray
powder diffraction data with consideration for the
effects of preferred orientation, the anisotropic broadꢀ
ening of peaks, and the surface roughness (RꢀDDM =
8.67%, RBragg = 4.39%). The data for isostructural
PbLaCuS3 [2] was used as the initial model. The
experimental, calculated, and difference Xꢀray difꢀ
fraction patterns of the studied sample are compared
in Fig. 1. Atomic coordinates and isotropic thermal
parameters are listed in Table 1. The shortest selected
cation–anion distances (Table 2) were calculated on
the basis of the structural data. The selected bond
angles are given in Table 3. The crystal structures were
EXPERIMENTAL
Cu2S was synthesized from elementary copper (11ꢀ4
high purity grade) and sulfur (15ꢀ3 high purity grade)
in sealed evacuated doubleꢀwalled quartz ampoules.
EuS and La2S3 were synthesized from oxides of EvOꢀZh
and LaOꢀD grades in a Н2S and СS2 flow at 1300 K [5].
According to Xꢀray powder diffraction, the simple sulꢀ
fides were single phases. Within the error of chemical
analysis, the sulfides had the stoichiometric composiꢀ
tions. EuLаCuS3 samples were prepared by alloying visualized with the use of the Diamond 3 software [8].
574

CRYSTAL STRUCTURE
575
I1/2
10
20
30
40
50
60
70
80
90 100 110 120
, deg
2θ
Fig. 1. Experimental (solid line), calculated (dashed line), and difference (points) Xꢀray diffraction patterns of an EuLaCuS
3
sample after the refinement of its structure by the DDM method (
RꢀDDM = 8.67%). The peak positions for the major phase are
indicated with strokes.
RESULTS AND DISCUSSION
dinated by four sulfur ions with the formation of a disꢀ
torted tetrahedron. A CuS4 tetrahedron is formed of
the 2 × S(1) + S(2) + S(3) atoms, and the average Cu–
S distance is 2.369 Å (Table 2).
The Xꢀray diffraction pattern of the studied comꢀ
pound was indexed in terms of orthorhombic crystal
system, space group Pnma
,
a
Å
= 8.1297(3)
= 527.80(3) Å3
Å,
,
In the EuLaCuS3 structure, CuS4 tetrahedra share
the S(1) vertices to form continuous chains running in
b
= 4.0625(1)
Å,
c
= 15.9810(4)
,
V
Z
= 4, and ρcalc = 5.669 g/cm3. The crystal has a layꢀ
eredꢀblock structure (Fig. 2). The copper ion is coorꢀ the direction [010]. The chains are spaced by rareꢀ
Table 1. Atomic coordinates and thermal parameters and site occupancy factors in the EuLaCuS3
Atom
x
y
z
Occupancy
Uiso,
Å2
Eu(1)
Eu(2)
La(1)
La(2)
Cu
0.2536(3)
0.0908(3)
0.2536(3)
0.0908(3)
0.1180(6)
0.014(1)
0.181(1)
0.381(1)
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.0383(1)
0.7851(1)
0.0383(1)
0.7851(1)
0.3661(3)
0.6002(5)
0.2194(6)
0.4291(5)
0.55(5)
0.012(1)
0.013(1)
0.012(1)
0.013(1)
0.025(2)
0.017(3)
0.011(2)
0.012(2)
0.45(5)
0.45(5)
0.55(5)
1
1
1
1
S(1)
S(2)
S(3)
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 4 2012

576
RUSEIKINA et al.
d) in the EuLaCuS3 structure
Table 2. Interatomic distances (
Bond
d,
Å
Bond
d,
Å
Bond
d, Å
Eu(1)–S(1)
Eu(1)–S(1)
Eu(1)–S(2)
Eu(1)–S(3)
Eu(1)–S(3)
<Eu(1)–S>
2
2
×
×
2.948(7)
3.059(9)
2.954(9)
2.892(6)
3.076(9)
2.967
Eu(2)–S(1)
Eu(2)–S(2)
Eu(2)–S(2)
Eu(2)–S(3)
<Eu(2)–S>
3.022(9)
2.942(6)
3.005(6)
3.078(6)
3.010
Cu–S(1)
Cu–S(2)
Cu–S(3)
<Cu–S>
2
×
2.358(5)
2.400(9)
2.361(9)
2.369
2×
2×
2×
Average values are boldfaced.
Table 3. Selected bond angles (ω) in the EuLaCuS3 structure
Angle
ω
, deg
Angle
ω
, deg
Angle
ω, deg
S(1)Eu(1)S(1)
S(1)Eu(1)S(1)
S(1)Eu(1)S(2)
S(1)Eu(1)S(3)
S(1)Eu(1)S(3)
S(2)Eu(1)S(1)
S(2)Eu(1)S(3)
S(3)Eu(1)S(1)
S(3)Eu(1)S(1)
S(3)Eu(1)S(1)
S(3)Eu(1)S(2)
S(3)Eu(1)S(3)
S(3)Eu(1)S(3)
87.2(2)
78.4(2)
78.4(2)
143.5(2)
125.1(2)
147.8(2)
68.7(2)
87.8(2)
158.4(2)
80.0(2)
121.0(2)
89.2(2)
74.3(2)
S(1)Eu(2)S(3)
S(2)Eu(2)S(1)
S(2)Eu(2)S(1)
S(2)Eu(2)S(2)
S(2)Eu(2)S(2)
S(2)Eu(2)S(2)
S(2)Eu(2)S(2)
S(2)Eu(2)S(3)
S(2)Eu(2)S(3)
S(2)Eu(2)S(3)
S(2)Eu(2)S(3)
S(3)Eu(2)S(3)
S(1)Eu(2)S(3)
138.3(2)
77.4(2)
79.9(2)
157.2(2)
87.2(2)
89.3(2)
85.2(2)
76.4(2)
121.3(2)
132.4(2)
68.1(2)
82.6(2)
138.3(2)
S(1)CuS(1)
S(1)CuS(3)
S(1)CuS(2)
S(3)CuS(2)
118.8(3)
108.3(3)
108.7(3)
102.9(3)
earth metal atoms that coordinate sulfur atoms. A of 2.967 Å. The theoretical value calculated from the
characteristic feature of the EuLaCuS3 structure is ionic radii of La3+ and Eu2+ (for CN = 7) with considꢀ
that Eu and La atoms are disordered over two positions eration for the site occupancy (Eu : La = 0.55 : 0.45) is
in a manner similar to that in isostructural PbLaCuS3 2.995 Å [3]. The Eu(2)S7 prism is formed of the S(1) +
[2] and SrLaCuSe3 [9].
2S(2) + 2S(3) atoms with an average Eu(2)–S disꢀ
tance of 3.010 Å (theoretical value with consideration
of site occupancies is 2.985 Å).
Both rareꢀearth ions in the structure EuLaCuS3
coordinate seven sulfur ions to form two coordination
polyhedra (monocapped trigonal prisms Eu(1)S7 and
The Eu(1)S7 prisms are linked to one another by
Eu(2)S7) with coordination numbers of 6 + 1 (Fig. 3). common
The Eu(1)S7 prism is formed of the 2S(1) + S(1) + and with common S(3)S(1) edges along the
2
× S(1) and
2
× S(3) edges along the
а axis
b
axis to
S(2) + 2S(3) atoms with an average Eu(1)–S distance form twoꢀdimensional networks in the аb plane. The
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 4 2012

CRYSTAL STRUCTURE
577
а
с
S(3)
S(2)
S(2)
S(2)
S(2)
S(1)
Cu
S(3)
S(3)
S(1)
M
1
S(3)
S(1)
S(3)
Fig. 2. Geometrical projection [010] of the EuLaCuS structure. The Cu, Eu(La), and S atoms are denoted by smallꢀ, mediumꢀ, and
3
largeꢀdiameter circles, respectively.
semiꢀbold lines.
М
is Eu(1)La(1) and
M
is La(2)Eu(2). The Cu–S interatomic distances are denoted by
1
2
(а)
(b)
S(2)
S(3)
S(1)
3.005
S(3)
S(2)
S(2)
S(3)
S(1)
S(1)
Fig. 3. Coordination geometry of (a) Eu(1)La(1) atoms and (b) La(2)Eu(2) atoms in EuLaCuS . The interatomic distances in
3
singleꢀcup trigonal prisms are given in Å.
Eu(2)S7 prisms are linked by
2
× S(2) edges along the dating copper ions. As noted in [2], an analogous
axis, and arrangement is typical of ꢀLa2S3 and some other
а
axis and by S(2)S(2)S(3) faces along the
b
α
also form twoꢀdimensional networks in the аb plane. compounds with a similar composition. Thus, the
The Eu(1)S7 and Eu(2)S7 prisms are linked by the EuLaCuS3 structure may be considered as a result of
S(2)S(1) and S(2)S(3) edges along the c axis to form a the replacement of some La atoms in αꢀLa2S3 for Eu
threeꢀdimensional structure with channels accommoꢀ atoms and the incorporation of Cu atoms into approxꢀ
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 4 2012

578
RUSEIKINA et al.
2. T. D. Brennan and J. A. Ibers, J. Solid State Chem. 97
,
imately tetrahedral positions between the LaS7 prisms,
this providing an explanation, in particular, for the disꢀ
torted structure of CuS4 tetrahedra and the random
distribution of Eu2+ and La3+ ions, which have close
sizes, over two crystallographic positions.
377 (1992).
3. R. D. Shannon, Acta Crystallogr., Sect. A 32
,
751 (1976).
4. M. Wakeshima, F. Furuuchi, and Y. Hinatsu, J. Phys.:
Condens. Matter 16, 5503 (2004).
ACKNOWLEDGMENTS
5. V. G. Bamburov and O. V. Andreev, Russ. J. Inorg.
Chem. 47, 598 (2002).
This work was supported by the Federal Target Proꢀ
gram “Scientific and Pedagogical Resources for Innoꢀ
vative Russia” for 2009–2013 and State Contract
nos. 6K/143ꢀ09 (P 646) and NKꢀ409/5 (P 2263).
6. J. W. Visser, J. Appl. Crystallogr. 2, 89 (1969).
7. L. A. Solovyov, J. Appl. Crystallogr. 37, 743 (2004).
8. K. Brandenburg, DIAMOND—Visual Crystal Structure
Information System CRYSTAL IMPACT (Postfac
1251, Dꢀ53002 Boon).
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