Structural phase transition of ScSb and YSb with a NaCl-type structure at high pressures

Article abstract of DOI:10.1016/S0038-1098(02)00889-X

By use of synchrotron radiation, powder X-ray diffraction of ScSb and YSb with a NaCl-type structure has been studied up to 45GPa at room temperature. A first-order phase transition from the NaCl-type (B1) to a CsCl-type structure (B2) began to occur at around 28GPa for ScSb and at around 26GPa for YSb. Crystal data of the high-pressure phase of both antimonides are obtained. The high-pressure structural behavior of ScSb and YSb is similar to that of heavier LnSb (Ln=Dy-Lu). The B1-B2 transition for ScSb and YSb can be understood according to the rigid sphere model. The bulk moduli of ScSb and YSb are about 58GPa at ambient pressure.

Full text of DOI:10.1016/S0038-1098(02)00889-X

Solid State Communications 125 (2003) 543–546
www.elsevier.com/locate/ssc
Structural phase transition of ScSb and YSb with a NaCl-type
structure at high pressures
a
J. Hayashi , I. Shirotani , K. Hirano , N. Ishimatsu , O. Shimomura , T. Kikegawa
a,
a
b
b
c
*
aFaculty of Engineering, Muroran Institute of Technology, 27-1, Mizumoto-cho, Muroran-shi 050-8585, Japan
bSPring-8, 1-1-1, Kouto, Mikazuki-cho, Sayo-gun, Hyougo 679-5198, Japan
cIMSS, KEK, 1-1, Oho, Tsukuba-shi, Ibaraki 305-0801, Japan
Received 18 October 2002; accepted 4 December 2002 by H. Akai
Abstract
By use of synchrotron radiation, powder X-ray diffraction of ScSb and YSb with a NaCl-type structure has been studied up to
45 GPa at room temperature. A first-order phase transition from the NaCl-type (B1) to a CsCl-type structure (B2) began to
occur at around 28 GPa for ScSb and at around 26 GPa for YSb. Crystal data of the high-pressure phase of both antimonides are
obtained. The high-pressure structural behavior of ScSb and YSb is similar to that of heavier LnSb (Ln ¼ Dy–Lu). The B1–B2
transition for ScSb and YSb can be understood according to the rigid sphere model. The bulk moduli of ScSb and YSb are about
58 GPa at ambient pressure.
q 2003 Elsevier Science Ltd. All rights reserved.
PACS: 61.10.Nz; 61.66.Fn
Keywords: B. Chemical synthesis; C. Crystal structure and symmetry; D. Phase transitions; E. Strain, high pressure; E. Synchrotron radiation
1. Introduction
Nd) have a tetragonal structure (distorted CsCl-type) at high
pressures. The high-pressure form of the middle LnSb
(Ln ¼ Sm, Gd and Tb) is unknown. The heavier LnSb
(Ln ¼ Dy, Ho, Er, Tm and Lu) show the B1–B2 transition
at high pressures though the same transition is not observed
in the heavier LnP and LnAs [5,6]. The transition pressures
of LnSb do not depend on the structure of their high-
pressure phases, but increase with decreasing lattice
constant in the NaCl-type structure [3]. A lattice constant
of YSb with the NaCl-type structure almost agrees with that
of DySb. It is expected that the pressure-induced phase
transition of YSb is similar to that of heavier LnSb. The
lattice constant of ScSb with the NaCl-type structure is
much smaller than that of LuSb. Thus, the high-pressure
structural behavior in ScSb is very interest.
The high-pressure structural behavior of binary AB
compounds with a NaCl-type structure has been a popular
topic in condensed matter research. The majority of these
compounds undergo the first-order structural phase tran-
sition from the NaCl-type (B1) to the CsCl-type (B2)
structure at high pressures. Lanthanide monoantimonides
LnSb (Ln ¼ lanthanide) have the NaCl-type structure at
ambient pressure. By use of synchrotron radiation, powder
X-ray diffraction of LnSb with the NaCl-type structure has
systematically been studied up to 45 GPa at room
temperature. First-order phase transitions with the crystal-
lographic change occur for LnSb at high pressures [1–4].
The structure of high-pressure phases of LnSb is classified
into three groups [3]. The lighter LnSb (Ln ¼ La, Ce, Pr and
By use of synchrotron radiation, we have studied powder
X-ray diffraction of ScSb and YSb with the NaCl-type
structure up to 45 GPa at room temperature and found the
B1–B2 transition at high pressures. In this paper the high-
pressure structural behavior of ScSb and YSb is discussed.
*
Corresponding author. Tel.: þ81-143-46-5544; fax: þ81-143-
46-5501.
E-mail address: sirotani@eee.elec.muroran-it.ac.jp (I.
Shirotani).
0038-1098/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.
PII: S0038-1098(02)00889-X

544
J. Hayashi et al. / Solid State Communications 125 (2003) 543–546
2. Experimental
Table 1
X-ray diffraction data of the high-pressure form (single phase) of
ScSb
ScSb and YSb were prepared by reaction of stoichio-
metric amounts of each rare earth metal and antimony in a
sealed silica tube at around 800 8C. These compounds
prepared by us were characterized by powder X-ray
diffraction using Cu Ka radiation and silicon as a standard.
By use of synchrotron radiation, powder X-ray diffraction
patterns of ScSb and YSb were measured with a diamond-
anvil cell and an imaging plate up to 45 GPa at room
temperature [2–4]. Incident beam was monochromatized by
Si (111) crystals. The pressure in the diamond-cell was
determined from a pressure shift In the sharp R-line
fluorescence spectrum of ruby. A 4:1 methanol–ethanol
solution was used as the pressure-transmitting fluid.
ScSb at 43 GPa
h
k
l
d (obs.)
d (cal.)
I/I0 (obs.)
I/I0 (cal.)
1
1
1
2
2
2
2
0
1
1
0
1
1
2
0
0
1
0
0
1
0
3.576
2.361
1.950
1.704
1.474
1.377
1.186
3.357
2.374
1.938
1.679
1.501
1.371
1.187
40
100
22
8
25
100
8
19
13
40
13
5
14
20
curve for ScSb. The cell volume with the NaCl-type
structure monotonically decreases with increasing pressure
up to 28 GPa. The structural change to the CsCl-type
structure occurs with the volume collapse of about 1% at
around 34 GPa. When the pressure is removed, the
diffraction lines of the NaCl-type structure reappear at
around 10 GPa. The experimental data can be fitted by a
Birch equation of state [7]:
3. Results and discussion
Fig. 1 shows powder X-ray diffraction patterns of ScSb
at high pressures. The profile indicates only characteristic
lines of the NaCl-type structure at around 1.5 GPa. The d-
values of 111, 200, 220, 311, 222, 400, 331, 420, 422, 511,
440, 531, 600, 620 and 622 lines of ScSb decrease with
increasing pressure up to 25 GPa. New diffraction lines
appear at around 28 GPa and grow with increasing pressure.
The characteristic lines of the CsCl-type structure are
observed in the new high-pressure phase. A single phase of
the high-pressure form is obtained above 43 GPa. X-ray
diffraction data of this single phase of ScSb are given in
Table 1. All lines of the high-pressure phase are indexed in
25=3
P ¼ ð3=2ÞB0½ðV=V0Þ27=3 2 ðV=V0Þ
ꢀ ½ðV=V0Þ22=3 2 1Š}
Š{1 2 3=4ð4 2 B00Þ
ð1Þ
where B0 is the bulk modulus, B00 its first pressure derivative,
V the volume, and P is the pressure. A least-squares fit to the
data of ScSb gives the following values: B0 ¼ 58 ^ 3 GPa
and B00 ¼ 9.5 ^ 0.8.
Fig. 3 shows the Sc–Sc and Sc–Sb distances in ScSb at
high pressures. The Sc–Sb distance in the NaCl-type
the cubic CsCl-type structure. Crystal data of the single
3
˚
˚
phase of ScSb are a ¼ 3.36(1) A, V ¼ 37.9(5) A at 43 GPa.
˚
structure is 2.92 A at ambient pressure. This distance is
Fig. 2 shows the cell volume/formula unit vs pressure
much shorter than the sum of ionic radii of Sc3þ (0.81 A)
˚
and Sb32 (2.45 A). The Sc–Sb distance is slightly shorter
˚
˚
than the sum of the atomic radius of Sc (1.62 A) and the
˚
covalent radius of Sb (1.38 A), longer than the sum of
˚
˚
the covalent radii of Sc (1.44 A) and Sb (1.38 A). Thus, the
chemical bond between Sc and Sb atoms has the covalent
Fig. 1. Powder X-ray diffraction patterns of ScSb at high pressures:
(a) NaCl-type structure; (b) Coexistence of NaCl- and CsCl-type
structures; (c) CsCl-type structure.
Fig. 2. Cell volume/formula unit vs pressure curve for ScSb.

J. Hayashi et al. / Solid State Communications 125 (2003) 543–546
545
Table 2
X-ray diffraction data of the high-pressure form (single phase) of
YSb
Ysb at 37 GPa
h
k
l
d (obs.)
d (cal.)
I/I0 (obs.)
I/I0 (cal.)
1
1
1
2
2
2
0
1
1
1
1
2
0
0
1
0
1
0
3.777
2.483
2.062
1.560
1.452
1.248
3.532
2.498
2.039
1.580
1.442
1.249
6
100
22
6
3
100
1
1
9
43
14
8
3
˚
˚
a ¼ 3.53(1) A, V ¼ 44.0(5) A at 37 GPa. The cell volume
vs pressure curve for YSb can be fitted by a Birch equation
of state. A least-squares fit to the data of YSb gives the
following values: B0 ¼ 58 ^ 3 GPa and B00 ¼ 6.2 ^ 0.6.
Crystal data of the high-pressure form for ScSb, YSb and
heavier LnSb (Ln ¼ Dy, Ho, Er, Tm and Lu) are
summarized in Table 3. These compounds show the B1–
B2 transition at high pressures. It is well known that ionic
crystals like the alkali halide have the CsCl-type structure if
the ratio of their ionic radii (rc/ra) is above 0.732. As
mentioned above, ScSb is not the simple ionic crystal. The
Sc–Sb distances in the CsCl-type structure almost agree
with the sum of the atomic radius (RSc) of Sc and the
Fig. 3. Sc–Sc and Sc–Sb distances in ScSb at high pressures.
character. When the B1–B2 transition occurs at around
34 GPa, the Sc–Sb distance suddenly increases and
˚
becomes 2.94 A in the CsCl-type structure. This almost
˚
agrees with the Sc–Sb distance (2.92 A) in the NaCl-type
structure at ambient pressure. On the other hand, the Sc–Sc
distance in ScSb abruptly decreases if the B1–B2 transition
occurs.
Fig. 4 shows powder X-ray diffraction patterns of YSb at
high pressures. Characteristic lines of the NaCl-type
structure shift to the high degree region with increasing
pressure. New diffraction lines appear at around 26 GPa and
grow with increasing pressure. Low- and high-pressure
phases coexist between 26 and 36 GPa. The single phase of
the high-pressure form is obtained above 37 GPa. X-ray
diffraction data of this single phase of YSb are given in
Table 2. All lines are indexed in the cubic CsCl-type
structure. Crystal data of the single phase of YSb are
covalent radius (RSb) of Sb. The ratio of their radii (RSb/
RSc,Y) is 0.85 for ScSb and 0.77 for YSb. These values
suggest that ScSb and YSb have the 8 coordination (CsCl-
type structure) at high pressures. Thus, the structure of high-
pressure form of both compounds can be understood
according to the rigid sphere model. The high-pressure
structural behavior of ScSb and YSb is similar to that of
heavier LnSb, but does not resemble that of LaSb that
changes from the B1 to the tetragonal structure at high
pressure. This must arise from the large atomic radius of La
˚
(1.87 A).
Fig. 5 shows transition pressures vs lattice constants in
the NaCl-type structure for metal monoantimonides, MSb
(M ¼ Sc, Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm
and Lu). X-ray diffraction of LaSb and CeSb has already
been studied at high pressures [1]. We have again
Table 3
Crystal data of the high-pressure form (single phase) for the heavier
LnSb (Ln ¼ Dy, Ho, Er, Tm, Lu), YSb and ScSb
3
V (A )
˚
a (A)
˚
Compound
P (GPa)
Structure
ScSb
YSb
43
37
28
31
35
31
33
CsCl-type
CsCl-type
CsCl-type
CsCl-type
CsCl-type
CsCl-type
CsCl-type
3.36(1)
3.53(1)
3.54(1)
3.57(2)
3.50(3)
3.46(1)
3.46(2)
37.8(5)
44.0(5)
44.5(5)
45.5(6)
43.0(9)
41.6(5)
41.5(6)
DySb
HoSb
ErSb
TmSb
LuSb
Fig. 4. Powder X-ray diffraction patterns of YSb at high pressures:
(a) NaCl-type structure; (b) coexistence of NaCl- and CsCl-type
structures; (c) CsCl-type structure.

546
J. Hayashi et al. / Solid State Communications 125 (2003) 543–546
Fig. 6. Electrical resistivity of ScSb with the NaCl-type structure at
low temperatures.
Acknowledgements
Fig. 5. Transition pressures vs lattice constants curve in the NaCl-
type structure for metal monoantimonides, MSb (M ¼ Sc, Y, La,
Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu); the transition
pressure of LaSb has been studied by Leger et al. [1]. Black circle
shows the present work.
This work was partly supported by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Science
and Culture of Japan: No. 13874040(IS) and No.
14204032(IS).
investigated the pressure-induced phase transition of CeSb
with synchrotron radiation [8]. The transition pressure of
CeSb is 4 GPa higher than the results obtained by Leger et al.
The transition pressures of these compounds increase with
decreasing lattice constant in the NaCl-type structure. The
structure of the high-pressure phase of MSb is classified into
three groups. The lighter LnSb (Ln ¼ La, Ce, Pr and Nd)
have the tetragonal structure (distorted CsCl-type). The
high-pressure form of the middle LnSb (Ln ¼ Sm, Gd and
Tb) is unknown. On the other hand, the heavier LnSb
(Ln ¼ Dy, Ho, Er, Tm, and Lu), YSb and ScSb show the
typical B1–B2 transition at high pressures. As mentioned
above, the structure of high-pressure form of these
antimonides can be understood according to the rigid sphere
model. The high-pressure structural behavior in the heavier
LnSb (Ln ¼ Dy, Ho, Er and Tm) with many f electrons is
similar to that of LuSb, YSb and ScSb. Thus, the pressure-
induced phase transition in the heavier LnSb is insensitive to
the f electrons.
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[7] F. Birch, Phys. Rev. 71 (1947) 809.
Fig. 6 shows the electrical resistivity of ScSb with the
NaCl-type structure at low temperatures. The resistivity of
the compound decreases linearly to temperature from 280
down to 75 K. ScSb shows the metallic behavior below
room temperature. This result suggests that ScSb does not
[8] J. Hayashi, K. Yamanashi, K. Akita, I. Shirotani, N. Ishimatsu,
O. Shimomura, Spring-8 User Experiment Report, 6, 2000 B,
48.
behave as a simple ionic compound Sc3þSb32
.