Phase equilibria in the V-Ni-Sb system

Article abstract of DOI:10.1134/S0020168507060106

Phase relations in the V-Ni-Sb system have been studied by x-ray diffraction, and the 1070-K section of its phase diagram has been constructed in the region 0-67 at % Sb. The VSb phase (NiAs structure) is shown to have a homogeneity range: V_1.04-1.00Sb_0.96-1.00 (a = 0.4274(1)-0.4266(2) nm, c = 0.5464(2)-0.5448(4) nm). The binary antimonides with the NiAs structure dissolve the third component. V solubility in NiSb is within 3.5 at %. Ni dissolution in VSb is accompanied by partial Ni substitution for V and Ni incorporation into position 2d of space group P6₃/mmc, up to the composition V_0.84Ni_0.32Sb_0.84 (a = 0.42187(6) nm, c = 0.54000(9) nm).

Full text of DOI:10.1134/S0020168507060106

ISSN 0020-1685, Inorganic Materials, 2007, Vol. 43, No. 6, pp. 608–613. © Pleiades Publishing, Inc., 2007.
Original Russian Text © Ya.F. Lomnytska, O.P. Pavliv, 2007, published in Neorganicheskie Materialy, 2007, Vol. 43, No. 6, pp. 692–697.
Phase Equilibria in the V–Ni–Sb System
Ya. F. Lomnytska and O. P. Pavliv
Franko National University, ul. Kirila i Mefodiya 6, Lviv, 79005 Ukraine
e-mail: yalomnytska@yahoo.com
Received January 16, 2006; in final form, November 27, 2006
Abstract—Phase relations in the V–Ni–Sb system have been studied by x-ray diffraction, and the 1070-K sec-
tion of its phase diagram has been constructed in the region 0–67 at % Sb. The VSb phase (NiAs structure) is
shown to have a homogeneity range: V1.04–1.00Sb0.96–1.00 (a = 0.4274(1)–0.4266(2) nm, c = 0.5464(2)–
0.5448(4) nm). The binary antimonides with the NiAs structure dissolve the third component. V solubility in
NiSb is within 3.5 at %. Ni dissolution in VSb is accompanied by partial Ni substitution for V and Ni incorpo-
ration into position 2d of space group P63/mmc, up to the composition V0.84Ni0.32Sb0.84 (a = 0.42187(6) nm,
c = 0.54000(9) nm).
DOI: 10.1134/S0020168507060106
INTRODUCTION
radiation). Intensity data for structural analysis were
collected on the DRON-3M (CuKα radiation, step size
of 0.05°, counting time of 10 s per data point). All crys-
tallographic calculations were made using the CSD
software package [5].
Earlier phase-diagram studies of the V–Ni–Sb sys-
tem were concentrated on the formation of compounds.
The VNiSb compound (MgAgAs structure type, sp. gr.
F43m, a = 0.5785 nm [1]) was shown to form at 870 K.
Using high-pressure synthesis, Noda et al. [2] obtained
a compound which, most likely, had an Ni2In-type
structure. From the unit-cell volume of that compound,
its composition was inferred to be V0.6NiSb (sp. gr.
P63/mmc, a = 0.4217 nm, c = 0.5398 nm). The structure
of the VNi0.26Sb phase (sp. gr. P63/mmc, a =
0.42527(5) nm, c = 0.54443(6) nm) was determined by
single-crystal x-ray diffraction (XRD) and was shown
to be related to the Ni2In type [4]. In this paper, we
report a systematic study of the phase equilibria in the
V–Ni–Sb system and the 1070-K section of its phase
diagram.
RESULTS AND DISCUSSION
In the V–Ni system, we obtained all the binary com-
pounds reported earlier to exist at 1070 K: V3Ni (Cr3Si
structure type), σ-VNi (CrFe) with an appreciable
homogeneity range, VNi2 (MoPt2), and VNi3 (TiAl3).
Their lattice parameters are listed in Table 1.
In the Ni–Sb system at 1070 K, we obtained the ear-
lier reported compounds Ni5Sb2 (Ni5Sb2) and NiSb
(NiAs). According to our results, the homogeneity
range of the latter compound can be represented by
Ni1.09–1.00Sb0.91–1.00 (Fig. 1a) and is slightly narrower
than that in the phase diagram presented in [6].
EXPERIMENTAL
In theV–Sb system, we obtained the earlier reported
compounds V3Sb (Cr3Si), V3Sb2 (Fe3Sn2), V5Sb4
(Ti5Te4) (by sintering an elemental powder mixture at
1070 K three times), VSb (NiAs), and VSb2 (CuAl2).
Since no V–Sb phase diagram has been reported to
date, we studied this system in detail. In the composi-
tion range 42–56 at % Sb, samples were prepared at
2 at % Sb intervals by sintering at 1070 K in three steps.
Only VSb was found to have a homogeneity range.
From the composition dependences of its lattice param-
eters (Fig. 1b), the VSb phase was inferred to exist in
the composition range V1.04–1.00Sb0.96–1.00. The lattice
parameters of all the phases in the V–Sb system are
given in Table 1.
The V–Ni–Sb system was studied at 1070 K in the
composition region 0–67 at % Sb. Samples for this
investigation were prepared from high-purity (99.9+%)
metal powders. After pressing, the green compacts
were sintered at 1070 K for 200 h in evacuated silica
ampules. Next, the samples were ground and sintered at
the same temperature for an additional 800 h. At low Sb
concentrations, the sintered samples were arc-melted
and then homogenized by annealing at 1070 for 800 h,
followed by quenching in cold water without breaking
the vacuum. In our studies, we used only those samples
which differed in weight from the starting mixture by
no more than 2%.
The phase composition of the samples was deter-
mined by powder XRD with a DRON-3M diffractome-
ter (CuKα radiation) and Debye–Scherrer camera (CrK
The 1070-K section of the V–Ni–Sb phase diagram
(0–67 at % Sb), inferred from the present XRD results
for 80 samples, is displayed in Fig. 2.
608

PHASE EQUILIBRIA IN THE V–Ni–Sb SYSTEM
Table 1. Crystal data for phases of the V–Ni–Sb system
609
Structure
type
Phase
Sp. gr.
a, Å
b, Å
c, Å
Source
[7]
Sb
Ni
α-As
4.3084
11.247
R3 m
4.309(1)
3.5238
3.5231(8)
11.286(4) This work
Cu
[7]
This work
*
Ni0.90Sb0.10
3.592
[8]
*
Ni0.92Sb0.08
3.588
[8]
*
Ni0.92Sb0.08
Fm3m
Im3m
3.596(3)
3.539
This work
[8]
*
Ni0.92V0.08
*
Ni0.84V0.16
3.5465(4)
3.5557(3)
3.0240
This work
This work
[7]
Ni0.86V0.10Sb0.04
V
α-Fe
*
V
0.85Ni0.15
2.9900
[8]
*
V
0.93Ni0.07
3.0134(3)
12.9458
This work
Ni5Sb2
5.4271
11.4568
[8]
β = 151.71°
Ni5.0–4.4Sb2.0–2.6
Ni5Sb2 ë2
12.896(7)–12.9743(6) 5.425(5)–5.427(2)
11.4432(2)–
11.4300(6)
This work
β = 151.57(9)°–
151.61(1)°
Ni1.12–0.94Sb0.88–1.06
4.032–3.910
5.200–5.130
5.1750(2)–
5.1430(6)
This work
This work
Ni1.09–1.00 0.91–1.00
Sb
NiAs
P63/mmc 4.015(1)–3.9376(4)
This work
*
Ni1.00V0.07Sb0.93
3.9348(5)
3.9398(4)
5.131(2)
*
Ni0.93V0.07Sb1.00
5.1408(6) This work
7.220 [8]
7.222(4)–7.248(6) This work
3.549 [8]
2.529(1)–2.554(3) 7.971(8)–7.661(4) 3.555(3)–3.537(2) This work
VNi3
V1.0–1.4Ni3.0–2.6
VNi2
V1.0–1.1Ni2.0–1.9
3.540
3.537(1)–3.547(2)
TiAl3
MoPt2
I4/mmm
Immm
2.559
7.641
σ-VNi: (V1.2Ni0.8
)
8.955
9.004
4.625
4.663
[8]
[8]
(V1.3Ni0.7
)
CrFe
P42/mnm
Pm3n
V1.03–1.42Ni0.97–0.58
V3Ni
8.888(3)–9.059(4)
4.557(4)–4.699(3) This work
Cr3Si
Cr3Si
Fe3Sn2
4.710
4.706(2)
4.932
4.9416(2)
5.551
5.557(3)
9.81
9.802(2)
[8]
This work
[8]
This work
[8]
This work
[8]
V3Sb
Pm3n
V3Sb2
20.35
20.30(2)
3.50
R3 m
V5Sb4
Ti5Te4 I4/m
3.502(4) This work
5.440 [8]
5.464(2)–5.448(4) This work
5.464(2)–
5.4033(8)
5.442(4)–5.366(4) This work
VSb
NiAs
P63/mmc
4.285
V1.04–1.00Sb0.96–1.00
4.274(1)–4.266(2)
4.274(1)–4.2128(4)
V
1.04–0.90Ni0–0.14Sb0.96
This work
V1.0–0.88Ni0–0.12Sb1.00
V1.00–0.84Ni0–0.12Sb1.00–0.84
4.266(2)–4.244(2)
4.274(1)–4.2187(6)
5.464(2)–
5.4000(9)
This work
VSb2
V0.96Sb2
V1.00–0.96Sb2
CuAl2
I4/mcm
6.5541
5.6365
[8]
[9]
6.5528(2)
5.8071(3)
6.548(1)–6.558(2)6
5.638(1)–5.644(1) This work
[1]
VNiSb
MgAgAs
5.860(5)
F4 3m
V
0.6NiSb
Ni2In
Ni2In
P63/mmc
P63/mmc
4.217
4.2527
5.398
5.443
[3]
[4]
VNi0.26Sb
* Limit of the solid solution.
INORGANIC MATERIALS Vol. 43 No. 6 2007

610
LOMNYTSKA, PAVLIV
(a)
(b)
0.09
0.075
0.065
0.08
~
1
2
~
0.55
~
~
0.52
0.54
~
0.50
~
~
~
0.43
0.40
0.39
Ni1.0 – xSb1.0 + x
0.40
1.0 – xSb1.0 + 5x
–0.1
0
0.1
x
–1.0
0
0.1
x
V
Fig. 1. Composition dependences of lattice parameters for (a) NiSb and (b) VSb; (1) single- and (2) two-phase samples.
Sb
(a)
1
2
3
V3Sb2 (1070 K)
VSb
V2Sb4
NiSb
V3Sb2
Ni2Sb2
V3Sb
Ni
VNi5 VNi2
σ(VNi) V3Ni
V
(b)
at % Sb
50
48
46
44
42
40
NiSb
VSb
V2Sb4
V3Sb2
Fig. 2. 1070-K section of the V–Ni–Sb phase diagram in the region 0–67 at % Sb: (1) single-, (2) two-, and (3) three-phase samples.
INORGANIC MATERIALS Vol. 43 No. 6 2007

PHASE EQUILIBRIA IN THE V–Ni–Sb SYSTEM
611
Table 2. Crystal data for NiV0.07Sb0.93 and Ni0.93V0.07Sb1.00 (sp. gr. P63/mmc, Z = 2), intensity data collection conditions,
and refinement statistics
Composition
NiV0.07Sb0.93
Ni0.93V0.07Sb1.00
a, Å
3.9333(5)
5.1402(6)
68.87(2)
3.9398(4)
5.1408(6)
69.10(2)
c, Å
V, Å3
Calculated density, g/cm3
8.458(3)
8.646(2)
Diffractometer
DRON-3M
Radiation, wavelength
Absorption coefficient, cm–1
[001] texturing factor
Refinement parameters
Refinement procedure
2θmax, deg; sinθmax/λ, Å–1
Atomic positions
Cu, λ = 1.54185 Å
1642.33
0.7400
1739.56
3.7(4)
3
Full profile
97.89; 0.489
97.89; 0.489
2
Site composition; thermal parameter, Å2
Ni in 2a; B = 0.7(4)
0.93(5)Sb + 0.07(5)V in 2c; B = 0.5(3)
0.0249; 0.1545
0.90(3)Ni + 0.10(3)V in 2a; B = 0.7(4)
Sb in 2c; B = 1.0(2)
RI; Rp
0.0650; 0.1146
It can be seen from Table 1 that the lattice parame- slightly smaller than those of the respective binary
ters of Ni5Sb2 vary across its homogeneity range. The compounds (Table 1), which also attests to dissolution
of the third component (V and Ni, respectively).
To determine vanadium solubility in NiSb, we pre-
pared samples containing 5 or 10 at % V and 44, 46, or
variation is somewhat larger in three-component sam-
ples, attesting to a slight solubility of vanadium in
Ni5Sb2. Since the samples containing 4 at % V were
two- or three-phase, we conclude that the solubility of 51 at % Sb. The samples containing 5 at % V were
vanadium in Ni5Sb2 is within 4 at %.
nearly single-phase (trace levels of additional phases).
At a vanadium content of 10 at %, the samples were
two- or three-phase. The solubility limit was deter-
mined by refining the crystal structure of NiSb (NiAs
type) from powder XRD data for the samples contain-
In three-component samples, the lattice parameters
of the NiSb phase (Ni1 – xSbx) were slightly larger and
the lattice parameters of the VSb phase (V1 – xSbx) were
0.087
0.087
0.085
0.086
(a)
(b)
(c)
0.085
0.084
0.083
0.55
0.083
0.55
0.082
0.55
1
2
3
0.54
0.43
0.54
0.43
0.54
0.43
0.42
0.42
V
0.42
0.1
0.2
0.3
x
0.1 0.2 0.3
0.1
0.2
0.3
x
0.4
V1.04–xNixSb0.96
1.00–xNixSb
x
V1.0–0.5xNixSb1.0–0.5x
Fig. 3. Composition dependences of lattice parameters for solid solutions of Ni in VSb along the (a) V
Ni Sb
,
0.96
1.04 – x
x
(b) V
Ni Sb
, and (c) V
Ni Sb
lines: (1) single-, (2) two-, and (3) three-phase samples.
1.00 – x
x
1.00
1.0 – 0.5x
x
1.0 – 0.5x
INORGANIC MATERIALS Vol. 43 No. 6 2007

612
LOMNYTSKA, PAVLIV
(a)
(b)
NiAs(VSb)
(c)
Ni2In(VNi0.26Sb)
Mg
In(Sb)
Ni(V)
Ni
As(Sb)
Ni(V)
Mg
y
x
Fig. 4. Relationships between the hcp (Mg type), NiAs, and Ni In structures.
2
ing 5 at % V (nominal composition) and 44 or 46 at % atoms only partially, i.e., it has a defect Ni2In structure.
Sb. The results (Table 2) indicate that NiSb dissolves no
more than 3.5 at % V.
We also evaluated nickel solubility in VSb. Since VSb
has a narrow homogeneity range (V1.04–1.00Sb0.96–1.00), we
prepared samples containing 42, 44, 46, 48, and 50 at %
The NiAs and Ni2In structures types can be derived
from the hcp structure (Mg type): filling the octahedral
interstices of the hcp structure gives the NiAs type, and
filling the double tetrahedral interstices leads to the
Ni2In type (Fig. 4). This led us to assume that nickel
Sb. Ni solubility was determined from the composition atoms can be incorporated into the double tetrahedral
dependences of lattice parameters along the interstices of the VSb (NiAs) structure to form
V1.04 − xNixSb0.96 and V1.00 – xNixSb1.00 lines (Figs. 3a, 3b).
As seen, the solubility limits are 7 and 6 at % Ni at Sb
contents of 48 and 50 at %, respectively. The lattice
parameters at these limits of the solid solution are given
in Table 1.
V1 − 0.5xNixSb1 – 0.5x solid solutions. To validate this
assumption, we determined the crystal structures of the
solid solutions in the single-phase samples
V
0.45Ni0.12Sb0.43 and V0.43Ni0.15Sb0.42 by powder XRD,
using the Ni2In structure as the input model (Table 3).
XRD examination of three-component samples The results demonstrate that positions 2a (000) and 2c
showed that the V0.45Ni0.12Sb0.43 and V0.43Ni0.15Sb0.42
samples were nearly single-phase and consisted of the
VSb phase. In a recent study, Lewis et al. [4] deter-
mined the crystal structure of the VNi0.26Sb phase by
(1/3 2/3 1/4) are occupied by the V and Sb atoms and
that position 2d (1/3 2/3 3/4) in the Ni2In structure is
partially occupied by the Ni atoms. Therefore, nickel
incorporation into the VSb phase (NiAs) leads to the
single-crystal XRD. According to their results, position formation of a defect Ni2In structure. The composition
2d (sp. gr. P63/mmc) in this phase is occupied by nickel
dependences of lattice parameters for the
Table 3. Crystal data for V0.90Ni0.24Sb0.86 and V0.86Ni0.30Sb0.84 (sp. gr. P63/mmc, Z = 2), intensity data collection conditions,
and refinement statistics
Composition
V0.90Ni0.24Sb0.86
V0.86Ni0.30Sb0.84
a, Å
4.2380(4)
5.4467(6)
84.72(2)
4.2134(6)
5.4225(8)
83.31(6)
c, Å
V, Å3
Calculated density, g/cm3
7.375(2)
7.272(2)
Diffractometer
DRON-3M
Radiation, wavelength
Absorption coefficient, cm–1
Texturing factor
Cu, λ = 1.54185 Å
1542.47
1720.44
[1 0 0] 1.71
[0 0 1] 0.4212
Refinement parameters
Refinement procedure
2θmax, deg; sinθmax/λ, Å–1
Atomic positions
4
Full profile
110.77; 0.534
111.45; 0.536
4
Site composition; thermal parameter, Å2
V in 2a; B = 2.6(5)
Sb in 2c; B = 2.7(3)
V in 2a; B = 3.7(5)
Sb in 2c; B = 3.3(9)
0.35(4)Ni in 2d; B = 4.4(2)
0.0573; 0.2728
0.27(2)Ni in 2d; B = 1.6(12)
RI; Rp
0.0572; 0.2603
INORGANIC MATERIALS Vol. 43 No. 6 2007

PHASE EQUILIBRIA IN THE V–Ni–Sb SYSTEM
613
V1 − 0.5xNixSb1 – 0.5x solid-solution system (Fig. 3c) indi- 0.110 nm, rAs = 0.125 nm, rSb = 0.182 nm; χP = 2.10,
cate that the solid solution extends to the composition χAs = 2.08, χSb = 1.82 [7]). It is, therefore, reasonable to
V
0.78Ni0.44Sb0.78. Thus, Ni dissolution in VSb involves
expect that the as yet unexplored system V–Ni–Bi also
both Ni substitution for V and partial incorporation of contains no compounds.
Ni atoms into position 2d. The VNi0.26Sb phase
reported by Lewis et al. [4] seems to belong to the solid-
solution system in question.
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In our preparations at 1070 K, we failed to obtain
(by sintering in several steps or arc melting) the VNiSb
phase (MgAgAs structure type) [1] and the V0.6NiSb
phase (presumably, Ni2In structure) [3] (the composi-
tion was inferred from the unit-cell volume). It may be
that V0.6NiSb is formed under other conditions or has a
different composition: its lattice parameters (a =
0.4217 nm, c = 0.5398 nm [3]) differ very little from
those at the limit of the V1 – 0.5xNixSb1 – 0.5x solid solution
(Table 1). Thus, we identified no ternary compounds in
the V–Ni–Sb system at 1070 K.
The absence of ternary compounds in the V–Ni–Sb
system and the formation of solid solutions based on
binary compounds seem to be associated with both the
low reactivity of antimony and the small difference in
electronegativity and atomic size between the constitu-
ent transition metals (rV = 0.1321 nm, rNi = 0.1246 nm;
χV = 1.63, χNi = 1.75 [7]). The phase relations in the
V−Ni–Sb system are similar to those in systems with
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the V–Mn–Sb system contains substitutional solid
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composition range. The systems V–Fe(Co)–Sb contain
the compounds VFeSb and VCoSb with the MgAgAs
structure, which undergo a high-pressure transition to
the Ni2In structure [2]. The phase relations in the
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formed by two transition metals and a Group V-A p ele-
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from phosphorus (three compounds [11]) to arsenic
(one compound [8]) and to antimony (no compounds).
This is due to the reduction in the electronegativity of
the p element and the increase in its atomic radius (rP =
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INORGANIC MATERIALS Vol. 43 No. 6 2007