ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2009, Vol. 54, No. 11, pp. 1839–1843. © Pleiades Publishing, Inc., 2009.
Original Russian Text © Ya.I. Dzhafarov, M.B. Babanly, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 11, pp. 1920–1924.
PHYSICOCHEMICAL ANALYSIS
OF INORGANIC SYSTEMS
Tl2S–Sb2S3–Bi2S3 Quasi-Ternary System
Ya. I. Dzhafarov and M. B. Babanly
Baku State University, Baku, Azerbaijan
Received May 5, 2008
Abstract—The Tl2S–Sb2S3–Bi2S3 quasi-ternary system (systemA) was studied using DTA, X- ray powder dif-
fraction, microstructure examination, and microhardness measurements. TlSbS2–Tl4Bi2S5(TlBiS2, Bi2S3),
Sb2S3–TlBiS2, Tl3SbS3–TlBiS2(Bi2S3), and [TlSb0.5Bi0.5S2]–Tl2S isopleths; isothermal sections at 500 K; and liq-
uidus surface projection of system A were constructed. Characteristic features of the title system are extensive
fields of solid solutions extended along the TlSbS2–TlBiS2 quasi-binary section and a continuous solubility belt
1–2 mol % wide extended along the Sb2S3–Bi2S3 binary subsystem. Primary separation fields of phases and the
types and coordinates of invariant and monovariant equilibria in system A were determined.
DOI: 10.1134/S0036023609110254
Search for new multicomponent phases and devel- components in liquid and solid states without extremes
opment of electronic materials on their base require on the liquidus and solidus curves.
studying phase equilibria in the relevant systems. In
Thallium thiostibnites and thiobismuthites have the
this context, quasi-ternary planes of such systems con-
following structures and crystal parameters: Tl3SbS3
taining binary and ternary allied compounds are of
(rhombohedral space group R3m, a = 9.552 Å, c =
7.306 Å) [9], TlSbS2 (rhombohedral space group R3m,
a= 9.519 Å, c = 7.364 Å) [10], TlSb3S5 (monoclinic
space group P21/c, a = 7.225 Å, b = 15.547 Å, c = 8.946
most interest on account of possible formation of exten-
sive solid solutions.
This work continues our studies [1–3] concerning
the search for and creation of physicochemical funda-
Å, α = 113.54°), TlSb5S8 (monoclinic space group Pn,
mentals for the preparation of four-component phases
a = 8.098 Å, b = 19.415 Å, c = 9.059 Å, α = 91.96°) [9],
of variable composition based on thallium, antimony,
and bismuth chalcogenides. Here, our efforts were
focused on phase equilibria in the Tl2S–Sb2S3–Bi2S3
system (system A).
TlBiS2 (hexagonal space group R3 m, a = 4.12 Å, b =
21.9 Å) [11], Tl4Bi2S5 (orthorhombic space group
Pnma62, a = 16.760 Å, b = 4.09 Å, c = 17.396 Å, Z = 4)
[12].
Physicochemical parameters of the starting com-
pounds of system A are found in [4, 5]. The compounds
Tl2S, Sb2S3, and Bi2S3 melt congruently at 723, 819, and
1050 K, respectively. The Tl2S structure is rhombohe-
dral (CdI2 antitype): a = 12.22 Å, c = 18.21 Å, space
Earlier [13], Dzhafarov studied phase equilibria in
system A within the TlSbS2–TlBiS2–Bi2S3–Sb2S3
region. TlSbS2–TlBiS2 (Bi2S3) and Sb2S3–TlBiS2 isop-
leths and a 500-K isotherm of the phase diagram were
constructed, as well as the liquidus surface projection
for this subsystem. The TlSbS2–TlBiS2 isopleth was
group R3 –C23i. Sb2S3 and Bi2S3 crystallize in orthor-
16
hombic system (space group Pbmn–D ) with the shown to be quasi-binary and eutectic with incomplete
2h
terminal solid solutions. The eutectic contains 86 mol %
TlSbS2 and melts at 740 K. The homogeneity regions of
the terminal solid solutions based on TlSbS2 (γ1) and
TlBiS2 (γ2) at the eutectic temperature have maximal
extents of 0–10 and 68–100 mol % TlBiS2, respectively.
The homogeneity regions narrow with decreasing tem-
perature, at 500 K being 0–7 and 72–100 mol % TlBiS2,
respectively.
parameters a = 11.20 Å, b = 11.28 Å, c = 3.83 Å and
a = 11.13 Å, b = 11.27 Å, c = 3.97 Å, respectively.
The Tl2S–Sb2S3, Tl2S–Bi2S3, and Sb2S3–Bi2S3
boundary subsystems of system A were studied earlier
[4, 6–8].
The Tl2S–Sb2S3 [6, 7] and Tl2S–Bi2S3 [8] quasi-
binary systems form several compounds, some melting
congruently (Tl3SbS3 (610 ä), TlSbS2 (755 ä), and
TlBiS2 (1040 K)) and the others incongruently (TlSb3S5
(683 ä), TlSb5S8 (693 ä), and Tl4Bi2S5 (820 K)).
EXPERIMENTAL
Sb2S3–Bi2S3 [4] is also a quasi-binary section; its
phase diagram shows the complete solubility of the
For use in the phase diagram design for the
Tl2S−Sb2S3–Bi2S3 system (system A), binary com-
1839