The Se−Sn (Selenium-Tin) system

Se-Sn

The Se-Sn (Selenium-Tin) System 78.96 118.69

By R.C. Sharma and Y.A. Chang University of Wisconsin-Madison

Equilibrium Diagram General Features. Two intermediate compounds, SnSe and SnSe2, are formed in the Sn-Se system. There is a liquid miscibility gap, a monotectic reaction, and a eutectic reaction in the Sn-SnSe region; a eutectic reaction in the SnSe-SnSe2 region; and a eutectic reaction in the SnSe2-Se region of the Sn-Se phase diagram. Figure 1 gives the assessed Sn-Se phase diagram, and Fig. 2 shows the Sn-rich portion of the phase diagram.

Llquldua. The liquidus in the Sn-Se system was determined by [06Pel], [09Pel], [09Bill, [64Vas], and [66Kha]. These da ta are in reasonable agreement with one an- other (Fig. 1 and 2). The liquid miscibility gap in the Sn- Se region and the Se-rich portion of the liquidus have not been determined experimentally and are shown as dotted lines in Fig. 1.

I n t e r m e d i a t e P h a s e s . Based on their thermal analysis data, [09Bill suggested that the intermediate compounds SnSe and SnzSe3 are formed in the Sn-Se system. How- ever, X-ray and meta l lographic work by [66Kha] and MSssbauer studies by [71Bar] showed conclusively tha t the Sn2Se3 compound does not exist in the equilibrium Sn-Se system. Instead, the intermediate phases formed in the system are SnSe and SnSe2.

There is some discrepancy in the l i te ra ture about the melting points of SnSe and SnSe2. The data from different investigations, along with the assessed values, are given in Table 1. For the melting point of SnSe, the value by [66Kha] is suggested. For the melting point of SnSe=, the values given by [Hansen], [77Kul], and [82Ale] are essentially in agreement. [66Kha] reported the melting point of SnSe= to be 675 ~ in the text of his paper; however, his experimental data and plotted phase diagram show a value close to 657 ~ as previously assessed by [Hansen]. Therefore, 657 ~ is suggested for the melting point of SnSe=.

Invarlant Equilibria. The two eutectic points, L~ ~,~ (Sn) + SnSe and L2 ~-- SnSe2 + (Se), are very close to pure Sn and pure Se, respectively, and have not been determined experimentally. In Fig. 1, the eutectic temperatures of

Table 1 Melting Points of SnSe and SnSe2 Melting temperature, "C

Reference SnSe SnSe~

[Hanaen] . . . . . . . . . . . . . . . . . . . . 860 657 [66Kha] . . . . . . . . . . . . . . . . . . . . 880 675 [77Kul] . . . . . . . . . . . . . . . . . . . . --- 656 -+ 2 [82Ale] . . . . . . . . . . . . . . . . . . . . ... 656 +- 2 A~essed . . . . . . . . . . . . . . . . . . . . 880 657

Fig. 1 Assessed Sn-Se Phase Diagram

Weight Percent Selenium 0 I0 20 30 40 50 60 70 BO 90 I00

1 0 0 0 . . . . . . . . I I . . . . . I . _ _ . ~ . ~ L . - . I . . . . . L I . . ~ . . . . . . ~ . . . . . . 1 . . . . . . [ T * ~ j , " ) . . . . l

900

800

700

600 /

500

4OCt

300

200-

100 �9 .

ol" yi

231.11e~l~

~ ~ l ~

�9 --- (an) . . . . . . , . . . . . . . 1 . . . . . .

10 20

Sn

El + Lz \ 880oc x 06Pel,09Ps] ~Ak_ + ogeil

v [ ~ 2 0 66Kha

~ ~ ~

(Se)-- i . . . . . . i . ~ . . . . . i , �9 . - , i . . . i . . . i . . . .

30 40 50 60 70 80 90 lO0 Atomic Percent Selenium Se

Ll

~9 o

E [--

~I~

R.C. Sharma and Y.A. Chang, 1986.

68 Bulletin of Alloy Phase Diagrams Vol. 7 No. 1 1986

Se-Sn

these reactions are shown arbitrarily at -1 ~ below the melting points of pure Sn and pure Se, respectively. The temperatures of the monotectic reaction, L2 ~ LI + SnSe, in the Sn-SnSe region and the eutectic reaction L2 SnSe + SnSe2, were determined by a number of investi- gators. The data are summarized in Table 2, along with the suggested values, 822 and 628 ~ respectively.

Solid Solubilities. The mutual solid solubilities of Sn and Se are very limited. [38Jen] reported the solubility of Se in (flSn) to be 0.05 at.% at 200 ~ There are no reported measurements on the solubility of Sn in (Se).

Phase Transition In SnSe. Based on thermal expansion measurements, [61Zhd] reported a second-order transition in SnSe at 540 ~ The higher-order character of the transition was confirmed apparently by DTA exper- iments [63Dem]. However, [81Ball proposed a first-order polymorphic transition in SnSe somewhere between 490 and 566 ~ on the basis of their heat capacity measurements. [81Ball gave the enthalpy of transformation for this polymorphic change to be 1600 J/mol of SnSe.

The p re l imina ry DTA and DSC resul t s of [85Lin] suggest t ha t SnSe goes th rough a f i r s t -o rde r polymorphic t rans i - t i on a t a t e m p e r a t u r e s o m e w h e r e b e t w e e n 510 a n d 520 ~ A f i r s t - o r d e r p o l y m o r p h i c t r a n s i t i o n in SnSe around - 5 1 5 ~ is, therefore, sugges ted here.

Crystal Structures and Lattice Parameters C r y s t a l s t r u c t u r e and l a t t i c e p a r a m e t e r d a t a for t h e phases in the Sn-Se sys tem are given in Tables 3 and 4, respectively.

Thermodynamics The Liquid Phase. There are no repor ted measu remen t s on the the rmodynamic proper t ies of l iquid Sn-Se alloys. [77Ale] i nve s t i ga t e d the de ns i t y and viscosi ty of Sn-Se liquids over a range of composit ions and tempera tures .

The SnSe Phase. The Gibbs energy of format ion for SnSe was d e t e r m i n e d by [71Mel], by an emf method , in t he

Table 2 Invarlant Equilibria in the Sn-Se System Compositions, aL% Se Temperature ,

Reaction L2 Ll ~ Reference

L2 ~ L1 + SnSe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... - 16 822 [Hansen] 49 - 16 820 [66Kha] . . . . . . 822 [82Ale] 49 ~16 822 Assessed

L2 ~ SnSe + SnSe2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 ... 640 [Hansen] 61 -.. 625 [66Kha] . . . . . . 628 [77Kul, 82Ale] 61 .. . 628 Assessed

Fig. 2 Sn-Rich Region of the Sn-Se Phase Diagram

( .9 o

r~

E [ - .

700-

6 0 0

500

4 0 0

300

200.

1 0 0 .

W e i g h t P e r c e n t S e l e n i u m I

. . . . . . . , �9 ~ . . . . . . . . . T . . . . . . . . . �9 . . . . . . . . . T . . . . ~ . . . . . . . . . T . . . . . . . , . . . .

L1 J /

L1 + S n S e

J

--(Sn) . . . . . . . i . . . . T . . . . . . . T . . . . . . . . . i . . . . . . . . , . . . . . . . . r . . . . . . . . - . i . . . . . . . . . ~ -

025 05 075 1 125 15 175 2 225 z5

Sn A t o m i c P e r c e n t S e l e n i u m


Bulle t in of Alloy Phase Diagrams Vol. 7 No. 1 1986 69

Se-Sn

temperature range 435 to 485 K. They obtained for the reaction Sn(cd) + Se(cd) --* SnSe(cd):

AfG ~ = - 9 5 389 - 3.184 T J/mol of SnSe (Eq 1)

where T is in K (435 K < T < 485 K). From these data, [71Mel] derived the values for AfH~ K) and AFS~ K) for the above reaction. [64Col] determined AfH~ K) for the above reaction from the partial pressure measurements. The enthalpy of melting, A f ~ H , for SnSe was measured by [81Bal] and [82Ale]. These data are summarized in Table 5, along with the assessed values.

Table 3 Sn-Se Crystal Structure Data [Pearson2] Struktur-

Composition, Pearson S p a c e b e r i c h t Phase aL% Se symbol group designation Prototype

(]3Sn) . . . . -0 t/4 141/amd A 5 flSn SnSe . . . . 50 oP8 Pnrna B 16 GeS SnSe2 ... 66.67 hP3 P3rn 1 C6 CdI2 (Se) . . . . . -100 hP3 P3~21 A8 TSe

[74Bla] measured the heat content, H ~ - H~ K), of SnSe from room temperature to 540 ~ [81Bal] and [81Wie] measured the heat capacity, Cp, of SnSe in the temperature ranges 100 to 862 ~ and - 4 0 to 300 ~ respectively. [70Glal] determined the volume change during melting of SnSe, and [70Gla2] determined the viscosity of liquid SnSe as a function of temperature.

SnSe2 Phase. [71Mel] determined the Gibbs energy of formation of SnSe2 by emf measurements in the temperature range 435 to 485 K and obtained for the reaction Sn(cd) + ZSe(cd) --* SnSe2(cd):

AtG ~ = -125 249.5 + 18.873 T J/mol of SnSe2 (Eq 2)

where T is in K (435 K < T < 485 K). From these data, they derived the values for AfH~ K) and AFS~ K) for the above reaction, hfH~ K) for the above reaction was also obtained by [67Kar] from dissociation pressure measurements, and by [77Kul] from equilibrium vapor pressure measurements. [82Ale] determined the enthalpy of melting of SnSe2. These data are summarized in Table

Table 4 Sn-Se Lattice Parameter Data Composition, I L a t t i c e p a r a m e t e r s , n m I

Phase at.% Se a b c R e f e r e n c e

(/3Sn) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~0 SnSe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

. . . . . . [Pearson2] 0.4162 1.149 [61Kre] 0.419 1.157 [56Oka] 0.4178 1.149 [66Kha]

�9 -. 0.6137 [Pearson2] 0.6132 [66Kha] 0.49590 [Pearson2]

0.58315 0.4436 0.446 0.4474

SnSe2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86.67 0.3811 0.3795 .-.

(Se) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -100 0.43656 ---

Fig. 3 P-T Diagram for the Sn-Se System

- l .

L, - 2

- 3 2

- 4

- 5

- 6 07

L1 "'",,,

T . . . . . . . . . . 0 8 0 9 i I I I 2 I 3 I ~ I 5

1000/T(K)



Se-Sn

Table 5 Thermodynamic Properties of SnSe and SnSe2 Enthalpy Entropy Enthalpy of

[-AH~ K)], [A S~ K)], fusion (At.. H), Reaction kJ/mol J/mol �9 K kJ/mol Reference

Sn(cd) + Se(cd) ~ SnSe(cd) . . . . . . . . . . . . . . . . . 94.96 5.02 .-- [71Mel] 89.96 . . . . . . [64Col]

. . . . . . 32.8 [81Bal]

. . . . . . 41.87 [82Ale] 92.26 5.02 37.34 Assessed

Sn(cd) + 2So(cd) ~ SnSe2(cd) . . . . . . . . . . . . . . . 124.68 -17.15 ... [71Mel] 153.3 . . . . . . [67Karl 108.78 . . . . . . [77Kul]

. . . . . . 76.5 [82Ale] 124.68 - 17.15 76.5 Assessed

5, along with the assessed values. [81Wie] measured the hea t capacity, Cp, for SnSe2 from - 4 0 to 300 ~

V a p o r P r e s s u r e . [61Nes], [63Hir], [64Col], and [70Bla] measured the vapor p re s su re of SnSe(g) in equ i l i b r ium with SnSe(cd). Table 6 gives p [SnSe(g)] in equ i l i b r i um with SnSe(cd) from di f ferent inves t iga t ions , a long with chosen values, based on a previous eva lua t ion by [74Mil]. [64Col] also observed the presence of Se2(g) and Sn2Se2(g) in the vapor phase, in equ i l ib r ium wi th SnSe(cd). They measured the Sn2Se2(g) ~ 2 SnSe(g) equ i l ib r ium in the t empera tu re range 660 to 700 ~ and found AH~ K) for the above react ion to be 194.6 +- 20 kJ/mol, based on an es t imate of 173.64 J /mol . K for -{AG~ - AH~ K)/T}.

[77Kul] and [82Ale] m e a s u r e d the p a r t i a l p r e s s u r e of SnSe2(g) in equ i l ib r ium wi th SnSe2(cd) and summar ized their resul ts as:

-9670(+400) log Ps,s~ (bar) - T + 8.03(-+0.43) (Eq 3)

where T is in K.

Pressure-Temperature Diagram. [68Gas], [77Kul], and [82Ale] d e t e r m i n e d the p r e s su re - t empe ra tu r e - compos i - tion d iag ram for the Sn-Se system. Thei r da t a a re general ly consistent. F igure 3 shows the P-T projection of the P-T-x d iag ram t aken from [82Ale]. In Fig. 3, to ta l vapor pressure is p lo t ted a g a i n s t reciprocal t empe ra tu r e . The vapor phase , in genera l , consis ts of SnSe(g), Sn2Se2(g), SnSe2(g), Se2(g), and o ther Sen (n = 1 to 8) species. How- ever, for Se content g r e a t e r t h a n 50 at.%, Se2(g) is the major species in the vapor phase.

Cited References 06Pel : H. Pelabon and H. Moissan, "On the Sulphides, Se-

lenides, and Tellurides of Tin," C.R. Hebd. Seances Acad. Sci. , 142, 1147-1149 (1906) in French. (Equi Diagram; Experimen- tal; #)

09Bil: W. Biltz and W. Mecklenburg, "A Study of the Phase Dia- gram of Sn with S, Se and Te," Z. Anorg. Chem., 64,226-235 (1909) in German. (Equi Diagram; Experimental)

09Pel: H. Pelabon, "On the Fusibility of Alloys of Sulfur, Sele- nium, and Tellurium with Some Metal," Ann. Chim. Phys., 17, 526-566 (1909) in French. (Equi Diagram; Experimental; #)

38Jen: E. Jenckel and L. Roth, "The Solubility of a Few Metals in Tin and Their Effect Upon the Recovery Temperature," Z. Metallkd., 30, 135-144 (1938) in German. (Equi Diagram: Experimental)

58Oka: A. Okazaki and I. Ueda, "The Crystal Structure of Stan- nous Solenide, SnSe," J. Phys. Soc. Jpn., 11,470 (1956). (Crys Structure, Thermo; Experimental)

Table 6 Partial Pressure of SnSe(g) in Equilibrium with SnSe(cd)

log(p, bar) = - A / T + B Reference Method A B

[63Hir] . . . . . . . . . . . Knudsen effusion 10495 7.324 [61Nes] . . . . . . . . . . Knudsen effusion 9187 5.821 [64Col] . . . . . . . . . . . Mass spectrometry 10 380 7.356 [70Bla] . . . . . . . . . . . Torsion effusion 10 690 7.479 Assessed(a) . . . . . . . . . . 10 746 7.676

(a) 700 K < T < 1100 K.

61Kre: H. Krebs, K. Gruen, and D. Kallen, "Structures and Properties of Metalloids. XIV. Mixed Crystal Systems Be- tween Semiconducting Chalcogenides of the Fourth Group," Z. Anorg. Chem., 312,307-313 (1961). (Crys Structure; Exper- imental)

61Nes: Y.M. Nesterova, A.S. Pashinkin, and A.V. Novoselova, "Determination of the Saturated Vapor Pressure of Solid Tin Selenide and Telluride," Zh. Neorg. Khim., 6(9), 2014-2018 (1961) in Russian; TR: Russ. J. Inorg. Chem., 6(9), 1031-1033 (1961). (Crys Structure, Thermo; Experimental)

61Zhd: V.V. Zhdanova, "A Phase Transition of the Second Kind in SnSe," Fiz. Tverd. Tela., 3(5), 1619-1620 (1961) in Russian; TR: Soy. Phys. Solid State, 3(5), 1174-1175 (1961). (Equi Dia- gram; Experimental)

63Dem: S.A. Dembovskii, B.N. Egorov, A.S. Pashinkin, and Y.A. Polyakov, "Phase Transformation of the Second Order in Snso," Zh. Neorg. Khim., 8(4), 1025-1026 (1963) in Russian; TR: Russ. J. Inorg. Chem., 8(4), 530-531 (1963). (Equi Dia- gram; Experimental)

63Hi t : C. Hirayama, Y. Ichikawa, and A.M. DeRoo, "Vapor Pressures of Tin Selenide and Tin Telluride," J. Phys. Chem., 67, 1039-1042 (1963). (Thermo; Experimental)

64Co1: R. Colin and J. Drowart, "Thermodynamic Study of Tin Selenide and Tin Tellurium Using a Mass Spectrometer," Trans. Faraday Soc., 60, 673-683 (1964). (Thermo; Exper- imental)

64Vas: T.V. Vasilenko and Y.I. Khar'kov, "Diffusion and Solu- bility of Selenium in Molten Tin," Fiz. Met. Metalloved., 18(2), 203-209 (1964) in Russ ian; TR: Phys. Met. Metallogr. (U.S.S.R.), 18(2), 45-50 (1964). (Equi Diagram; Experimental)

* 6 6 K h a : M.I. K h a r a k h a n o v a , A.S. Pa sh ink in , and A.V. Novoselova, "On the Fusibility Diagram of the Tin-Selenium System," Izv. Akad. Nauk SSSR, Neorg. Mater., 2, 1186-1189 (1966) in Russian. (Equi Diagram, Crys Structure; Exper- imental; #)

6 7 K a r : M.I. K a r a k h a n o v a , A.S. P a s h i n k i n , and A.V. Novoselova, "Determining the Dissociation Pressure of Solid Tin Diselenide," Izv. Akad. Nauk SSSR, Neorg. Mater., 3(9), 1550-1554 (1967) in Russian; TR: Inorg. Mater., 3(9), 1352- 1355 (1967). (Thermo; Experimental)

*68Gas: A.M. Gas'kov, V.P. Zlomanov, Y.A. Sapozhnikov, and A.V. Novoselova, '~rhe Tin-Selenium Phase Diagram," Vestn. Mosk. Univ. Khim., 23(3), 48-51 (1968) in Russian; TR:

Bul le t in of Alloy Phase Diagrams Vol. 7 No. 1 1986 71

Se-Sn Sn-Te

Moscow Univ. Chem. Bull., 23(3), 30-32 (1968). (Equi Dia- gram, Thermo; Experimental; #)

70Bla: R.C. Blair and Z.A. Munir, "Sublimation Coefficient of Tin Selenide," J. Am. Chem. Soc., 53(6), 301-303 (1970). (Thermo; Experimental)

70Glal: V.M. Glazov and O.V. Situlina, 'Temperature Variation in Short-Range Structure of Molten Germanium and Tin Sul- fide and Selenide," Zh. Fiz. Khim., 44(10), 2480-2485 (1970) in Russian; TR: Russ. J. Phys. Chem., 44(10), 1406-1409 (1970). (Thermo; Experimental)

70Gla2: V.M. Glazov and O.V. Situlina, "Volume Changes in the Fusion of Germanium and Tin Sulfides and Selenides," Zh. Fiz. Khim., 44(8), 2018-2021 (1970) in Russian; TR: Russ.J. Phys. Chem., 44(8), 1140-1143 (1970). (Thermo; Ex- perimental)

71Bar: G.M. Bartenev, A.D. Tsyganov, S.A. Dembovskii, and V.I. Mikhailov, "M6ssbauer-Effect Study of the Systems Sn-S and Sn-Se," Izv. Akad. Nauk SSSR, Neorg. Mater., 7(6), 1442- 1443 (1971) in Russian; TR: Inorg. Mater., 7(8), 1280-1281 (1971). (Equi Diagram; Experimental)

*71Meh B.T. Melekh, N.B. Stepanova, T.A. Fomina, and S.A. Semenkovich, "Thermodynamic Properties of Compounds in the Tin-Selenium System," Zh. Fiz. Khim., 45(8), 2018-2020 (1971) in Russian; TR: Russ. J. Phys. Chem., 45(8), 1144-1145 (1971). (Thermo; Experimental)

74Bla: R. Blachnik, R. Igel, and P. Wallbrecht, '"thermodynamic Properties of Tin Chalcogenides," Z. Naturforsch., 29a, 1198- 1201 (1974) in German. (Thermo; Experimental)

74Mih K.C. Mills, Thermodynamic Data for Inorganic Sulfides, Selenides and Tellurides, Butterworths, London (1974).

77Ale: A.A. Aleksandrov., T.N. Andrianova, V.S. Okhotin, L.A. Razumeichenko, and Z.I. Panina, "Investigation of the Density and Viscosity of Melts of the Tin-Selenium System," Teplofiz. Vys. Temp., 15(1), 47-52 (1977) in Russian; TR: High Temp. Sci., 15(1), 40-44 (1977). (Thermo; Experimental)

77Kuh E.A. Kulyukhina, V.P. Zlomanov, and A.V. Novoselova, "P-T Projection of the Phase Diagram of the System SnSe-Se," Izv. Akad. Nauk SSSR, Neorg. Mater., 13(2), 237-240 (1977) in Russian; TR: Inorg. Mater., 13(2), 200-203 (1977). (Equi Di- agram, Thermo; Experimental)

81Bah L. Balde, B. Legendre, C. Souleau, P. Khodadad, and J.R. Didry, "Heat Capacity of the Alloy Sno.sSeos in the Solid State Between 375 and 1135 K," J. Less-Common Met., 80, 43-50 (1981) in French. (Therrno; Experimental)

81Wie: H. Wiedemeier, G. Pultz, U. Gaur, and B. Wunderlich, "Heat Capacity Measurements of SnSe and SnSe2," Ther- mochim. Acta, 43,297-303 (1981). (Thermo; Experimental)

*82Ale: E.A. Aleshina, V.P. Zlomanov, and A.V. Novoselova, "Investigation of the P-T-x Diagram of the Sn-Se System," Izv. Akad. Nauk SSSR, Neorg. Mater., 18(6), 913-916 (1982) in Russian; TR: Inorg. Mater., 18(6), 765-767 (1982). (Equi Di- agram, Thermo; Experimental; #)

85Lin: J.-C. Lin and Y.A. Chang, unpublished research, Univ. of Wisconsin, Madison (1985).

*Indicates key paper. #Indicates presence of a phase diagram.

Sn-Se evaluation contributed by R.C. Sharma and Y.A. Chang, Department of Metallurgical and Mineral Engineering, University of Wisconsin, 1509 University Avenue, Madison, Vil 53706. This work was supported by the American Society for Metals. Literature searched through 1984. R.C. Sharma is Visiting Assistant Professor, 1984-86, on leave from Indian Institute of Technology, Kanpur, U.P. 208016 India. Professor Chang is the ASM/NBS Data Program Category Editor for binary Group II-VI and III-V aUoys.

The Sn-Te (Tin-Tellurium) System 118.69 127.60

By R.C. Sharma and Y.A. Chang University of Wisconsin-Madison

Equilibrium Diagram General Features. In the Sn-Te system, an intermediate phase, SnTe, with a narrow range of homogeneity is formed around 50 at.% Te, and two eutectic reactions occur, one each in the Sn-SnTe and SnTe-Te portions of the phase diagram. The assessed phase diagram in Fig. 1 is from [83Hsi]. Figure 2 shows the Sn-rich liquidus, and Fig. 3, the homogeneity range of the intermediate phase, SnTe, at high temperature [86Lin].

Liquidus. The melting points of Sn and Te are 231.9681 and 449.57 ~ respectively [Melt]. The liquidus in the Sn-Te sys tem was de t e rmined by [09Bil], [11Kob],

Table 1 Assessed Sn-Te Liquidus Composition, Temperature, Composition, Temperature,

at.% Te ~ at.% Te ~

0 . . . . . . . . . . . . . . 231.9681 10 . . . . . . . . . . . . . . 661 20 . . . . . . . . . . . . . . 708 30 . . . . . . . . . . . . . . 728 40 . . . . . . . . . . . . . . 756 50.44 . . . . . . . . . . . . . 806

60 . . . . . . . . . . . . . . . 715 70 . . . . . . . . . . . . . . . 591 80 . . . . . . . . . . . . . . . 466 90 . . . . . . . . . . . . . . . 420

100 . . . . . . . . . . . . . . . 449.57

[68Poo], [75Har], [77Leb], [80Kur], and [81Rak]. The assessed liquidus is shown in Fig. 1 and 2, along with the experimental data. The data from [80Kur] are not avail- able in numerical form, but they are in general agreement with the assessed liquidus. Table 1 gives selected liquidus data. [82Kha] calculated the Sn-Te liquidus by an ideal associated solution model assuming the presence of "SnTe."

Eut~t ic Reactions. Two eutectic reactions occur in the Sn-Te system. The eutectic point in the SnTe-Te region was determined by [09Bil], [11Kob], [77Leb], [80Kur], and [81Rak]. The eutectic point in the Sn-SnTe region is very close to pure Sn and has not been determined experimentally. The calculated value of [83Hsi] is suggested. Table 2 gives the eutectic points from different investigations, along with the assessed values.

Solid Solubilities. The mutual solid solubilities of Sn and Te are very limited. [38Han] reported the solubility of Te in (flSn) to be 0.11 at.% at 230 ~ and 0.07 at.% at 20 ~ whereas [38Jen] reported it to be -0.025 at.% at 200 ~ [70Aba] determined the solubility of Sn in (Te) to be 0.01 at.% at room temperature.


The Se−Sn (Selenium-Tin) system

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