ChemInform Abstract: Phase Equilibria in the AgGaS₂—GeS₂ System.

Abstract

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Single crystal preparation and properties of the AgGaGeS4–AgGaGe3Se8 solid solution

“…However, the small difference between the liquidus and solidus temperatures is quite important for the single crystal growth technology of the solid solution, as it permits to produce crystals with negligible composition variation along the grown crystal. As to end compositions, melting temperature determined for AgGaGeS 4 is T¼112975 K that well relates to earlier result T¼1133 K [11] and is noticeably higher the values T¼1118, 1113, and 1121 K reported in Refs. [10,14,18], respectively.…”

“…The quaternary g-phase that forms in the AgGaSe 2 -GeSe 2 system exists in the range of 65-88 mol% GeSe 2 at T ¼720 K with the melting point maximum at T¼995 K, which corresponds to the composition AgGaGe 3 Se 8 (space group Fdd2; a ¼1.2431, b¼2.3806, c ¼0.7135 nm) [13]. The crystals of AgGaGeS 4 and of the g-phase selenide were obtained by many authors and their properties were extensively reported [10][11][12][13][14][15][16][17][18][19][20][21][22]. As AgGaGeS 4 and AgGaGe 3 Se 8 are isostructural with minor differences in the ionic radii of the interchangeable elements (for a case of isovalent substitution), one can expect the formation of considerable solid solution ranges between these two compounds.…”

“…The AgGaGeS 4 compound forms in the AgGaS 2 -GeS 2 system as an intermediate phase with the homogeneity region 48-57 mol% GeS 2 at temperature T¼720 K) and melts congruently at T¼ 1136 K [11]. The thiogermanate AgGaGeS 4 crystallizes in the non-centro symmetric space group Fdd2 with the unit cell parameters a ¼1.2028, b¼ 2.2918, c¼0.6874 nm (for the stoichiometric composition) [12].…”

Magnetooptic rotation and thermal expansion of AgGaGeS4 crystals

“…The quaternary sulphide AGGS melts congruently [13], which enables oriented crystallization when growing single crystals. At the same time, Chbani et al [14] have shown that Ag 2 S-Ga 2 S 3 -GeS 2 system in which the quaternary compound appears reveals a large region of glass formation. This indicates high viscosity of the melts of this system and, consequently, slow diffusion in the melt.…”

The Ag2S–In2S3–Si(Ge)S2 systems and crystal structure of quaternary sulfides Ag2In2Si(Ge)S6

“…Phase equilibria in the quasi-ternary systems Ag 2 X-B III 2 X 3 -C IV X 2 (B III = Ga, In; C IV = Si, Ge, Sn; X = S, Se) were partially investigated [1][2][3][4][5]. The results show that nearly all compounds form at the AgB III X 2 -C IV X 2 sections with a 2:1 ratio for the quaternary phases Cu 2 In 2 SiS 6 (space group (SG) Cc) [6], Ag 2 In 2 SiSe 6 (SG Cc) [7], Ag 2 In 2 GeSe 6 (SG Cc) [8]; and 1:1 ratio for the phases AgGaGeS 4 (SG Fdd2) [3], AgInSnS 4 (SG Fd3m) [9], Ag 0.735 InGeSe 4 (SG P42c) [10], AgInSnSe 4 [5].…”