Kogut Y. Phase Equilibria and Glass Formation in the Ag2X-PbX-GeX2 (X=S, Se) and Related Systems

The thesis contains the results of the investigation of the phase equilibria and glass formation in quasi-ternary systems based on Ag, Pb(II) and Ge chalcogenides. Isothermal sections of 12 quasi-ternary systems AI2X-PbX-DIVX2 (AI - Ag, Cu; DIV - Si, Ge, Sn; X - S, Se) at 298 K were investigated for the first time. For the Ag2Se-PbSe-GeSe2 system, 8 vertical sections and liquidus surface projection were constructed. Four quaternary compounds (Ag2PbGeS4, Cu2PbSiS4, Cu4PbSi2S7, Ag1.43PbSi1.14S4) were found for the first time; the chemical composition of the quaternary compound СuPb1.5SiSe4 was refined. Electronic structure, optical, photoelectric and non-linear optical properties (second harmonic generation, two-photon absorption, piezoelectric effect) of the single crystals Ag0.5Pb1.75GeS4 and Ag0.5Pb1.75GeS3Se were investigated. Glass formation in 8 quasi-ternary systems Ag2X- BIIX-GeX2 (BII - Zn, Cd, Hg, Pb) was investigated for the first time. Large glass-formation regions were found in the systems Ag2Se-HgSe-GeSe2, Ag2S-HgS-GeS2, Ag2S-PbS-GeS2.