METAL SULFIDE TETRAPHOSPHORUSDEKASULPHIDE PHASE-DIAGRAMS

The phase diagrams of the quasibinary systems Ag2S-P4S10, Cu2S-P4S10, Tl2S-P4S10 and Sb2S3-P4S10 were determined by means of difference thermal and X-ray analyses. Ag2S-P4S10 contains the congruently melting compound Ag7PS6, the peritectic compounds Ag3PS4, Ag4P2S7 and Ag2P2S6 and the peritectoid high temperature Compound Ag7P3S11. The lattice parameters of Ag3PS4 and of a new high temperature modification of Ag4P2S7 were determined: Ag3PS4, space group Pmn2(1), a = 765.0(1), b = 686.8(1), c = 650.9(1) pm; HT-Ag4P2S7, a = 807.3(2), b = 1102.2(3), c = 636.8(2) pm, beta = 105.22(3)-degrees. In the system Cu2S-P4S10 the congruently melting compound Cu7PS6, the peritectic compound Cu3PS4 and the new metathiophosphate (CuPS3)n were observed. The IR and Raman spectra of the compounds are given. The systeMS Tl2S-P4S10 and Sb2S3-P4S10 are simple. Similar to the system Ag2S-P4S10, miscibility gaps were found on the P4S10-rich side of these systems. The compounds Tl3PS4, Tl2P2S6 and SbPS4 (lattice parameters a = 1306.03(5), c = 627.9(5) pm) melt congruently.