PHASES AND PHASE-RELATIONS IN THE CU-TE-S SYSTEM AT TEMPERATURES BETWEEN 350-DEGREES-C AND 900-DEGREES-C

Phase relations were determined in the Cu-Te-S system at 350-degrees, 450-degrees, 550-degrees, 675-degrees, 800-degrees and 900-degrees-C. At 350-degrees-C three ternary phases are present, goldfieldite and tw o phases A and B, which have not been found in nature. Phase A has dis appeared by 450-degrees-C, goldfieldite has disappeared by 550-degrees -C, and phase B has disappeared by 800-degrees-C. Goldfieldite (Cu10.2 3Te4.12S13.00) and phase A (Cu5Te4S8) have no detectable compositional ranges. Goldfieldite has a cubic, face centered cell with a(o) = 10.2 42(22) angstrom. Phase A is monoclinic primitive, a(o) = 6.51 angstrom , b(o) = 3.72 angstrom, c(o) = 18.11 angstrom, beta = 90.84-degrees an d Z = 1. Phase B has a long and narrow compositional field at all temp erature levels with nearly constant Cu content and an ideal formula ba sed on 16 atoms is Cu10(Te6-xSx) With 0.4>x>3.3 and Z = 10. The phase is cubic body centered with a(o) ranging from 14.337(103) angstrom (S- poor) to 14.827(60) angstrom (S-rich). X-ray powder data and optical d ata on phases A and B are listed. At 350-degrees-C there exist two liq uid fields which at 450-degrees-C have become one continuous field str etching from Cu45Te55 with low S content to the tellurium corner of th e phase diagram and from there to the sulphur corner. With increasing S, the Cu content of the liquid rapidly decreases to trace amounts. Wi th increasing temperature the field extends into the ternary from the tellurium corner towards the Cu-S join. The boundary of the liquid fie ld in the central portion of the phase diagram towards the sulphur cor ner does not change position with an increase in temperature from 550- degrees to 900-degrees-C.