PD-SB-TE MINERALS IN THE SYSTEM PD-SB-TE

Phase relations in the system Pd-Sb-Te were investigated at 1000, 800, and 600^oC, using the sealed capsule technique. The quenched run products were studied by reflected light microscopy, X-ray diffraction, electron microprobe analysis, and differential thermal analysis. At 1000^oC, the solid phases Pd, Pd₂₀Sb₇, Pd₈Sb₃ (mertieite II), Pd₃₁Sb₁₂, and Pd₅Sb₂ are stable with a liquid phase that occupies most of the isothermal diagram. Additional solid phases at 800^oC are Pd₅Sb₃, PdSb (sudburyite), Pd₈Te₃, Pd₇Te₃, and a continuous Pd₂₀Sb₇-Pd₂₀Te₇ solid solution. At 600^oC, PdSb₂, Pd₁₇Te₄, Pd₉Te₄ (telluropalladinite), PdTe(kotulskite), PdTe₂(merenskyite), Sb₂Te₃(tellurantimony), and Sb and continuous PdSb-PdTe and PdSb₂-PdTe₂ solid solutions are stable. All the solid phases exhibit solid solutions, mainly by substitution between Sb and Te to an extent that varies with temperature of formation. The maximum substitution (at.%) of Te for Sb in the Pd-Sb phases is: 44.3 in Pd₈Sb₃, 52.0 in Pd₃₁Sb₁₂, 46.2 in Pd₅Sb₂ at 800^oC; 15.3 in Pd₅Sb₃, 68.3 in PdSb₂ at 600^oC. The maximum substitution (at.%) of Sb for Te in the Pd-Te phases is 34.5 in Pd₈Te₃ at 800^oC, and 41.6 in Pd₇Te₃, 5.2 in Pd₁₇Te₄, 12.4 in Pd₉Te₄, and 19.1 in PdTe₂ at 600^oC. X-ray powder diffraction data show the synthetic PdSb₂ phase to be cubic, probably with space group P2₁3. Testibiopalladite, ideally PdSbTe, may be a member of the PdSb₂-Pd(Sb_0.32Te_0.68)₂ solid solution series. Borovskite(Pd₃SbTe₄) has not been found in the synthetic system over the temperature range 1000-600^oC.