Exploratory studies of the Cu–Pd–Se system at 650 °C, 550 °C, 400 °C, and 300 °C

The condensed-phase system Cu–Pd–Se was investigated by means of dry syntheses from elements in evacuated silica glass tubes at 650 °C, 550 °C, 400 °C, and 300 °C. Synthetized phases were analysed by electron microprobe and textural studies in polished sections. At 650 °C an extensive selenide liquid field covers central portions of the system, coexisting with a limited choice of Pd selenides, Cu_2−xSe, alloys, and a (Cu,Pd)Se₂ solid solution. The selenide melt recedes to the Pd side of the system at 550 °C and its remnants persist at 400 °C. At the lower temperature, the gamut of Pd selenides becomes richer, and especially Pd₄Se and Pd₁₇Se₁₅ display significant solubility of Cu. The composition range of (Cu,Pd)Se₂ broadens and moves towards Cu-richer compositions as temperature decreases; CuSe and CuSe2 appear at 300 °C. The synthetic analogue of jaguéite, Cu₂Pd₃Se₄, is present at 400 °C and 300 °C, at Se concentrations above the Cu_2−xSe–Pd₁₇Se₁₅ line. At all examined temperatures, the individualized CuPd alloy dissolves Se, up to ~5 at% at low temperatures.