The Se2 (Gas) Fugacity in Systems with Noble Metals: Chrisstanleyite Ag2Pd3Se4 – Naumannite Ag2Se–β-PdSe2 and Luberoite Pt5Se4–Sudovikovite PtSe2

Аннотация

The reactions of 6Ag_(cr) + 3PdSe_2(cr) = 2Ag₂Se_(cr) + Ag₂Pd₃Se_4(cr) and 12Ag_(cr) + 5PtSe_2(cr) = 6Ag₂Se_(cr) + Pt₅Se_4(cr) were studied with the EMF method in a completely solid-state galvanic cell with an Ag ion-conducting solid electrolyte with overall gas space (argon under atmospheric pressure). The EMF vs. temperature dependencies were obtained in the temperature ranges of Т = 425–648 K and 501–713 K, respectively. Then, they were recalculated for gaseous Se fugacity in dependence on the temperature for nonvariant equilibriums of Ag₂Pd₃Se₄ (chrisstanleyite)–β-PdSe₂ (the phase, which transforms into verbeekite under low temperatures)–Ag₂Se (naumannite) and Pt₅Se₄ (luberoite)–PtSe₂ (sudovikovite): logf Se₂(gas) (Ag₂Pd₃Se₄/Ag₂Se/PdSe₂) = 7.710 ± 0.050 – 8.524 ± 0.026(1000/T), logfSe₂(gas) (Pt₅Se₄/PtSe₂) = 7.135 ± 0.027 – 12.274 ± 0.016(1000/T).