Liquidus projection of the Ag–Ba–Ge system and melting points of clathrate type-I compounds

Abstract

The liquidus and solidus projection has been constructed for the Ag–Ba–Ge system up to 33.3at% Ba, using electron micro probe analysis (EPMA), X-ray powder diffraction (XRD) and differential thermal analysis (DSC/DTA). Eight different primary crystallization regions were found: (Ge), Ba8AgxGe46−x−y□y (κI) (□ is a vacancy), Ba6AgxGe25−x (κIx), BaGe2, Ba(Ag1−xGex)2 (τ1), BaAg2−xGe2+x (τ2) BaAg5 and (Ag). The ternary invariant reactions have been determined for the region investigated and are the basis for a Schulz–Scheil diagram.The second part of this work provides a comprehensive compilation of melting points of ternary A8TxM46−x and quaternary (A=Sr, Ba, Eu; T=Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga; M=Si, Ge, Sn) clathrate type-I compounds and decomposition temperatures of inverse clathrate type-I Ge38{P,As,Sb}8{Cl,Br,I}8, Si46−xPxTey and tin based compounds.