Ternary clathrates Ba-Cd-Ge: phase equilibria, crystal chemistry and physical properties

Abstract

The present paper describes the formation, phase relations at subsolidus temperatures and at 800 °C, crystal chemistry and physical properties of a series of ternary clathrates as part of the solid solution Ba8CdxGe43-5x/8[]3-3x/8, derived from binary Ba8Ge43[]3 with a solubility limit of 8 Cd per formula unit at 800 °C. Structural investigations in all cases confirm cubic primitive symmetry with a lattice parameter a~ 1.1 nm, consistent with the space group type P m3n . Both the temperature dependent x-ray spectra and the heat capacity define a low-lying, almost localized, phonon branch.