Synthesis and structural properties of type I potassium SiGe alloy clathrates

•Synthesis of three new alloyed type I SiGe alloy clathrates with potassium as guest.•Alloying demonstrated for wide SiGe composition range.•Synthesis techniques results in high yield.

We report on the synthesis and structural characterization of type I SiGe alloy clathrates, with potassium as the guest species, synthesized by thermal decomposition and kinetically controlled thermal decomposition from K4(Si1−xGex)4 precursor phases with x=0.1, 0.3, and 0.75. The K8(Si1−xGex)46 clathrates were structurally characterized by X-ray diffraction. Rietveld refinement on the XRD data indicated that Ge preferentially occupies the 24k and 6c sites for x<0.5 but preferentially occupies the 16i and 24k sites for x>0.5.