An Unexpected Cubic Symmetry in Group IV Alloys Prepared Using Pressure and Temperature

Abstract

The cubic diamond (Fd3m) group IVAe lement Si has been the material driver of the electronics industry since its inception. We report synthesis of an ew cubic (Im3m) group IVAmaterial, aGeSn solid solution, upon heating Ge and Sn at pressures from 13 to 28 GPausing double-sided diamond anvil laser-heating and large volume press methods.B oth methods were coupled with in situ angle dispersive X-ray diffraction characterization. The new material substantially enriches the seminal group IVAalloymaterials landscape by introducing an eightfold coordinated cubic symmetry,w hichm arkedly expands on the conventional tetrahedrally coordinated cubic one. This cubic solid solution is formed, despite Ge never adopting the Im3ms ymmetry,m elting inhibiting subsequent Im3m formation and reactant Ge and Sn having unlike crystal structures and atomic radii at all these pressures.This is hence achieved without adherence to conventional formation criteria and routes to synthesis.This advance creates fertile avenues for new materials development.