A novel route to prepare Zn2GeO4 with a spinel cubic structure

This study successfully implements a novel, practical, and economical synthetic route to prepare the cubic phase of Zn 2 GeO 4 by ball-milling polycrystalline Zn 2 GeO 4 particles with the hexagonal phase. These were previously synthesized via the well-known Pechini method. Topographical and Chemical analyses of the samples showed particles with random shape and homogeneous chemical composition with high purity. The crystallographic characterization of samples clearly revealed a phase transformation of their particles from hexagonal to spinel structure. The mechanochemical treatment resulted in reducing the particle size from 72 nm to 23 nm. Also, both phases have a semiconductor nature with a direct band gap energy 4.4 eV and 4.05 eV for hexagonal and cubic phases, respectively. Besides, the theoretical calculations confirm the feasibility of phase transformation based on their tiny energy difference of 70 meV per formula unit between hexagonal and cubic phases, which is provided by ball-milling. Our findings demonstrate a facile route to synthesize the metastable cubic phase of the Zn 2 GeO 4 .