Observation of anomalous phase transition and band gap shrinkage in zinc germanate nanorods

This work reports the high temperature anomalous phase transition with high dielectric constant and low band gap in pure zinc germanate (Zn2GeO4) nanorods. Crystal structure of Zn2GeO4 nanorods were analyzed by X-ray powder diffraction and Raman studies. Electron microscopy reveals that nanorods have average diameter and length of 30 nm and 100 nm, respectively. UV-ViS study indicates low band gap of 3.96 eV. The observed dielectric constant is 40 times higher than bulk Zn2GeO4. High dielectric constant of similar to 772 and phase transition was observed around 400 degrees C. In the low and high temperature range, activation energy were similar to 0.33 and 1.34 eV. High dielectric constant and shrinkage in bang gap with temperature phase transition of Zn2GeO4 nanorods makes it the potential candidate for nano-optoelectronic and nanodevices applications in near future.