2018/01/24 by Xuerui Cheng, Jie Yuan, Xiang Zhu +3
Materials Science · Engineering · #Thermal Expansion and Ionic Conductivity #Microwave Dielectric Ceramics Synthesis #Ferroelectric and Piezoelectric Materials
paper · doi:10.1088/1361-6463/aaaa3d
Abstract Zn 2 GeO 4 , as an open-framework structure compound, exhibits negative thermal expansion (NTE) below room temperature. In this work, we investigated the structural stability and phonon modes employing the x-ray diffraction and Raman spectroscopy under high pressure up to 23.0 GPa within a diamond anvil cell, and we observed that a pressure-induced irreversible amorphization took place around 10.1 GPa. Bulk modulus, pressure coefficients, and Grüneisen parameters were measured for the initial rhombohedral structure. Several low-frequency rigid-unit modes are found to have negative Grüneisen parameter, which accounts for the primary part of NTE in Zn 2 GeO 4 . These results further confirm the hypothesis that the pressure-induced amorphization and the negative thermal expansion are correlated phenomena.