In-situ high-pressure behaviors of double-perovskite Sr₂ZnTeO₆

Structural and spectroscopic properties of Sr₂ZnTeO₆ (SZTO) were investigated by angle-dispersive synchrotron X-ray powder diffraction and Raman spectroscopy in a diamond anvil cell up to 31 GPa at room temperature. Although SZTO remained stable up to the highest pressure, the different pressure coefficients of the normalized axial compressibility were obtained as β_ab=8.16×10^-3 GPa^-1 and β_c=7.61×10^-3 GPa^-1. The bulk modulus B₀ was determined to be 190(1) GPa by fitting the pressure-volume data using the Birch-Murnaghan equation of state. All the observed Raman modes exhibited a broadening effect under high pressure. The vibrational band ϒ ₁ around 765 cm^-1, which is associated with the Te-O stretching mode in the basal plane of the TeO₆ octahedron, had the largest pressure coefficient, and the Grüneisen parameters for all the observed phonon modes also were calculated and presented. These parameters could be used to measure the amount of uniaxial or biaxial strain, providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains.