Raman scattering and x-ray diffraction studies of polycrystalline CaCu3Ti4O12 under high-pressure

Abstract

We report Raman scattering and x-ray diffraction studies of polycrystalline CaCu3Ti4O12 (CCTO) under high pressures. The pressure dependence of several Raman modes was investigated. No anomalies have been observed on the phonon spectra thereby indicating that the Th sIm 3¯d structure remains stable up to the maximum pressure s5.3 GPad we reached in this experiment. The pressure coefficients for the observed Raman modes were determined. This set of parameters was used for evaluating the stress developed in CCTO thin films. The high-pressure x-ray studies were extended up to 46 GPa and the data confirmed that the Th structure remains stable up to this pressure. The pressure-volume data are well described by the Birch’s equation of state. The experimental value of the zero pressure bulk modulus is B0=212±2 GPa. Grüneisen parameters of CCTO were also determined.