Thermal expansion and compressibility of calcium scandate CaSc2O4

Abstract

By using in-situ synchrotron angle-dispersive X-ray diffraction measurements, the thermal expansion and compressibility of orthorhombic CaSc2O4 were investigated up to 1173 K at ambient pressure and up to 15.9 GPa at room temperature, respectively. No phase transformation was observed in this study. The thermal expansion coefficients of CaSc2O4 were determined to be 4.17(3) × 10−5 K−1, 1.60(1) × 10−5 K−1, 1.18(1) × 10−5 K−1 and 1.39(1) × 10−5 K−1 for the V, a-, b- and c-axis, respectively. The isothermal bulk modulus of CaSc2O4 was obtained as 153.8(50) GPa with its first pressure derivative of 6.5(9). The axial compressibility was estimated to be 123(3), 177(4) and 242(11) GPa for the a-, b- and c-axis, respectively. Both the thermal expansion and compressibility of CaSc2O4 show axial anisotropy. The heat capacities (Cv and Cp) of CaSc2O4 was estimated by using a Kieffer model with Raman spectroscopy data and present experimental results. The standard entropy (S2980) and Debye temperature (θD) of CaSc2O4 were also calculated.