The first-order Raman spectra and lattice dynamics for YAlO3 crystal

The phonon-dispersion curves of the YAlO3 crystal are calculated on the basis of a rigid-ion model using the measured frequency values by Raman and infrared polarized spectroscopy at room temperature. The temperature dependence of the molar heat capacity of YAlO3 is also calculated using the one-phonon density of states obtained from the phonon-dispersion curves. The first-order polarized Raman spectra of A(1g) mode in the YAlO3 crystal have been measured in the temperature range between 77 and 473 K. The temperature dependence for the linewidth of the A(1g) modes has been analyzed at 152, 350 and 550 cm(-1) using the phonon-dispersion curves, and the calculated result reproduces with the observed one in the temperature range of 77-500 K. Thus, the temperature dependence of linewidth of the A(1g) modes in YAlO3 crystal is approximately explained by the cubic anharmonic term in the expansion series of the crystal potential energy.