Color center of YAlO(3) with cation vacancies

High quality pure YAlO(3) crystal with dimension of [Phi] 30 x 50 mm(2) was grown by Czochralski technique. UV irradiation and air annealing bring additional absorption in the region 200-800 nm. The absorption spectra of perfect YAlO(3) and YAlO(3) containing cation vacancy (aluminium vacancy and yttrium vacancy) were calculated using density functional theory code CASTEP. Comparison of the simulated absorption spectra with the experimental absorption spectra of YAlO(3) after UV irradiation and air annealing treatments shows that cation vacancies are responsible for part of the coloration on YAlO(3) crystal.