The effect of calcium concentration on the photoluminescence of CaTiO3: Pr3+ films prepared by the sol–gel method

Ca1−x + yPrxTiO3 (CPTO) films with x = 0.25 mol% and different y values were prepared by the sol–gel method. Both Ca excess and deficiency were found to be effective to improve the red emission brightness of the CPTO films, while they have small effect on the surface roughness and grain sizes of the films. The highest red emission at 612 nm for the case of Ca2+ deficiency happened on y = −x/2, and the one for the case of Ca2+ ions excess was on y = 3x. Charge compensation and substitution of Pr3+ for Ti4+ when Ca2+ ions was excessive in the CPTO films were proposed to explain the experimental results. These results indicate that the traditionally adopted Ca deficiencies may not be the best one for the efficient red emission of CPTO films, instead, a proper Ca excess is more effective.