Large enhancement of photoluminescence in SrTiO3:Pr powders by fluorhydric acid treatment

We have investigated the effect of fluorhydric acid (HF) treatment on the photoluminescence (PL) properties of SrTiO₃:Pr³⁺ powders prepared by sol-gel method. The red emission intensity increased significantly up to 18 times when the powders were subjected into a water-diluted 5% HF solution for 10 min. The origin of the PL enhancement was ascribed to the increase of oxygen vacancies in HF-treated SrTiO₃:Pr³⁺ powders. This study also manifested that HF etching is more effective to improve the red PL intensity than vacuum-annealing for the sol-gel made SrTiO₃:Pr³⁺ powders.