Interconversion of perovskite and fluorite structures in Ce-Sc-O system.

CeScO(3) was synthesized by a two-step synthesis route involving a combustion method followed by vacuum heating at 1100 degrees C in the presence of Zr sponge which acts as an oxygen getter. The compound was characterized by various techniques such as X-ray diffraction (XRD), high temperature XRD, thermogravimetry, diffuse reflectance (DR)-UV visible spectrophotometry, and Raman spectroscopy. Fluorite-type (F-type) solid solution with composition Ce(0.5)Sc(0.5)O(1.75) was observed as an intermediate during the synthesis of CeScO(3). Only by mere redox reaction was a reversible transformation between fluorite-type structure and perovskites structure observed. CeScO(3) was found as semiconducting oxide with band gap of 3.2 eV arising mainly between O p states in the valence band and Sc d and Ce d states in the conduction band with small contributions coming from Ce f and Sc p states. First-principles potential plane-wave-based calculations were performed for the band gap and its origin in CeScO(3). Photoluminescence measurement showed that CeScO(3) is a potential host material giving broad blue emission. This was further confirmed by demonstrating CeScO(3) doped with 2 mol % Tb(3+) compound as an efficient green light emitter.