Interconversion of perovskite and fluorite structures in Ce−Sc−O system

Abstract

CeScO₃ was synthesized by a two-step synthesis route involving a combustion method followed by vacuum heating at 1100 °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_0.5Sc_0.5O_1.75 was observed as an intermediate during the synthesis of CeScO₃. Only by mere redox reaction was a reversible transformation between fluorite-type structure and perovskites structure observed. CeScO₃ 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 CeScO₃. Photoluminescence measurement showed that CeScO₃ is a potential host material giving broad blue emission. This was further confirmed by demonstrating CeScO₃ doped with 2 mol % Tb³⁺ compound as an efficient green light emitter.