Synthesis and photoluminescent characteristics of Sr2CeO4 phosphors prepared via a microwave-assisted solvothermal process

Blue-light emitting Sr2CeO4 phosphors were successfully prepared via a microwave-assisted solvothermal method employing ethylene glycol as a solvent. The formation of Sr2CeO4 phase began when the solvothermally derived precursors were heated at 800 deg. C. With increase in heating temperatures, significantly enhanced excitation and emission intensities were observed because of an increase in the amount of Sr2CeO4. Heating at 1200 deg. C led to a substantial decrease in mission intensity due to thermal decomposition of Sr2CeO4 at elevated temperatures. The solvothermally derived Sr2CeO4 was found to exhibit higher emission intensity than the solid-state-reaction-derived phosphors. According to the deconvoluted emission spectra, two emission peaks are attributed to two metal-to-ligand charge-transfer states. Based on the deconvoluted results, a qualitative energy-level diagram of Sr2CeO4 was proposed. VUV-excited luminescence studies for Sr2CeO4 indicate that one peak at 193 nm is assigned to the charge-transfer transition between Sr2+ and O2-.