Ce doping induced trapping states and local electronic structure modifications in SrZnO2 nanophosphors

Abstract

This study presents Ce doping induced defect states in the SrZnO₂ system, probed through X-ray absorption spectroscopy, electronic spin resonance and thermoluminescence (TL) analysis. The local electronic structure at the Zn and Sr K-edge reveals distortion upon Ce incorporation in the SrZnO₂ system, whereas extended X-ray absorption fine structure analysis at the Ce L₃-edge shows an increase in Ce–O bond length with increasing Ce doping concentration, which indicates that Ce occupies Zn sites at low doping concentration and Sr sites at higher doping concentration. The previous investigations (Manju et al., Appl. Phys. Lett., 2021, 119, 121108) of this system indicated the presence of a mixed valence state of Ce in SrZnO₂, comprised of singly occupied 4f¹ and empty 4f⁰ states. Owing to the differences in valence state, Ce incorporation results in the formation of cation vacancies and oxygen interstitial defects in the system, and thereby the system exhibited a new feature in gamma irradiated TL glow curves. The variation in intensity of the doping induced feature in the glow curves is evidence of the variation in 4f⁰/4f¹ ratio of Ce energy levels. Hence, the combined analyses is comprehending the traits of the dopant and doping induced intrinsic defects, which will help in predicting the applicability of the material for lighting and scintillation devices.