Assessment of free volume using positron annihilation study in Ag2O-doped ZnO-P2O5-SeO2 glass ceramics

Abstract

Glass ceramics with the composition ZnO–P₂O₅–SeO₂ doped with varying amounts of silver oxide (Ag₂O) were synthesized. The effect of Ag₂O on atomic vacancy formation was studied using positron annihilation lifetime spectroscopy (PALS). XRD and SEM studies confirmed the presence of Ag₃PO₄, Ag₂SeO₃ crystal phases, and Ag⁰ nanoparticles in the glassy matrix. Infrared spectroscopy showed that increasing Ag₂O content enhanced the fraction of Ag⁰ nanoparticles in the glass network while decreasing the fraction of ZnO₄ and [SeO₄]²⁻ units. This change indicated an increase in free volume defects, such as voids, that trap positrons. Analysis of positron annihilation lifetime spectra revealed an increase in the longest-lived component (I₃) and its lifetime (τ₃) with higher Ag₂O concentrations, indicating greater void expansion and agglomeration in the glass ceramic. These findings correspond to changes in ac conductivity and suggested that these glass ceramics could be developed as solid electrolytes for solid-state batteries.