The study of multi-phase rare-earth phosphate-borosilicate glass composites synthesized by the ceramic method via a 1-step pathway

Abstract

Multi-phase glass-ceramic composites (i.e., composite materials containing multiple ceramic crystallites dispersed in a glass matrix) that have applications as potential nuclear waste form materials have been synthesized and examined. Crystallites of xenotime-type (YPO₄) phosphates and monazite-type (LaPO₄) phosphates were dispersed in borosilicate glass. The composition of the glass matrix was varied to eliminate the formation of unwanted secondary phases. Powder X-ray diffraction (XRD), X-ray absorption near-edge spectroscopy (XANES), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray spectroscopy (EDX) were employed to investigate the long-range order, local chemical environment, and morphology of the composite materials. The XRD patterns and XANES spectra revealed the exclusive presence of LaPO₄ and YPO₄ phases within the composite subsequent to the modification of the glass matrix. The SEM images and EDX maps collected from these composite materials also showed only the presence of LaPO₄ and YPO₄ after modification of the glass composition by removing Na₂O and CaO.