Synthesis of Multiphase Rare-Earth Phosphate Borosilicate Glass-Ceramic Composite Materials Using a One-Step Coprecipitation Method

Composite materials consisting of multiple ceramic crystallites dispersed within a glass matrix were synthesized using the coprecipitation method. The coprecipitation technique enhances mixing of the precursors, leading to a decrease in the diffusion distance of the ions. Multiphase composites are expected to sequester substantial amounts of different nuclear waste elements when used as a nuclear waste form. The crystalline phases can incorporate substantial quantities of actinides based on the crystal structures of the crystalline phases, while glasses can accommodate significant amounts of small fission products such as Cs, Xe, Sr, etc. YPO4 and LaPO4 were dispersed in a borosilicate glass (BG) matrix. Modifications were made to the composition of the glass matrix to prevent the formation of undesired secondary phases. Powder X-ray diffraction (XRD), X-ray absorption near-edge spectroscopy (XANES), and scanning electron microscopy (SEM) were used to study the long-range order, the local chemical environment, and the morphology of the synthesized materials. Analysis of the X-ray diffraction (XRD) patterns indicated the presence of just the LaPO4 and YPO4 phases in the composite material following modification of the glass matrix, thus confirming that only these two crystalline phases were present in this composite material, which was further confirmed by XANES and SEM analyses.