Probing the effect of radiation damage on the structure of rare-earth phosphates

Synthetic analogues of naturally occurring monazite (REPO4; RE = La to Gd) and xenotime (RE′PO4; RE′ = Tb to Lu and Y) minerals have been identified as potential wasteforms for nuclear waste. High energy ion-implantation of crystalline materials simulates radiation-induced structural damage and allows for the radiation resistance of a crystal structure to be probed. The structural stability of Au− ion-implanted La1-xYbxPO4 materials was investigated using micro-X-ray diffraction (μ-XRD) and glancing angle X-ray absorption near-edge spectroscopy (GA-XANES) in this study. The long- and short-range order of La1-xYbxPO4 (x = 0, 0.3, 0.7, 1.0) is affected by ion-implantation and, thus, the materials are prone to structural damage. The structures of some members of the La1-xYbxPO4 series (x = 0.7 and 1.0) were observed to partially recover after being implanted with Au− ions to a high dose. The structures of all members of the La1-xYbxPO4 series were observed to recover from damage resulting from ion-implantation after annealing the materials at temperatures ≥300 °C. [Display omitted] •Structural stability of La1-xYbxPO4 was studied using glancing angle XANES.•Loss of short- and long-range order in La1-xYbxPO4 due to ion-implantation observed.•High dose of Au− ions induced partial recrystallization of YbPO4 and La0.3Yb0.7PO4.•Glancing angle XANES spectra were sensitive to changes in the structure.•Annealing was found to result in the recrystallization of the damaged structure.