Composition, lattice parameters, and room temperature elastic constants of natural single crystal xenotime from Novo Horizonte

Abstract

The composition, lattice parameters, and elastic constants of natural single crystal YPO4 xenotime from Novo Horizonte (Brazil) were determined using EPMA, XRD, and the pulse-echo technique. The composition indicates a 24% substitution of Y sites with other rare-earth elements. The lattice parameters of the studied crystal deviated only slightly from those reported for synthetic YPO4 and were in a good agreement with trends obeyed by other orthophosphates with the xenotime structure. The measured elastic constants C 11, C 33, C 44, and C 66 were consistent with synthetic crystals when porosity was accounted for. C 12 and C 13 constants were evaluated based on the comparison with other materials with xenotime structure. The elastic constants could be rationalized using interionic force constants and bond energies.