Diffraction analysis of metamict samarskite

摘要: Samarskite, a chemically complex Nb,Ta oxide with high contents of U and Th has been considered X-ray amorphous. So far, detailed structural information deduced from crystallized reaction products after the mineral undergone heat treatment up to 1000/sup 0/C. In this study, untreated (neither thermal nor physical) samarskite Mitchell County, N.C. composition approximated by AB/sub 2/O/sub 6/ where A ions are Y, rare earths B Nb, Ta Fe, investigated large diffraction using AgK..cap alpha.. as radiation probe. From observed data, total scattered intensity per atom I/sub a/(K) was determined Fourier transformed, obtain radial distribution function (RDF), which revealed closest metal-oxygen distances (r/sub A-O/ = 2.4 angstrom r/sub B-O/ 2.0 angstrom). The area under first peak corresponds 3.6 +/- 1 atoms, indicates that sum oxygen about an B-type ion lies between 11 12 atoms. RDF metamict appears be typical for short range order found in truly amorphous solids.