A structure — mineralogical study of Ringwoodite

The powder XRD analysis of ringwoodite (γ-Fe2SiO4), which was synthesized in a II-stage anvil high — pressure capsule.was made. Its unit-cell parameter was calculated:a = 8.219 A. After the refinements, for several cycles, of the oxygen parameterx and the occupancy rate of Si in octahedron site, i.e., the iversion degreeu, the final result is R=0.077, when x = 0.379 A and u=27.5%, with the structural formula (Fe1.725Si0.275)VI (Si0.725Fe0.275)IVO4 and atomic distances (Fe, Si)VI-O = 2.022 A and (Si, Fe)VI-O = 1.836 A. Meanwhile, the Mossbauer spectroscopic analysis of the sample was conducted and the results obtained are in good agreement with those of X-ray structural analysis. This paper focuses on the phase transformation and the properties of bonds of α - Fe2 SiO4 →γ- Fe2 SiO4.