Phase formation and crystal structure determination in the Y2O3–TeO2 system prepared in an oxygen atmosphere

The solid state synthesis of phases in the Y2O3–TeO2 system under oxygen atmosphere is presented here as a method of obtaining pure material starting from simple oxides such as Y2O3 and α-TeO2. In the composition range of 0–100% of TeO2, the compounds Y6TeO12, Y2TeO6, Y2Te4O11, Y2Te5O13 and Y2Te6O15 were synthesized after annealing at 770–1100 °C. The reactions of decomposition of the phases at higher temperatures are also reported.The crystal structure of Y6TeO12 has been refined by the Rietveld method from X-ray powder diffraction data. It crystallizes with the rhombohedral space group R-3 (S.G. no. 148) as the homologous compound In6TeO12. It is based on a three dimensional arrangement of isolated TeO6 octahedra (TeO = 1.94 Å) and edge-shared YO7 polyhedra (YO bond lengths ranging from 2.18 to 2.65 Å).