A Study on the High Temperature-High Pressure Stability and the X-Ray Phase Analysis for Compounds R2Fe4/3W2/3O7 with Pyrochlore Structure

The compounds R2Fe4/3W2/3O7 (R=Er, Yb, Dy) treated with high temperature-high pressure have been studied by X-ray diffraction and PSPC. It is found that under the condition of 3.7 GPa and 1 200 ℃, the compounds with hexagonal pyrochlore structure synthesized under atmospheric pressure and high temperature and decompose into a polyphase compound system (R2WO6, RFeO3, WO3 and Fe2O3). It is also found that under the condition of same high temperature but high pressure, the mixture of R2O3, Fe2O3 and WO3 composed to same polyphase compound system too. The stable zone of compound R2Fe4/3W2/3O7 under high pressure is described in this paper.