Structural properties of the fluorite- and pyrochlore-type compounds in the Gd2O3–ZrO2 system xGdO1.5–(1−x)ZrO2 with 0.18≤x≤0.62

Structural properties of the Gd2O3–ZrO2 system, xGdO1.5–(1−x)ZrO2 with 0.18≤x≤0.62, were investigated by 155Gd Mössbauer spectroscopy and powder X-ray diffraction. The results indicated that local arrangements around the Gd3+ ions are similar in the fluorite (F)- and pyrochlore (P)-type compounds for 0.18≤x≤0.50, whereas they vary slightly for 0.50<x≤0.62. Displacements of the six oxygen ions in the 48f site from the ideal position of the related F-type compound increase with increasing x for 0.18≤x≤0.50 and decrease slightly for 0.50<x≤0.62. The displacement is the largest in the stoichiometric P-type Gd2Zr2O7 (x=0.50).