Synthesis and microstructure of Gd2O3-doped HfO2 ceramics

Abstract The effect of Gd 2 O 3 -doping on the crystal structure, surface morphology and chemical composition of the Gd 2 O 3 –HfO 2 system is reported. Gd 2 O 3 –HfO 2 ceramics with variable composition were prepared by varying the Gd 2 O 3 composition in the range of 0–38 mol% balanced HfO 2 . X-ray diffraction (XRD) analysis indicates that the Gd 2 O 3 concentration influences the crystal structure of the Gd 2 O 3 –HfO 2 ceramics. Pure HfO 2 and Gd 2 O 3 crystallize in monoclinic and body centered cubic structure, respectively. The Gd 2 O 3 –HfO 2 ceramics exhibit mixed monoclinic and fluorite structure when the Gd 2 O 3 concentration is varied from 4 to 12 mol%. At 20 mol% of Gd 2 O 3 , existence of only the fluorite phase was found. Increasing the Gd 2 O 3 concentration to 38 mol% results in the formation of single-phase pyrochlore Gd 2 Hf 2 O 7 ( a = 5.258 A).