Synthesis and microstructure of Gd2O3-doped HfO2 ceramics

The effect of Gd2O3-doping on the crystal structure, surface morphology and chemical composition of the Gd2O3-HfO2 system is reported. Gd2O3-HfO2 ceramics with variable composition were prepared by varying the Gd2O3 composition in the range of 0-38 mol% balanced Hfa(2). X-ray diffraction (XRD) analysis indicates that the Gd2O3 concentration influences the crystal structure of the Gd2O3-HfO2 ceramics. Pure HfO2 and Gd2O3 crystallize in monoclinic and body centered cubic structure, respectively. The Gd2O3-HfO2 ceramics exhibit mixed monoclinic and fluorite structure when the Gd2O3 concentration is varied from 4 to 12 mol%. At 20 mol% of Gd2O3, existence of only the fluorite phase was found. Increasing the Gd2O3 concentration to 38 mol% results in the formation of single-phase pyrochlore Gd2Hf2O7 (a = 5.258 angstrom). (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.