Synthesis of a mixed-rare-earth aluminum garnet solid solution

In this work, the substitution of commercial Y2O3 by a rare earth mixed oxide, RE2O3, to form yttrium aluminum garnet (Y3Al5O12-YAG), was investigated. Al2O3:Y2O3 and Al2O3:RE2O3 powder mixtures were milled and pressed. Compacts were sintered at 1000, 1400 or 1600 degrees C, for 120 min. RE2O3 oxide was characterized by high-resolution X-ray diffraction (HRXRD) and compared to Y2O3. X-ray diffraction pattern of the RE2O3 indicates a true solid solution formation. Rietveld refinement of the sintered YAG and (RE)AG revealed a similar crystal structure. Microstructural analysis of both, YAG or (RE)AG, revealed similar grain sizes of about 2.5 mu m and mechanical properties, with hardness of 400 HV and fracture toughness of 3.8 MPam(1/2). It could be, thus, demonstrated that pure Y2O3 can be substituted by the rare-earth solid solution, RE2O3, in the formation of YAGs, presenting similar microstructures and mechanical properties. (C) 2012 Elsevier B.V. All rights reserved.