Melt grown ZrO2 single crystals partially stabilized with Gd2O3: phase composition and indentation induced transformations

Abstract ZrO2 solid solution crystals partially stabilized with Gd2O3 in the 2.0 to 4.0 mol% concentration range have been grown using the directional melt crystallization in a cold crucible. We show that the crystals have a homogeneous distribution of the components along the length of the crystal, and their chemical composition corresponds to that of the initial charge. The phase composition of the crystals has been studied using X-ray diffraction. The local phase composition in the vicinity of the indentation has been studied using Raman spectroscopy. The microhardness and fracture toughness of the crystals have been studied by indentation. The correlation between the fracture toughness of the crystals and their phase composition and indentation induced transformations has been discussed. We show that an increase in the Gd2O3 concentration in the crystals from 2.8 to 4.0 mol% reduces the content of the transformable tetragonal t phase, its tetragonality degree and the intensity of the indentation induced tetragonal to monoclinic phase transition. These factors are known to eventually reduce the fracture toughness of the crystals with an increase in the Gd2O3 concentration.