Mechanical characteristics, structure, and phase stability of tetragonal crystals of ZrO2–Y2O3 solid solutions doped with cerium and neodymium oxides

Abstract

The phase composition, structure, and mechanical characteristics of ZrO2-based crystals stabilized with yttrium, cerium, and/or neodymium oxides at a total concentration of 2.8 mol% were studied. The stability of the phase composition and the mechanical characteristics of the crystals after annealing in air are considered. The entry of Nd3+ cations into the transformable (t) and nontransformable (t′) tetragonal phases was studied by optical spectroscopy. It was found that partial replacement of Y2O3 with CeO2 or Nd2O3 in ZrO2-based solid solutions results in crystals with high microhardness (~1200 MPa) and high fracture toughness (~12–15 MPa m1/2). Annealing in air at 1200°С leads to a change in the phase composition and a decrease in the crack resistance in (ZrO2)0.972(Y2O3)0.02(СeO2)0.008 crystals. The co-doping of the crystals with CeO2 and Nd2O3 and the predominant arrangement of Nd3+ ions in the t phase prevent the appearance of a monoclinic phase in the bulk of the material and result in high fracture toughness of (ZrO2)0.972(Y2O3)0.02(CeO2)0.004(Nd2O3)0.004 crystals after annealing.