Raman study of phase transitions in pure and alloyed zirconia induced by ball-milling and a laser beam

High-temperature phases of ZrO2 were obtained at room temperature by incorporating a few mole fractions of other oxides (MgO, Y2O3 or CoO) in a zirconia crystal lattice using high-energy ball-milling. Raman spectra obtained after an adequate period of ball-milling show the formation of ZrO2-MgO and ZrO2-Y2O3 cubic solid solutions and a ZrO2-CoO tetragonal solid solution. However, in the case of pure monoclinic zirconia, the transformation from a monoclinic to a tetragonal structure could not be completed by the use of ball-milling only. The spectra of fully stabilized solid solutions did not change essentially with laser power, while insufficiently milled samples underwent phase changes when the laser power increased. In pure milled zirconia, annealing effects were observed. (C) 1997 Elsevier Science B.V.