RAMAN-STUDY OF PHASE-TRANSITIONS IN PURE AND ALLOYED ZIRCONIA INDUCEDBY BALL-MILLING AND A LASER-BEAM

High-temperature phases of ZrO2 were obtained at room temperature by i ncorporating a few mole fractions of other oxides (MgO, Y2O3 or CoO) i n a zirconia crystal lattice using high-energy ball-milling. Raman spe ctra obtained after an adequate period of ball-milling show the format ion of ZrO2-MgO and ZrO2-Y2O3 cubic solid solutions and a ZrO2-CoO tet ragonal solid solution. However, in the case of pure monoclinic zircon ia, the transformation from a monoclinic to a tetragonal structure cou ld not be completed by the use of ball-milling only. The spectra of fu lly stabilized solid solutions did not change essentially with laser p ower, 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.