MICROSTRUCTURAL AND MECHANICAL EFFECTS OF OXIDE ADDITION INTO THIN ZRO2 MATRIX

Zirconia was stabilized in thin film form by three ceramic oxides (MgO , CeO2, Gd2O3). Crystallographic and microstructural feature studies w ere undertaken. X-ray diffraction analysis allowed the stabilization p rocess to be followed as a function of dopant concentration in the ZrO 2 matrix. It was found that for the three systems of interest, the mol e percentage of additive oxide needed to stabilize zirconia in a cubic lattice is in agreement with the equilibrium phase diagrams, i.e. mor e than 14 mol% for MgO, 18 mol% for CeO2 and 10 mol% for Gd2O3. Based on X-ray diffraction measurements, a series of mixed films in ZrO2-MgO , ZrO2-CeO2 and ZrO2-Gd2O3 produced by co-evaporation at 550 degrees C was studied in order to determine the effect of dopant concentration on lattice parameters, average particle size and residual stress. A cu bic lattice parameter in the ZrO2-MgO system was found to decrease slo wly with increasing MgO mole percentage whilst it increases linearly f or the ZrO2-CeO2 and ZrO2-Gd2O3 systems. Particle size was found to be lower than 200 Angstrom for the samples investigated but films were c rystalline. A merely indicative stress study in stabilized samples sho ws tensile stresses in the ZrO2-MgO system. Residual stresses were hig hly compressive in the two other systems.