Effects of diffusion of Co/Ni cations of sol-gel derived ZrO2 polymorphic transformations

Abstract

Transition metal incorporated ZrO2 gel matrices have been prepared by impregnation method and investigated with FTIR/DTA/XRD. The metastable tetragonal - monoclinic - tetragonal - cubic phase transformations are revealed in the DTA heating process up to 1400°C for the studied gels. High-temperature tetragonal to monoclinic transition is also observed in the cooling process. It is found that the diffusing metal cations stabilize the low-temperature tetragonal phase. However, for high-temperature (900°C) calcined gels, both as-prepared and metal-stabilized tetragonal phases are reduced substantially. Correlations between metal diffusion and gel polymorphic stabilities are also demonstrated.