Synthesis of sub-micron spherical monoclinic stabilized Al/zirconia, Al–Ni/zirconia and Al–Ni–Cu/zirconia solid solutions

A series of monodisperse sub-micron spherical zirconia solid solutions were prepared by hydrolysis of zirconium, aluminum, nickel and copper salts in ethanol. The heat-treatment process of the as-prepared amorphous materials in air atmosphere at 500 °C leaded to the production of the zirconia solid solutions in tetragonal phase. Further heating from 800–1400 °C resulted in the formation of stabilized monoclinic zirconia solid solutions. X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the formation of pure phase nanocrystalline zirconia solid solutions with spherical shape even at 1000 °C. Optical studies of the nanostructured solid solutions showed the decreases in band gaps with increasing the heat-treatment temperature due to grain growth.