Properties of t-zirconia prepared by a composite-assisted nonhydrolytic sol-gel

High surface area and highly crystalline tetragonal Ni-Si-doped ZrO₂ samples were prepared using a nonhydrolytic sol-gel method. The synthesis involved the condensation of zirconium chloride and isopropyl ether in the presence of a chitosan-based composites containing Ni and Si (Ni@Si-CS), followed by calcination to remove the CS. The interactions between the zirconium precursor and the Ni@Si-CS composites were studied and correlated with the effect on morphologies, crystalline structure, phase compositions, and surface area. These parameters were evaluated for different Ni@Si-CS to ZrO₂ mass ratios. It was found that increasing the concentration of Ni@Si-CS composite led to smaller grains of ZrO₂ nanocrystals and an overall material with a higher surface area. The stability of the tetragonal/cubic phases following calcination at 800°C was correlated with the presence of low amounts of Ni²⁺ in the sublattice of ZrO₂ and the presence of the Si-chitosan, which acted as steric stabilizer.