Low-temperature metastable tetragonal zirconia nanoparticles (NpMTZ) synthesized from local zircon by a modified sodium carbonate sintering method

The metastable tetragonal zirconia is an interesting material exhibiting a high surface area and photoluminescence properties. The present work studies the characteristics of the metastable tetragonal zirconia nanoparticles that were successfully prepared from local zircon without using a template by a modified sodium carbonate sintering method, followed by leaching, slow hydrolysis, and calcination at a low temperature. Zircon and alkaline were combined at a mole ratio of 1:2 and sintered at 1000 °C. The sintered material was washed with water to dissolve the silica and followed by leaching with sulfuric acid at pH 1–2 to dissolve the zirconia then followed by slow hydrolysis until pH 9 to precipitate zirconium hydroxide. The final product was evaluated including thermal behavior, phase transformation, chemical composition, infrared spectra, microstructure, and textural properties. Crystallization of zirconia occurred at 564.29 °C. Good crystallinity of the zirconia phase was obtained at 800 °C consisting of 80% tetragonal zirconia with a crystal size of 11 nm corresponding to its crystal plane of (101) and 20% monoclinic zirconia. At this temperature, zirconia attains 83.19% in purity, shows typical infrared spectrum, and consists of particles less than 40 nm in sizes that agglomerate, belongs to a mesoporous material exhibiting a high surface area of 46.990 m2/g. Increase in calcination temperature at 1050 °C transformed the tetragonal phase to the monoclinic phase of zirconia. Overall, the present work reveals a promising template-free method on the preparation of the metastable tetragonal zirconia nanoparticles from local zircon.