THE EFFECT OF THE CHOICE OF THE STARTING MATERIAL ON THE PHASE COMPOSITION AND PHASE STABILITY OF ZRO2 PARTICLES SYNTHESIZED BY THE HYDROTHERMAL METHOD

In this work, the phase composition, microstructure and phase stability of zirconium dioxide samples obtained by hydrothermal synthesis from various starting materials were investigated. It was found that when using ZrOCl2·8H2O as a starting material, zirconium dioxide particles containing monoclinic and tetragonal (cubic) phases are formed, at the same time, when using ZrO(NO3)2·2H2O as a starting material, only the monoclinic phase was identified in the samples. The CSR dimensions calculated using the Scherrer equation are in the range from 9 to 40 nm. Analysis of SEM images of experimental samples showed that nanoparticles form conglomerates with sizes of several microns. A study of the phase stability of the t, c – ZrO2 phase from temperature exposure showed that t, c – ZrO2 is a metastable phase with CSR sizes up to annealing of 10 nm. With an increase in the annealing temperature, the metastable tetragonal (cubic) phase of ZrO2 gradually transforms into a monoclinic one, due to the processes of minimizing surface energy and particle proliferation, as well as sintering conglomerates into larger monolithic particles.