FORMATION AND PROPERTIES OF CoTiO₃ CERAMICS WITH THE INTRODUCTION OF OXIDE STABILIZING ADDITIVES

A comprehensive study was carried out to investigate the influence of the type of cobalt-containing component and stabilizing oxide additives on the phase composition, microstructure, and mechanical properties of cobalt titanate-based ceramics synthesized by mechanochemical solid-state processing. Cobalt nitrate, cobalt sulfate, and cobalt chloride were used as cobalt-containing precursors and mixed with titanium dioxide in equimolar ratios, followed by mechanochemical milling and thermal sintering at 1000 °C. X-ray diffraction and scanning electron microscopy revealed that a two-phase CoTiO₃ -TiO₂ (rutile) system is formed in all samples, while the phase ratio and microstructural features strongly depend on the type of the initial cobalt-containing component. The use of cobalt chloride was shown to increase the weight fraction of the CoTiO₃ phase up to ~60 wt.% and to promote the formation of a denser and more homogeneous microstructure compared with ceramics synthesized using cobalt nitrate and cobalt sulfate, in which the rutile phase dominates. It was established that the introduction of stabilizing oxide additives ZrO₂ , MgO, and Y₂ O₃ suppresses grain growth and increases the density of interphase boundaries. The addition of yttrium oxide is accompanied by the formation of a secondary Y₂ Ti₂ O₇ phase and provides the most pronounced structural strengthening effect. The maximum microhardness value (742 ± 14 HV) was achieved for Y₂ O₃ -modified samples. The obtained results demonstrate that a targeted selection of the cobalt-containing components and stabilizing oxide additives enables effective control over the phase composition, microstructure, and mechanical properties of CoTiO₃ -ceramics synthesized by the mechanochemical method.

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