Kazan National Research Technological University, Kazan, Russia:

E. V. Petrova, Professor at the Department of Analytical Chemistry, Certification and Quality Management, Doctor of Chemical Sciences, Associate Professor, e-mail: katrin-vv@mail.ru
A. F. Dresvyannikov, Head of the Department of Electrochemical Technology, Doctor of Chemical Sciences, Professor
A. I. Khayrullina, Assistant Lecturer, Department of Electrochemical Technology
L. I. Kashfrazyeva, Postgraduate Student, Department of Analytical Chemistry, Certification and Quality Management

This paper focuses on the development of solutions to find methods that would enable to obtain complex oxide systems of Al₂O₃ – ZrO₂ – Me_xO_y (Me = Mg, La) with aluminium using electrogenerated reagents in a special hydrodynamic mode of an undivided coaxial cell with a great difference in the electrode area. With the help of electron microscopy, X-ray phase analysis and laser diffraction, the morphology and phase composition of the oxide systems Al₂O₃ – ZrO₂ – Me_xO_y were studied. The authors also looked at the processes involved in the formation of precursors of complex aluminium and zirconium oxide systems in the environment of electrogenerated
reagents being rapidly stirred (which is possible in an undivided coaxial cell) and amid phase transformations of the products. It is demonstrated that the particle morphology of aluminium oxide doped with zirconium, magnesium and lanthanum oxides is governed by the production environment. The average size of such particles is 20–80 nm. The authors established the environment in which the complex hydroxide of Mg₇Al₄(OН)₂₂ is formed. This hydroxide produces an Al₂MgO₄ spinel, which serves to stabilize α-Al₂O₃ and the tetragonal zirconium oxide t-ZrO₂. The latter maintains stability in a broad temperature range in the complex oxide system of Al₂O₃ – ZrO₂ – MgO. Through experiment it was proved that the introduction of La³⁺ in the Al₂O₃ – ZrO₂ – MgO system by adding cations of La (III) in the electrolyte and through soluble aluminium anode electrolysis would result in cubic and tetragonal phases of zirconium oxide forming in the heat treated product, as well as lanthanum aluminate forming in it. The established regularities can help predict the effect of the process environment on the particle size and morphology, the phase and chemical compositions of the Al₂O₃ – ZrO₂ – MexOy, oxide systems, and, consequently, on the physical and chemical properties of the latter.
This research study was carried out using the facilities of the Shared Knowledge Centre for Nanomaterials & Nanotechnologies under the governmental assignment of the Ministry of Education and Science of the Russian Federation for 2020–2022, project: Catalysis in Petroleum Refining and Oil and Gas Chemistry.

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