Synthesis and Properties of Vanadium Oxide Nanocoatings on the Surface of Polycrystalline α-Al2O3

Abstract

Vanadium oxide nanocoatings of various thicknesses were synthesized by the atomic layer deposition (ALD) through cyclic alternating treatment of polycrystalline α-Al₂O₃ plates with vapors of vanadium(V) oxochloride and water. Diffuse reflectance spectroscopy, demonstrated that, depending on the number of treatment cycles, complexes of various structures are generated on the surface, containing distorted aluminovanadate structures, layers with tetrahedral vanadium coordination, and polyhedra, in which the vanadium atom environment coordinated with oxygen is similar to the state in crystalline V₂O₅. Based on the results of studies using an atomic force microscope, it was found that depending on the thickness of the growing layer, the surface morphology and the degree of its overlap change. After 600 cycles of treatment with vapors of vanadium(V) oxochloride and water, a coating is formed that completely covers the surface of the original substrate. A composition based on polycrystalline α-Al₂O₃ with a functional vanadium oxide layer exhibits sensor properties in relation to such components of the gas environment as NO₂, CO, NH₃, H₂S, H₂.