Chemical Vapour Deposition of Scandia-Stabilised Zirconia Layers on Tubular Substrates at Low Temperatures

Abstract

The paper presents results of investigation on synthesis of non-porous ZrO2-Sc2O2 layers on tubular substrates by MOCVD (metalorganic chemical vapor deposition) method using Sc(tmhd)3 (Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)scandium(III), 99%) and Zr(tmhd)4 (Tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)zirconium)(IV), 99.9+%) as basic reactants. The molar content of Sc(tmhd)3 in the gas mixture was as follows: 14, 28%. The synthesis temperature was in the range of 600–700 °C. The value of extended Grx/Rex2 expression (Gr-Grashof number, Re-Reynolds number and x-the distance from the gas inflow point) was less than 0.01. The layers were deposited under reduced pressure or close to atmospheric pressure. The layers obtained were tested using scanning electron microscope (SEM) with an energy dispersive X-ray spectroscope (EDS) microanalyzer, X-ray diffractometer and UV-Vis spectrophotometer. The layers deposited were non-porous, amorphous or nanocrystalline with controlled chemical composition. The layers synthesized at 700 °C were nanocrystalline. ZrO2-Sc2O3 layers with 14 mol.% Sc2O3 content had a rhombohedral structure.