Synthesis of non-porous and nanocrystalline lanthana-doped zirconia layers by MOCVD method at low temperatures and pressure

Abstract

Amorphous and nanocrystalline lathana-doped zirconia layers were synthesized by the MOCVD method using La(tmhd)3 and Zr(tmhd)4 as reactants on planar and tubular quartz glass substrates. The synthesis temperature was in the range of 500–700 °C. The gas pressure in the CVD reactor was modified between 3 × 103 and 6 × 103 Pa. Argon and air were used as carrier gases. Air was also necessary for oxidation of carbon, which is a solid by-product of reactant pyrolysis. Other synthesis parameters were selected in order to obtain a value of the extended criterion Grx/Rex2 below 0.01. Then, laminar gas flow in the CVD reactor will be maintained. The surface, as well as the cross-section of deposited layers were observed using a scanning electron microscope (SEM). Their chemical composition was investigated by means of EDS analysis. XRD investigations on obtained layers were also performed. There was correlation between the chemical composition of reactants and obtained layers when the synthesis process was controlled by reactant diffusion to the substrate. The phenomenon of La3+ ion segregation in obtained layers was also observed. The layers exhibited good adhesion to the substrate.