Kinetics of PbTiO₃ perovskite phase formation via an interfacial reaction

The kinetics of the formation of PbTiO₃ at the PbO/TiO₂ interface has been analyzed. The flux of Pb²⁺ and O^2- ions through the PbTiO₃ layer was used to derive the kinetics equation for the formation of the PbTiO₃ phase. On the basis of the parabolic growth kinetics of the PbTiO₃ interlayer, the reaction rate constant (k) for PbTiO₃ formation was determined as a function of the average diffusion coefficient of the Pb²⁺ ions (D̄_Pb2+). By employment of the data from diffusion couple experiments and the free energy values for the formation of the PbTiO₃ phase (ΔG_PBTiO(3)°) into the present kinetics equation, D̄_Pb2+ in the PbTiO₃ interlayer was calculated with respect to the corresponding temperature. The activation energy for diffusion (Q) and the diffusion constant (D₀) of Pb²⁺ ions in the PbTiO₃ layer could be evaluated from the Arrhenius plot of D̄_Pb2+.