Phase Transition Kinetics in Bi₃NbO₇ Evaluated by in situ Isothermal Conductivity Measurements

Kinetics of phase transformation from pseudocubic to tetragonal phase
in Bi₃NbO₇ solid solution is studied by using the ac impedance method under isothermal conditions. Conductivity of the investigated compound is used to characterize the kinetic process of the transition. The Avrami exponent and the activation energy of phase transition are around 1.5 and 3.5eV, respectively. These kinetic parameters reveal that the pseudocubic-tetragonal transition in Bi₃NbO₇ belongs to a three-dimensional diffusion-controlled
growth with zero nucleation rate.