Time-dependent ferroelectric transition in Pb_(1-x)(Zr _0.4Ti_0.6)_(1-x/4)O₃ - XLa system

Ferroelectric transition involves tiny shift of ions within unit cell, thus being intrinsically a very fast process without apparent time-dependence. Contrary to this conventional wisdom, here we report a time-dependent ferroelectric transition, which occurs in hours. The system studied was Pb _(1-x)(Zr_0.4Ti_0.6)_{(1- x/4)}O₃ - xLa system with relaxor-forming dopant La³⁺. The time-dependent ferroelectric transition occurs at the ferroelectric/relaxor crossover composition range of 0.09 < x ≤ 0.16. In these compositions, in situ Raman spectroscopy and transmission electron microscopy reveal very slow growth of ferroelectric phase. Dielectric measurement shows isothermal kinetics of the transition. The slow ferroelectric transition can be understood as being caused by the slowing-down of the otherwise fast growth of polar nano-domains due to the random local field caused by La³⁺, so that long time is needed to achieve long-range order macroscopic ferroelectric phase.