The Effect of Grain Boundary Charge on Ferroelectric Transitions in Nanograin BaTiO$_{3}$

We have recently reported dense polycrystalline BaTiO$_{3}$ that has sub-100 nm grains. As grain size decreases, the electrical field due to grain boundary charge extends to an increasingly larger fraction of the grain giving rise to a size effect that is fundamentally different from those previously considered in the literature. Using Ginsberg Landau theory we have modeled this effect on ferroelectric transition, polarization/phase distribution and dielectric/piezoelectric responses, and compared it with the experimental results of BaTiO$_{3}$ (XRD, TEM, and $\varepsilon (T))$. Such nanograin ferroelectric ceramics, currently available at sub-10 nm grain size, are of considerable interest for the next-generation microelectronic component applications. A related grain boundary effect on phase transition has also been reported in coarse grain and bicrystal SrTiO$_{3}$.