Perfectness of Macrodomains of BaTiO3 Crystals

Abstract

Statistico-thermodynamical investigation is made on the size and density of reversely-polarized microdomains contained within a unidomain c -plate (or a macrodomain of a multidomain c -plate) of BaTiO 3 in thermal equilibrium at room temperature, with or without constant electric field applied. Microdomains treated here are confined to ones running through the crystal plate from the surface on the one side to the surface on the other side. It is found that a thinner crystal plate contains more reversely-polarized microdomains, and a plate thicker than about 2×10 -6 cm contains practically no reversely-polarized microdomains. Reversely-polarized microdomains tend to disperse rather than coalesce, and can hardly be depressed by electric field. Just below the Curie temperature, it is expected that the critical thickness is considerably larger than the above value, since the domain-wall energy per unit area is fairly small.