Size effect of barium titanate: fine particles and ceramics

Abstract

The size effect of ferroelectric materials is one of the most important issues to develop next-generation dielectric devices. In this paper, we reviewed our studies on the size effects of barium titante (BaTiO 3 ) fine particles and ceramics. In the size effect of BaTiO 3 fine particles, the maximum of dielectric permittivity was observed at a particle size of around 140 nm, and was explained by the composite structure model including a gradient lattice strain layer (GLSL) having a very high permittivity. In contrast, the grain size effect of BaTiO 3 ceramics, where the permittivity showed a maximum at a grain size of about 1.1¯m, was interpreted as the superposition effect of domain-wall contributions and grain boundary effect.

Plastic Deformation of BaTiO3Ceramics by High-pressure Torsion and Changes in Phase Transformations, Optical and Dielectric Properties

“…[32,33] Earlier papers reported that the optimum grain size to achieve high dielectric constants was in the range of 700-1,300 nm. [2,3,5] However, this present work suggests that the optimum grain size can shift even to the nanometer level after severe straining. The increase in the dielectric constant by nanograin formation through HPT processing is consistent with the theoretical models based on elastic field energy and domain wall energy.…”

“…Therefore, the increase in dielectric constant is not due to the effect of dielectric loss. The dielectric constant of 5,000-14,000 after N = 5 is higher than values reported in the literatures, [1][2][3][4][5] suggesting that the current material should be promising for high-capacitance capacitors and for electronic devices that need efficient mechanicalelectric energy conversion, provided that the material can be produced with a reasonable cost.…”

“…[2] The reduction of optimum grain size is a challenging task for the development of high-capacitance multilayered ceramic capacitors. [3] In summary, when severe plastic strain is introduced into BTO powders at room temperature, nanograins are formed and a tetragonal-to-cubic phase transformation occurs. The formation of cubic phase and its stability is facilitated by straining.…”

“…Barium titanate, BaTiO 3 (BTO), which belongs to the group of perovskite oxides with the general ABO 3 formula, has received much attention because of its dielectric, [1][2][3][4][5] piezoelectric [1,5,6] and ferroelectric [7,8] properties, as well as its mechanical and chemical stability. [9] Moreover, BTO has been widely investigated for its optical properties, [10] photoluminescence (PL), [11,12] photocatalysis, [13] proton conductivity [14] and phase transformations.…”

“…The increase in the BTO dielectric constant caused by HPT processing should be mainly due to the effect of grain size, [2][3][4] and partly due to good consolidation. [32,33] Earlier papers reported that the optimum grain size to achieve high dielectric constants was in the range of 700-1,300 nm.…”