Enhanced piezoelectric properties of barium titanate single crystals with different engineered-domain sizes

Abstract

For tetragonal barium titanate (BaTiO3) single crystals, an electric field (E-field) applied along the [111]c direction can induce an engineered-domain configuration in these crystals. In this study, such engineered-domain configurations of different domain sizes were induced in BaTiO3 single crystals, and their piezoelectric properties were investigated as a function of domain size. Prior to this study, the dependences of the domain configuration on the temperature and E-field were investigated using a polarizing microscope in order to understand the optimum poling condition for fine- and coarse-domain configurations. We found that above the Curie temperature (TC) of 132.2 °C, when an E-field above 6.0kV∕cm was applied along the [111]c direction, an engineered domain with a fine-domain configuration appeared. Moreover, it was also found that this fine-domain configuration remained stable at room temperature without the E-field. On the other hand, the coarse-domain configuration was obtained upon poling at just below TC. Finally, the piezoelectric properties of 31 resonators with different domain sizes of 40–5.5μm were measured. As a result, it was found that the piezoelectric properties, such as d31 and k31, increased significantly with decreasing domain size.

Domain Wall Displacement is the Origin of Superior Permittivity and Piezoelectricity in BaTiO3 at Intermediate Grain Sizes

“…[40]) and/or that the strain field surrounding the 90º domain walls increases in the smaller grain sizes [10,41,42]. As the density of domain walls is clearly a defining variable to property coefficients in single crystal BaTiO 3 [36], it is tempting to speculate that an increase in domain wall density (as may be indicated in the present work by the increased diffuse scattering) may lead to increased property coefficients. However, the dielectric and piezoelectric coefficients do not correlate proportionally to the diffuse scattering, instead maximizing at ~2 μm.…”

“…In this model, the permittivity increases from grain sizes of 10 μm down to grain sizes of ~1 µm due to an increase in 90° domain wall density. In this model, it was assumed that the contribution of domain walls was due to their displacement or motion during perturbation; it was much later that the intrinsic response of domain walls themselves were clearly observed to enhance property coefficients (e.g., as shown by Wada et al in BaTiO 3 single crystals [36]). In the original model by Arlt et al, it was also assumed that the force constant for 90º domain wall displacement is independent of domain width.…”

Temperature dependence of the direct piezoelectric effect in relaxor-ferroelectric single crystals: Intrinsic and extrinsic contributions

“…Moreover, the intrinsic contribution, as measured along the non polar ͓001͔ C poling direction of each domain-engineered crystal, is also expected to increase as the first order ferroelectric-ferroelectric phase transition is approached. 25 There is significant evidence that the presence, rather than motion, of domain walls in domain-engineered barium titanate and potassium niobate leads to an increase piezoelectric response, [35][36][37][38][39] especially when the domain structure becomes very fine ͓Ͻ10 m ͑Ref. 38 and 39͔͒.…”

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…223 In general, enhanced electromechanical properties observed in materials with reduced domain size are associated with an increased domain wall density and their enhanced mobility. 150,224,225 Domain engineering refers to a technique employed to induce a stable and optimized domain size in a material so that maximized functional properties can be achieved. 150,151,224 Although domain size and grain size are related in polycrystalline materials ( Figure 2.18 (a)), domain engineering is also effective in single crystals.…”