Preparation of [110] Grain Oriented Barium Titanate Ceramics by Templated Grain Growth Method and Their Piezoelectric Properties

Abstract

[110]-oriented barium titanate (BaTiO3) ceramics were prepared by templated grain growth (TGG) method using [110]-oriented BaTiO3 platelike particles as a template and hydrothermal BaTiO3 sphere particles with different particle sizes as a matrix. The degree of orientation along the [110] direction, F110, was measured using an X-ray diffraction (XRD) pattern by the Lotgering method. To obtain both a high density and a high F110, the preparation conditions were optimized as functions of matrix particle size, volume fraction of the template to the matrix, and sintering temperature. As for the results, BaTiO3-grain-oriented ceramics with a high density of more than 96% were successfully prepared despite various F110 values from 0 to 98%. Scanning electron microscopy (SEM) revealed that their average grain sizes were always approximately 75 µm despite various F110 values and there were no anisotropic microstructures. These grain-oriented BaTiO3 ceramics were poled at 100 °C, and their piezoelectric properties were measured using a resonance–antiresonance method and a piezo d33 meter for d31 and d33 piezoelectric constants. As for the results, the d31 values were almost constant at -50 pC/N despite various F110 values, while the d33 values increased with increasing F110 values, and at around an F110 of 85%, d33 reached a maximum of 788 pC/N.

Enhancement of piezoelectric constant d33 in BaTiO3 ceramics due to nano-domain structure

“…10)12) Especially, Wada et al 13) reported a surprisingly high d 33 value of 788 pC/N in [110]-oriented BaTiO 3 ceramics prepared by templated grain growth method. Although they mentioned this superior piezoelectric response was mainly due to orientational effect, they also found that highly [110]-oriented BaTiO 3 ceramics with high d 33 values had much finer domain sizes than one with relatively low d 33 values.…”

“…Although they mentioned this superior piezoelectric response was mainly due to orientational effect, they also found that highly [110]-oriented BaTiO 3 ceramics with high d 33 values had much finer domain sizes than one with relatively low d 33 values. 13) On the other hand, Shao et al recently reported that average grain size, rather than domain width, significantly influences the piezoelectric properties in normally sintered BaTiO 3 ceramics. 14) They revealed that the piezoelectric constant d 33 values decrease from 419 pC/N to 185 pC/N when its average grain size increases from 3.5 to 9.5¯m, while its average domain width remains approximately constant at around 0.24¯m.…”

Electric-field-induced giant strain in Bi0.5Na0.5TiO3-based single crystals: Influence of high-oxygen-pressure annealing

“…Lead-free perovskite ferroelectrics of BaTiO3 (BT)-based materials, 1)-11) (Bi,K,Na)TiO3 12)-21) and (Ag, K,Li,Na)NbO3, -25) has been considered as a promising lead-free material because of its high Curie temperature (TC) of 300-400°C and superior piezoelectric properties. Recent investigations 2)-5), 72) have shown that BT ceramics with a grain size of ~100 nm show a large piezoelectric strain constant (d33) in which engineered domain configurations 72)-75) probably enhance the piezoelectric properties. Since materials properties show a marked temperature dependence near the transition temperature; phase transitions occurring near room temperature restrict the practical applications of BT.…”

Grain-size dependence of piezoelectric properties in thermally annealed BaTiO₃ ceramics

“…The d 33 value of 529 pC/N with an electromechanical coupling factor of 53% is the highest value reported so far for conventionally prepared randomly oriented BT ceramics besides the exceptionally high d 33 value of grainoriented BT ceramics. 26) The d 33 values after the annealing were remarkably large in comparison to the value of the sample without the heat treatment. This enhancement was due to the annealing out of the surface mechanical damaged layers and relaxation of the induced lattice strain.…”