Piezoelectric Properties of Bismuth Layer-Structured Ferroelectric Ceramics with a Preferred Orientation Processed by the Reactive Templated Grain Growth Method

Abstract

Dense CaBi4Ti4O15 (CBT) and Na0.475Ca0.05Bi4.475Ti4O15 (NCBT) ceramics with a highly preferred {001} orientation were prepared by the reactive templated grain growth (RTGG) method. Plate-like Bi4Ti3O12 (BIT) particles were synthesized by a molten salt technique and used as the reactive template. The template particles were mixed with other oxide and carbonate powders and aligned by tape-casting. During the sintering, oriented CBT and NCBT were formed in situ topotaxially on the oriented BIT particles, and textured CBT and NCBT ceramics were eventually fabricated by the templated grain growth and densification. The Lotgering {001} orientation degree of the textured ceramics exceeded 90% for secondary-laminate sintered specimens. Textured CBT and NCBT ceramics poled in the perpendicular direction to the preferred <001> axis exhibited electromechanical coupling coefficient (k 33) and piezoelectric coefficients (d 33 and g 33) three times higher than the values for nontextured ceramics with the same composition.

Progress in Dual (Piezoelectric-Magnetostrictive) Phase Magnetoelectric Sintered Composites

“…Crystallographic texturing of piezoelectric grains in certain orientation can improve the piezoelectric, ferroelectric response because better spontaneous polarization can be achieved than in randomly oriented grain. Many researchers have reported the improvement of piezoelectric responses by incorporating the textured grain growth in the ceramic structure [58][59][60]. The most common fabrication processes for texturing are hot forging, hot pressing, gradient sintering, and templated grain growth.…”

“…Results have been reported in literature on the effect of texturing in both lead-based and lead-free materials including BaTiO 3 (BTO), Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT), (Na 1/2 Bi 1/2 )TiO 3 -BaTiO 3 (NBT-BT), and (K,Na)NbO 3 (KNN) [85][86][87][88]. The goal of this study was to implement the known texturing process in heterogeneous system consisting of varying crystal structure.…”

“…For this purpose, small amount (1-5 wt.%) of seed was mixed with the piezoelectric powder 0. 85 (NCZF) top and bottom layer and seeded PZT-15% PZN in the middle. The sample was kept for sintering in an air atmosphere for 50 hr soaking time so that the grains can grow along the preferred orientation of seed crystal.…”

Texture Engineering of Electronic Ceramics by the Reactive-Templated Grain Growth Method

“…Table 2 gives the piezoelectric and dielectric properties of textured CBT ceramics prepared by the RTGG method and randomly-oriented CBT prepared by the conventional method. 36,37 The electromechanical coefficients k t and k 33 of the RTGG-processed specimen were more than three times as high as those of the randomly oriented specimen and the values exceeded 50ಚ when processed by tape-casting. The piezoelectric constants d 33 and g 33 of the textured BLSF were also remarkably higher than those of the randomly oriented ceramics.…”

“…Figure 7 schematizes the processing and evaluation of CBT ceramics. 36,37 Fully dense and singlephase ceramics were obtained for NBT and CBT with a high degree ofƿ001|orientation ࢽ0.9; the piezoelectric properties of these ceramics were evaluated. The SEM images in Fig.…”