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

TLDR

The authors employed reactive templated grain growth, mixing plate‑like Bi₄Ti₃O₁₂ templates with CaBi₄Ti₄O₁₅ or Na₀.₄₇₅Ca₀.₀₅Bi₄.₄₇₅Ti₄O₁₅ powders, aligning them by tape‑casting to produce dense ceramics with a highly preferred {001} orientation. Resulting textured CBT and NCBT ceramics exhibited a Lotgering {001} orientation degree exceeding 90 % and, when poled perpendicular to the <001> axis, displayed electromechanical coupling and piezoelectric coefficients roughly three times higher than those of nontextured counterparts.

Abstract

Dense CaBi 4 Ti 4 O 15 (CBT) and Na 0.475 Ca 0.05 Bi 4.475 Ti 4 O 15 (NCBT) ceramics with a highly preferred {001} orientation were prepared by the reactive templated grain growth (RTGG) method. Plate-like Bi 4 Ti 3 O 12 (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 &lt;001&gt; 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.