Unidirectionally Textured CaBi₄Ti₄O₁₅ Ceramics by the Reactive Templated Grain Growth with an Extrusion

Dense CaBi 4 Ti 4 O 15 (CBT) ceramics with a unique texture were prepared by the reactive templated grain growth (RTGG) method using an extrusion technique. Plate-like Bi 4 Ti 3 O 12 (BIT) particles, a reactive template for CBT, were mixed with other oxide and carbonate powders and unidirectionally aligned by extrusion. During sintering, oriented CBT grains were formed in situ topotaxially on the oriented BIT particles, and the templated grain growth and their densification eventually fabricated textured CBT ceramics. X-ray diffraction measurements and scanning electron microscopic observations revealed that the plate-like CBT grains were unidirectionally oriented parallel to the extruding direction without uniaxial alignment. Textured CBT ceramics poled in the extruding direction exhibited electromechanical coupling coefficients ( k 33 ) and piezoelectric coefficients ( d 33 and g 33 ) more than two times as large as one of nontextured ceramics with the same composition.