Texturing of lead free piezoelectric ceramics
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Texturing of the lead-free system Ba0.92Ca0.08TiO3 (BCT) was investigated focusing on density, degree of texture and piezoelectric response. BCT templates were prepared in a two-step molten salt synthesis to achieve the anisotropic growth needed for the template morphology. Ba6Ti17O40 (B6T17) templates were synthesised, and then converted to BCT through a topotactic conversion process. BCT templates with a 20-50 µm diameter range and a 2-20 aspect ratio were obtained. The templates had a Lotgering factor F111=59.4%.Textured samples were prepared by tape casting and templated grain growth. As a reference, non-textured samples were prepared, and analysed together with the textured samples. A sintered BCT laminate, with a density of 93.4%, reached a texture degree of 42.7%. The highest measured direct and converse piezoelectric coefficients were d33=49±3 pCN-1 and d33= 140 pmV-1 respectively. Textured materials showed an increase in piezoelectric response compared to the non-textured materials. As many samples had a weak ferroelectric response, the foundation for comparing the effects of texture was somewhat impaired. This was probably caused by a combination of the low density and impurities in the samples. However, promising results with regard to enhancing piezoelectric response by texturing was observed and should be further investigated, focusing on achieving higher densities and thus higher degrees of texture in the ceramic.