Tape casting and electrical characterization of 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–0.5BCT) piezoelectric substrate

Recently, piezoelectric wafers/substrates have opened new opportunities for nondestructive evaluation (NDE) of structures in defense, aerospace, and industrial sectors. Such substrates can be easily made by tape casting of slurries where dispersants and binders play a critical role. In the present work, tape casting slurry of BZT-0.5BCT powder has been prepared using MEK-EtOH (solvent), phosphate ester (dispersant), polyvinyl butyral (binder), poly ethylene glycol and benzyl butyl pthalate (plasticizer). It was found that 1wt.% phosphate ester is sufficient for effective dispersion of BZT-0.5BCT to obtain a stable slurry. Variation of PVB content shows that at least 3wt.% PVB is required to obtain the workable green tape. The highest density (94% of true density), relative permittivity (1700 at 1kHz) and the high values of strain (0.23%) have been obtained for tape with 3wt.% PVB content and 65% solid loading after firing at 1500°C/4h.