Alkaline niobate based lead-free ceramic fiber/polymer 1-3 composites: processing and electromechanical properties

The 1-3 type lead-free piezofiber/epoxy composites were prepared using Li, Ta and Sb modified (Na, K)NbO₃ compositions as the ceramic phase by means of fiber arrangement and epoxy cast. The dense and smooth piezoelectric ceramic fibers with a diameter of 250 μm or less were fabricated by extruding plastic mud pie through micro-holes drilled in a hard mould by means of a laser-cutter. The dielectric, piezoelectric, electromechanical coupling properties and acoustic impedance characteristic of the as-prepared 1-3 composites with different ceramic volume fractions were characterized and compared with the theoretical values as well as those of monolithic ceramics. A nearly pure thickness vibration mode with a resonance frequency over 2 MHz (sample thickness ~1 mm) was formed, together with a high electromechanical coupling coefficient (k _t  ~ 0.55–0.6), low acoustic impedances (Z ~ 9–14 MRayl) and relatively high piezoelectric voltage coefficient (g ₃₃ ~ 30 × 10⁻³ m²/C). The results indicate that those composites have potential to be transducer elements in various applications.