Bismuth sodium titanate based lead-free ceramic/epoxy 1–3 composites: fabrication and electromechanical properties

Abstract

The 1–3 piezocomposites based on 0.96Bi0.5(Na0.84K0.16)0.5TiO3–0.04SrTiO3 (BNKT–ST) were fabricated by a modified dice-fill method. Electro-mechanical properties of the composites as a function of the ceramic volume fraction (v) were measured and compared with theoretical values as well as with those of monolithic ceramics. The as-prepared piezocomposite with v = 0.276 showed a clear single thickness mode with a relatively high resonance frequency of more than 2 MHz, together with a relatively high piezoelectric strain constant (d 33 ~ 104 pC/N), a high thickness coupling coefficient (k t ~ 0.547), low acoustic impedance (Z ~ 9 Mrayls) and a large piezoelectric voltage coefficient (g 33 ~ 91.5 × 10−3 m2/C). From the practical application point of view, these promising results indicate that the BNKT–ST ceramic/epoxy 1–3 composite has great potential to be used in biomedical ultrasonic transducers as well as nondestructive evaluations.