Semiconductor/relaxor 0–3 type composites without thermal depolarization in Bi0.5Na0.5TiO3-based lead-free piezoceramics

Abstract

Commercial lead-based piezoelectric materials raised worldwide environmental concerns in the past decade. Bi 0.5 Na 0.5 TiO 3 -based solid solution is among the most promising lead-free piezoelectric candidates; however, depolarization of these solid solutions is a longstanding obstacle for their practical applications. Here we use a strategy to defer the thermal depolarization, even render depolarization-free Bi 0.5 Na 0.5 TiO 3 -based 0-3-type composites. This is achieved by introducing semiconducting ZnO particles into the relaxor ferroelectric 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 matrix. The depolarization temperature increases with increasing ZnO concentration until depolarization disappears at 30 mol% ZnO. The semiconducting nature of ZnO provides charges to partially compensate the ferroelectric depolarization field. These results not only pave the way for applications of Bi 0.5 Na 0.5 TiO 3 -based piezoceramics, but also have great impact on the understanding of the mechanism of depolarization so as to provide a new design to optimize the performance of lead-free piezoelectrics.

Enhanced ferroelectric properties and thermal stability of Mn‐doped 0.96(Bi0.5 Na0.5)TiO3‐0.04BiAlO3 ceramics

“…A large number of attempts using methods based on chemical doping and forming composite have been exploited to improve T d of BNT‐based solid solutions . Zhang et al.…”

Bi0.5Na0.5TiO3:ZnO lead-free piezoelectric composites with deferred thermal depolarization

“…Our very recent work shows that when micrometer-sized ZnO particles are embedded in Bi 0.5 Na 0.5 TiO 3 -BaTiO 3 (BNT-BT) solid solution matrix to form 0-3 type composites, the thermal depolarization of BNT-BT solution can be deferred or eliminated. 12 However, this work still leaves some further questions to be explored. For example, is nano-sized ZnO still effective?…”

“…The BNT:xZnO composites were prepared by solid state reaction with sintering temperature of 950-1000 C for 0.5 h, detailed experimental descriptions are similar as that reported elsewhere. 12 Higher x value corresponds to lower sintering temperature since ZnO is a well known sintering aid and can lower sintering temperature. 13 Both X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements confirmed the composite structures.…”

Lead-free piezoceramics: Status and perspectives

“…92 At the same time, new materials (e.g., based on bismuth ferrite) 29 and new physical mechanisms are being discovered. In terms of new mechanisms, the opportunities to enhance depolarization temperature by either quenching 93 or using composites 94,95 and by hardening through hard second phases 96 seem particularly noteworthy.…”