Effect of B2O3 on phase structure and electrical properties of CuO-modified (Ba,Ca)(Ti,Sn)O3 lead-free piezoceramics sintered at a low-temperature

This work investigated the effect of B2O3 on phase structure and electrical properties of CuO-modified (Ba0.95Ca0.05)(Ti0.90Sn0.10)O3-0.5CuO-xB2O3 (BCTSCu0.5Bx, 0≤x≤1.8 mol.%) lead-free ceramics sintered at a low sintering temperature (Ts=1200 °C). It was found that co-doping CuO and B2O3 is effective both on obtaining a dense microstructure and increasing the Curie temperature (TC) in BCTSCu0.5Bx ceramics. In addition to the sintering aids behavior of both CuO and B2O3 to reduce Ts, the increased TC mainly stems to the solid solution of B3+ which enters initially tetrahedral sites and then VO
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- and the sites between an apical O2− and Ti4+ with increasing its content. Good piezoelectric properties of d33=360 pC/N and kp=30% with an enhanced TC (49 °C) were obtained at x=1.4 owning to a proper proportion of rhombohedral and tetragonal phase even the Ts was as low as 1200 °C.