The Properties Research Of SBT-NBT Piezoelectric Ceramics

Bismuth layer-structured ferroelectric ceramics with high Curie temperature, relatively low dielectric constant, low loss and low temperature coefficient of resonant frequency, making them become a candidate material in high temperature and high frequency resonance applications. Na_0.5Bi_4.5Ti₄O₁₅?NBT? and SrBi₄Ti₄O₁₅?SBT? are all four-layer orthogonal ferroelectric phase piezoelectric ceramics. However,to date, there are no reports of structure and properties of SBT ceramics with high NBT content.?1-x?SrBi₄Ti₄O_15-xNa_0.5Bi_4.5Ti₄O₁₅?SNBT? ceramics were prepared by using ordinary sintering process. In this work, we also change the calcination temperature and sintering temperature, vary the Bi content and improve the poling process. The crystal composition and piezoelectric properties of Sr_1-x(Na_0.5Bi_0.5)xBi₄Ti₄O₁₅ ceramics as a function of Na_0.5Bi_4.5Ti₄O₁₅ content were investigated. Curie temperature of SNBT solid solution ceramics slightly enhanced with the increase of Na_0.5Bi_4.5Ti₄O₁₅ content, and the excellent properties were obtained for Sr_1-x(Na_0.5Bi_0.5)xBi₄Ti₄O₁₅?x=0.10? ceramics sintered at 1000°C for 3h: d33=20pC/N, tan =0.28%, TC=575°C.In addition, the effects of various doping, such as Li₂CO₃, CeO₂ and?LiCe? modified on the structures and properties of 0.9SrBi4Ti4O15-0.1Na_0.5Bi_4.5Ti₄O₁₅ ceramics were studied. The properties of Sr_0.9(Na_0.5Bi_0.5)0.1Bi₄Ti₄O₁₅ + x wt% CeO₂ ceramics with x=0.50 were the best. They have a single phase of bismuth layer-structured. It is found that the TC shifts to high temperature slightly with the modification. The piezoelectric properties of SNBT ceramics were significantly enhanced and the dielectric loss sharply decreased with cerium doping. The piezoelectric constant d33 and the planar electromechanical coupling factor?k p?, thickness electromechanical coupling factor?k t? for the SNBT ceramics with 0.50wt% CeO2 modification were found to be 27 PC/N and 7.2%, 27.4%, respectively. Temperature dependence of d33 SNBT ceramics was found to be stable up to 500°C, which demonstrating that high-temperature piezoelectric applications are possible up to 500°C in Ce-modified strontium bismuth titanate ceramics.