In this study, we investigated the optimum calcination temperature of lead-free 0.74(Bi_0.5Na_0.5)TiO₃-0.26SrTiO₃ (BNST) piezoelectric ceramics by analyzing the crystal structure, dielectric properties, and electric field-induced strain behavior. BNST ceramics prepared by conventional solid-state reaction methods at various calcination temperatures according to the industrial standard. All samples of BNST ceramics were subsequently sintered at 1,175℃ for 2 h. Crystal structure classification of the ceramics showed a single perovskite phase, with no second phase detectable for the samples calcined at 750℃ or higher. BNST samples calcined at 850℃ exhibited the most optimal values for itsand the common physical parameters of density = 5.518 g/㎤, ε = 1,871.837, tanδ = 0.047, and d₃₃^* = 874 pm/V.

In this paper, in order to develop optimum composition ceramics with excellent piezoelectric properties, (Na0.525K0.443Li0.037)(Nb0.823Sb0.08Ta0.037)O3 + 0.3 wt%Bi2O3 + 0.4 wt%Fe2O3 lead-free piezoelectric ceramics were synthesized by conventional soild-state method. The calcination temperature of columbite precursors were fabricated at temperature range from 950℃ to 1,150℃ and sintering aids with low melting point were added to densify these ceramics. Effect of calcination temperature on dielectric and piezoelectric properties of ceramics were investigated. the ceramics with B-site columbite precursors at temperature of 1,100℃ obtained the optimal values of d33=272 [pC/N], kp=0.51, Qm=102, εr=978.