Electrical properties of lead-free 0.98(Na0.5K0.5)NbO3-0.02Ba(Zr0.52Ti0.48)O3 piezoelectric ceramics by optimizing sintering temperature

Lead-free 0.98(Na0.5K0.5)NbO3-0.02Ba(Zr0.52Ti0.48)O-3 [0.98NKN-0.02BZT] ceramics were fabricated by the conventional mixed oxide method with sintering temperature at 1,080 degrees C to 1,120 degrees C. The results indicate that the sintering temperature obviously influences the structural and electrical properties of the sample. For the 0.98NKN-0.02BZT ceramics sintered at 1,080 degrees C to 1,120 degrees C, the bulk density increased with increasing sintering temperature and showed a maximum value at a sintering temperature of 1,090 degrees C. The dielectric constant, piezoelectric constant [d(33)], electromechanical coupling coefficient [k(p)], and remnant polarization [P-r] increased with increasing sintering temperature, which might be related to the increase in the relative density. However, the samples would be deteriorated when they are sintered above the optimum temperature. High piezoelectric properties of d(33) = 217 pC/N, k(p) = 41%, dielectric constant = 1,951, and ferroelectric properties of P-r = 10.3 mu C/cm(2) were obtained for the 0.98NKN-0.02BZT ceramics sintered at 1,090 degrees C for 4 h.