Effect of Na_2O additions on the sinterability and piezoelectric properties of lead-free 95(Na_(0.5)K_(0.5))NbO_3-5LiTaO_3 ceramics

摘要

As a candidate for lead-free piezoelectric materials, Na_2O excess 95(Na_(0.5)K_(0.5))NbO_3-5LiTaO_3 (NKN-5LT) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding Na_2O as a sintering aid. Abnormal grain growth in NKN-5LT ceramics was observed with varying Na_2O contents. This grain growth behavior was explained in terms of interface reaction-controlled nucleation and growth. The electrical properties of NKN-5LT ceramics were investigated as a function of Na_2O concentration. In the 1 mol percent Na_2O excess NKN-5LT samples sintered at 1050 deg C for 4h in air, electromechanical coupling factor and piezoelectric constant of NKN-5LT ceramics were found to reach the highest values of 0.43 and 230 pC/N, respectively.