Guangchang Wang

Modification of microstructure and electrical properties in (K,Na)NbO3-(Ba,Ca)ZrO3 ceramics by changing K/Na ratio

ABSTRACT 0.94(KxNa1-x)NbO3-0.06Ba0.8Ca0.2ZrO3 lead-free ceramics were prepared by the conventional solid-state method, and the effects of K/Na ratio on their piezoelectric properties were investigated in detail. Their grain sizes gradually decrease as the K/Na contents reach 60/40. By optimizing the K/Na ratio, an optimum piezoelectric behavior of d33∼270 pC/N and kp∼45% can be observed in the ceramics with x = 0.48. In addition, its piezoelectric activity was also strongly sensitive to the sintering temperatures and poling conditions, that is, d33 increases from 120 pC/N to 270 pC/N by a sintering temperature of 1160 °C and an optimum poling condition of >120 °C and 3 kV/mm. As a result, the modification of K/Na ratio is an effective way to further improve piezoelectric properties of KNN ceramics.