Fabrication and electrical properties of potassium niobate ferroelectric ceramics

Potassium niobate, KNbO3 (KN), ceramics were prepared by a modified conventional ceramic fabrication process to characterize their piezoelectric properties. The modified process involving two-stage calcination (first stage at 600 degrees C and second stage at 1000 degrees C is very effective in obtaining KN ceramics with a high density ratio > 96% and a high resistivity, p, of > 10(12) Omega.cm and that are nondeliquescent. The KN ceramics showed good piezoelectric properties in terms of the electromechanical coupling factor, k(33), the piezoelectric constant, d(33), and the mechanical quality factor, Q(m), which are 0.49, 91.7 pC/N, and 325, respectively. They were poled at a DC electric field of 5 kV/mm at 150 degrees C.