Synthesis of KNbO3 piezoelectric ceramics using citrate precursors

An aqueous-based citrate precursor route has been adopted for the synthesis of KNbO3 nanopowders. The required amount of KNO3 or C6H5O7K3 center dot H2O solution was mixed with citric Nb solution to form white precipitates, followed by heat treatment at 800 degrees C to produce KNbO3 nanopwders with an average particle size of 250-300 nm. The as-received nanopowder showed a well-sinterable property without using any additives, and the obtained KNbO3 ceramics showed saturated ferroelectric hysteresis loops of Pr = 22.9 mu c/cm(2) and E-c = 7.8 kV/cm at 1 hz. The excellent piezoelectric properties of kp = 0.35. Q(m) = 131. kq = 0.23, d(31) = -31 pC/N, and d(33) = 110 pC/N were obtained for KNbO3 ceramics derived from KNO3 solution, whereas K-p = 0.29, Q(m) = 96, k(31) = 0.20 d(31) = -45 pC/N, and d(33) = 115 pC/N were obtained for KNbO3 ceramics derived form C6H5O7K3 center dot H2O solution.