Ferroelectric and Piezoelectric Properties of KNbO3 Ceramics Containing Small Amounts of LaFeO3

摘要: Dense KNbO3 ceramics have been successfully synthesized by pressure-less sintering under optimized heat-treatment conditions using a small amount of La2O3 and Fe2O3 additives. forms (K1-xLax)(Nb1-xFex)O3 solid solutions changes in the crystal system, depending on additive content, from orthorhombic to tetragonal at x 0.020, cubic 0.200 or higher. When only 0.002 mol (x=0.002) was added into KNbO3, highest value (98.8%) theoretical density obtained. This specimen showed symmetry with high Curie temperature 420°C, demonstrated well-saturated ferroelectric hysteresis loop large remanent polarization (Pr) 18 µC/cm2, which is comparable reported for pure fabricated hot pressing. Furthermore, x=0.002 planar electromechanical coupling ratio (kp) 0.17 piezoelectric d33 constant 98 pC/N, regardless unsaturated poling state.