Low temperature consolidated lead-free ferroelectric niobate ceramics with improved electrical properties

There is a concerted effort to develop lead-free piezoelectric ceramics. (Na0.5K0.5)NbO3-based ceramics have good electrical properties, and are a potential replacement material for lead zirconate titanate piezoelectric ceramics. In this work a commercial powder based on (Na0.5K0.5)NbO3 with an initial particle size of similar to 260 nm was consolidated by spark plasma sintering (SPS). To avoid volatilization, high mechanical pressures were used to minimize the densification temperature. It was found that under a uniaxial pressure of 100 MPa, fully densified compacts can be prepared at 850 degrees C. Ceramics densified at such a low temperature demonstrate an unusually high remanent polarization (30 mu C/cm(2)) and high d(33) (146 pC/N). The improved ferroelectric properties are ascribed to the homogeneous, dense, and submicron grained microstructure achieved.