Fabrication and properties of NaNbO 3 sintered by two-step method

Ferroelectric phase has been discovered in dense sodium niobate NaNbO3 ceramic sintered by two-step method. At ambient temperature, its absolute principal rhombohedral phase R3c rather than antiferroelectric phase Pbcm was detected by X-ray diffraction measurements. And its grains with small size were observed by scanning electron microscope. Its changes of dielectric properties, enhanced ferroelectricity, and weakened piezoelectricity are related and may be ascribed to the dominant ferroelectric phase R3c of small size grains, compared with those of NaNbO3 ceramic sintered by solid-state reaction procedure. The results demonstrate a relationship of phase transitions, domain rotation, and piezoelectric coupling mechanism: indicating the means to achieve stable ferroelectric state of NaNbO3 with small grain size by employing the two-step method, and its potential energy-storage application.