Giant Piezoelectricity and High Curie Temperature in Nanostructured Alkali Niobate Lead Free Piezoceramics through Phase Coexistence.
Because of growing environmental concerns, the development of lead free piezoelectric materials with enhanced properties has become of great interest. Here, we report a giant piezoelectric coefficient (d33) of 550 pC/N and a high Curie temperature (TC) of 237 degC in (1 x y)K1 wNawNb1 zSbzO3 xBiFeO3 yBi0.5Na0.5ZrO3 (KNwNSz xBF yBNZ) ceramics by optimizing x, y, z, and w. Atomic resolution polarization mapping by Z contrast imaging reveals the intimate coexistence of rhombohedral (R) and tetragonal (T) phases inside nanodomains, that is, a structural origin for the R T phase boundary in the present KNN system. Hence, the physical origin of high piezoelectric performance can be attributed to a nearly vanishing polarization anisotropy and thus low domain wall energy, facilitating easy polarization rotation between different states under an external field.
Journal of the American Chemical Society