Gigantic Electrostrain in Duplex Structured Alkaline Niobates

We demonstrate that an exceptionally large strain can be induced in CaZrO3-modified alkaline-niobates by electric fields. The maximum induced strain of our niobate-based ceramics could reach more than 1,000 pm/V, which is a much higher value than that of commercial soft PZT ceramics. Atomic-scale annular bright-field (ABF) and annular dark-field (ADF) scanning transmission electron microscopy (STEM) directly revealed that individual single grains were composed of an electrically duplex core–shell structure; relaxor-like cores and paraelectric shells. Based on this ABF STEM analysis along with electrical measurements, a plausible mechanism explaining the high strain effect in the present work was suggested. This new material offers an unprecedented opportunity to produce efficient Pb-free piezoelectrics for applications that require large electrostrictive motion.