Giant electrostrictive coefficient in rapidly cooled nanodisordered KTa_1-xNb_xO₃lead-free single crystals

The temperature dependent electrostrictive effect, with respect to increasing the cooling rate to a cooling temperature, was quantitatively investigated in potassium tantalate niobate (KTN) lead-free single crystals above and near Curie temperature (TC). High work-function Pt electrodes are used to minimize the effect of charge injection, and the electric field induced displacement was measured with Michelson interferometry. It was found that a giant electrostrictive coefficient of 696 × 10-16 m2/V2 could be obtained at a high cooling rate of 0.75 °C/s to a temperature of TC + 4.5 °C due to the evolution of polar nano-regions, which is one order of magnitude larger than the previously reported value in KTN crystals. This strengthens the realization of replacing toxic lead-based electrostrictive materials with environmentally friendly KTN materials in real world applications.