Flux growth of 0.94[Na0.5K0.5NbO3]–0.06LiNbO3 piezo-/ferroelectric crystals for long duration and high temperature applications

Abstract

High quality lead free ferroelectric single crystals of 0.94[Na_0.5K_0.5NbO₃]–0.06LiNbO₃ (NKLN) were grown by the self-flux method. The crystals were characterized for structural and dielectric properties, piezo/ferro response (both on the macro and microlevel) and electrical behavior. The characterization confirmed a perfectly homogeneous stoichiometry having negligible defects in the sample. Further, the crystals were found to exhibit high Curie phase transition (~420 °C) with a high value of d₃₃ coefficient (=115 pC N⁻¹) and remnant polarization (=4.01 μC cm⁻² at 30 °C). Its pyroelectric coefficient was found to be ~309.8 μC m⁻² °C⁻¹. In addition, the crystals did not show any fatigue. Further, ferroelectric domains were analyzed using piezoresponse force microscopy and the effective d₃₃ coefficient on the microlevel was calculated to be ~80 pm V⁻¹ after a 20 min relaxation of 75 V induced bias. The results suggest NKLN crystals to be a very promising material in the family of available lead free materials for various ferroelectric applications.