Hardening behavior of Mn-modified KNN-BT thick films fabricated by aerosol deposition

Highly dense, 30 μm-thick 0.95(K0.5Na0.5)NbO3–0.05BaTiO3 (KNN-BT) lead-free films were successfully fabricated on alumina substrate by aerosol deposition (AD) and the effect of Mn doping (0 mol%, 0.5 mol% and 1.0 mol%) on the film properties was investigated. It was found that low field dielectric constant decreases by 36% for 0.5 mol% Mn doping and 42% for 1 mol% Mn doping. The loss factor was found to reduce by 19% for 0.5 mol% Mn doping and 43% for 1 mol% Mn doping. Based on the high field polarization–electric field measurement, we demonstrate that Mn induces hardening in KNN-BT thick films. The hardening is believed to be due to the pinning of the domains by dipolar defects at domain boundaries.