Frequency and temperature dependence of dielectric and electrical properties of radio-frequency sputtered lead-free K0.48Na0.52NbO3 thin films

Lead-free K0.48Na0.52NbO3 (KNN) ferroelectric thin films were prepared using the radio-frequency magnetron sputtering method. The crystallized KNN phase was confirmed using X-ray diffraction. The KNN thin film exhibited a well-saturated ferroelectric polarization-electric field hysteresis loop with high remanent polarization. The dielectric and electrical properties of the KNN thin film were investigated over a wide range of frequencies from 10 Hz to 1 MHz, and over a wide range of temperatures from 25 °C to 500 °C. The complex impedance relaxations are shown in an impedance Cole–Cole plot. With increasing temperature, the AC conductivity increased, which obeys the power law, σ(ω) = σ0 + Aωs. The activation energy for the conduction process is calculated to be 0.57 eV from the slope of the AC conductivity at the low frequency.