Low-temperature dielectric response of NaTaO3 ceramics and films

In this work, NaTaO3 ceramics are prepared by conventional mixed oxide method and NaTaO3 films are deposited by RF magnetron sputtering on Si/SiO2/TiO2/Pt substrates. The dielectric response of the obtained NaTaO3 ceramics and films is analyzed as a function of frequency and temperature. Between 1 kHz and 1 MHz, the dielectric permittivity of NaTaO3 ceramics is frequency independent and increases on cooling up to ∼324, which is the highest value ever reported for NaTaO3 ceramics. In contrast, NaTaO3 films exhibit a dielectric relaxation between ∼20 and 30 K, following the Arrhenius law with activation energy ∼51 meV and pre-exponential term ∼10−15 s and attributed to polaron hopping.