High dielectric constant, relaxor behavior and phase transitions in Na0.5Bi0.5TiO3 nanorods

We report on relaxor-ferroelectric behavior, ferroelectric to anti-ferroelectric transition and superior dielectric properties of Na0.5Bi0.5TiO3 nanorods synthesized through hydrothermal technique. Na0.5Bi0.5TiO3 nanorods are seen to crystallize in rhombohedral crystal structure. Ferroelectric to anti-ferroelectric transition is observed at 450 K, where the dielectric loss attains its maximum value. Maxwell-Wagner interfacial polarization causes the dielectric constant to be high at room temperature (9 x 105). Dielectric loss at low frequencies is observed to be minimum. Non-Debye relaxation process in Na0.5Bi0.5TiO3 nanorods are clearly seen from the frequency and temperature dependent dielectric studies. Jonscher's relation is employed to analyze the frequency dependent conductivity at various temperatures and the activation energy (Ea) value is observed to be 0.48 +/- 0.02 eV. Structural-oxygen vacancy defect-dielectric property correlation is established through a detailed dielectric property analysis in Na0.5Bi0.5TiO3 nanorods.