Important influence of Bi deficiency on the conducting property of Na0.5Bi0.5TiO3 perovskite oxide

Abstract

Recently it has been reported that low levels of Bi nonstoichiometry (only ±1 atomic %) in the nominal starting composition of Na0.5Bi0.5TiO3 (NBT) ceramics can lead to dramatic changes in the conduction property. Present article present the results of powder XRD, 23Na MAS NMR and impedance spectroscopy in nominal starting compositions, Na0.5Bi0.5+xTiO3+3x/2 with x = 0.0 and − 0.02. Room temperature XRD data analysis indicates both NBTs have a rhombohedral (space group R3c) structure. While, 23Na MAS NMR results demonstrate a complex local structure and significant disordering of Na coordination environment. Impedance spectroscopy reveals high levels of oxide-ion conduction in NBT. 2 at-% Bi-deficient NBT (Na0.5Bi0.48TiO2.97) exhibits higher conductivity of σ∼1.3 × 10−4 S/cm at 500 °C and activation energy, Ea = 0.85 eV. Present results therefore substantiate the A-site nonstoichiometry sensitive electrical property of NBT.Recently it has been reported that low levels of Bi nonstoichiometry (only ±1 atomic %) in the nominal starting composition of Na0.5Bi0.5TiO3 (NBT) ceramics can lead to dramatic changes in the conduction property. Present article present the results of powder XRD, 23Na MAS NMR and impedance spectroscopy in nominal starting compositions, Na0.5Bi0.5+xTiO3+3x/2 with x = 0.0 and − 0.02. Room temperature XRD data analysis indicates both NBTs have a rhombohedral (space group R3c) structure. While, 23Na MAS NMR results demonstrate a complex local structure and significant disordering of Na coordination environment. Impedance spectroscopy reveals high levels of oxide-ion conduction in NBT. 2 at-% Bi-deficient NBT (Na0.5Bi0.48TiO2.97) exhibits higher conductivity of σ∼1.3 × 10−4 S/cm at 500 °C and activation energy, Ea = 0.85 eV. Present results therefore substantiate the A-site nonstoichiometry sensitive electrical property of NBT.