Enhancement of dielectric properties and conduction mechanism in BaTi0.85Sn0.15O3 for energy storage application

To achieve cost effective materials with improved dielectric properties, BaTiO3 and BaTi0.85Sn0.15O3 have been prepared by solid state reaction technique introducing a two step sintering method. The structure of the samples has been investigated by X-Ray diffraction (XRD) and Raman spectra at room temperature (RT ~ 300 K). In addition, crystallographic microstructures and grain morphology have been evaluated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) respectively. Apart this, the band structure along with density of states (DOS) are evaluated using first principle calculations for BaTiO3 and BaTi0.85Sn0.15O3. The band structure depicts bandgap of 1.80 eV and 1.82 eV for BaTiO3 and BaTi0.85Sn0.15O3 respectively. The DOS calculation displays the increase in hybridization of Ba2+ (A site) and Ti4+ (B site) cations with oxygen octahedra resulting in off-center displacement of cations in Sn doped BaTiO3 sample. A disordered cubic phase is obtained in BaTi0.85Sn0.15O3 sample sintered at 1350 °C resulting in the highest dielectric constant εr′ with a minimum loss tanδ. The conduction mechanism has been analyzed from the temperature and frequency dependence of resistivity ρ. The overall forecasts indicate BaTi0.85Sn0.15O3 annealed at 1350 °C to be a potential candidate for energy storage capacitive devices in the electronic industry. Microstructure-based dielectric properties, conductivity mechanism variations with Frequency and temperature as well as the anomalies in Band structures, capacitance and discharge energy density obtained for pure BaTiO3 and Sn doped BaTiO3. [Display omitted] •BaTi0.85Sn0.15O3 sintered at 1350°C for 3h has the highest dielectric constant εr′ with the lowest loss tanδ at 300K.•Pure BaTiO3 shows indirect bandgap of 1.80 eV while it becomes direct bandgap of 1.82eV for 15% replacement of Ti4+ by Sn4+.•Strong off-center displacement for Ba2+ and Ti4+ is observed in BTSO sample due to the hybridization with oxygen octahedra.•Electrical conductivity, σac, in BaTi0.85Sn0.15O3 annealed at 1350℃ shows maximum response to frequency of applied field.•BaTiO3 and BaTi0.85Sn0.15O3 samples are semiconductive in between 370 K to 415 K under a 1000 kHz applied electric field.•Capacitance (C) is maximum for BaTi0.85Sn0.15O3 sample annealed at 1350℃ and C=112.95 nF at room temperature.•The discharge energy density is maximum for BaTi0.85Sn0.15O3 sample annealed at 1350℃.