Co-relation between Rietveld analysis, dielectric studies and impedance spectroscopy of the Ba1−xSrxTiO3 ceramics

• Published in: Journal of materials science. Materials in electronics 2024-06, Vol.35 (16), p.1077
• Main Authors: Devi, Sheela, Chaudhary, Shristi, Hashim, Mohd, Batoo, Khalid Mujasam, Hadi, Muhammad, Shirsath, Sagar E.
• Format: Article
• Language: English
• Subjects: Barium; Barium strontium titanates; Barium titanates; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coercivity; Curie temperature; Current carriers; Doping; Electrical properties; Ferroelectricity; Grain boundaries; Grain size; Materials Science; Microstructure; Nyquist plots; Optical and Electronic Materials; Permittivity; Solid phases; Spectrum analysis; Strontium; Substitution reactions; Temperature; Temperature dependence
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-024-12788-x

Barium strontium titanate (BST), with varying Sr doping levels ( x  = 0, 0.05, 0.075, 0.1, 0.15, 0.3), was successfully synthesized using the solid-state reaction technique. The aim was to investigate the microstructural, dielectric, and impedance properties as Sr doping increases. X-ray diffraction analysis revealed a tetragonal phase structure for these materials, belonging to the P 4 mm space group, confirmed via Rietveld refinement using the Fullprof suite. SEM analysis indicated the decrement in grain sizes ranging from 0.198 to 0.0582 μm as doping concentration increases. The temperature and frequency dependencies of the dielectric constant were examined, with the Curie temperature observed in the range of 295 to 351 K with decreasing trend with substitution of strontium in pure barium titanate, showing an increase in dielectric constant with rising temperatures and non-relaxor behavior. P–E loops of BST samples illustrated bulk ferroelectric behavior, with maximum values of retentivity and coercivity reaching 1.56 and 13.97, respectively, in the highly doped BST sample. Various analytical techniques, including Nyquist plots, real and imaginary components of impedance, conductivity measurements, modulus formalism, and determination of charge carrier activation energy, were employed to elucidate the relationships between microstructure and electrical properties. Temperature-dependent resistivity demonstrated the negative temperature coefficient of resistance (NTCR) behavior in Sr-doped barium titanate. Impedance studies revealed semicircular arcs in Nyquist plots, indicating contributions from both grains and grain boundaries. The formation of well-defined grains in the BST samples was further confirmed through modulus spectroscopy.