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<p>Lead-free composite ceramics were created using the traditional solid-state method and thoroughly examined to clarify the relationship between charge-transport mechanisms, dielectric relaxation, and microstructure. Tetragonal perovskite BaTi<sub>0.9</sub>Zr<sub>0.1</sub>O<sub>3</sub> and cubic spinel Li<sub>0.5</sub>Fe<sub>2.5</sub>O<sub>4</sub> phases were shown to coexist by X-ray diffraction without any discernible secondary impurities, whereas FESEM showed progressive grain refinement as the ferrite content increased. Interfacial polarization was strengthened by the decrease in grain size as well as the rise in microstrain and defect density. The real and imaginary dielectric permittivities showed a strong temperature dependency controlled by Maxwell–Wagner interfacial polarization, as well as strong frequency dispersion. Thermally activated, non-Debye relaxation indicated by electric modulus analysis had a dispersion of relaxation durations; time–temperature superposition was confirmed by normalized M″ spectra collapsing onto a master curve. AC conductivity changed from small-polaron hopping to correlated barrier hopping conduction as a function of temperature, according to Jonscher’s universal power law. ZBLF3 had the lowest activation energy and the fastest relaxation, according to Arrhenius analysis, which produced activation energies of 0.41–0.62&#xa0;eV. ZBLF3 is the composition that best balances high dielectric permittivity, regulated loss, quick relaxation, and improved AC conductivity among those examined. For lead-free ferroelectric ferrite composites used in tunable capacitors and multipurpose electronic devices that operate throughout a broad frequency and temperature range, the results offer precise design directives.</p>

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Grain size effect on electric modulus, scaling and conductivity of BZT-LF ceramic composites

  • 期刊论文

  • 发表日期：

    2026年5月4日

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  • Ganapathi Rao Gajula,
  • Lakshmi Rekha Buddiga,
  • Ch. Arun Kumar,
  • Vadamala Purandhar Reddy,
  • G. V. S. S. Sarma,
  • B. Sambaiah

摘要

Lead-free composite ceramics were created using the traditional solid-state method and thoroughly examined to clarify the relationship between charge-transport mechanisms, dielectric relaxation, and microstructure. Tetragonal perovskite BaTi0.9Zr0.1O3 and cubic spinel Li0.5Fe2.5O4 phases were shown to coexist by X-ray diffraction without any discernible secondary impurities, whereas FESEM showed progressive grain refinement as the ferrite content increased. Interfacial polarization was strengthened by the decrease in grain size as well as the rise in microstrain and defect density. The real and imaginary dielectric permittivities showed a strong temperature dependency controlled by Maxwell–Wagner interfacial polarization, as well as strong frequency dispersion. Thermally activated, non-Debye relaxation indicated by electric modulus analysis had a dispersion of relaxation durations; time–temperature superposition was confirmed by normalized M″ spectra collapsing onto a master curve. AC conductivity changed from small-polaron hopping to correlated barrier hopping conduction as a function of temperature, according to Jonscher’s universal power law. ZBLF3 had the lowest activation energy and the fastest relaxation, according to Arrhenius analysis, which produced activation energies of 0.41–0.62 eV. ZBLF3 is the composition that best balances high dielectric permittivity, regulated loss, quick relaxation, and improved AC conductivity among those examined. For lead-free ferroelectric ferrite composites used in tunable capacitors and multipurpose electronic devices that operate throughout a broad frequency and temperature range, the results offer precise design directives.