Mesoporous anatase TiO₂ nanopowders with tunable electrical relaxation and low-k dielectric properties via sol-gel processing

Abstract Nanostructured TiO₂ nanopowders were synthesized via a modified sol–gel route followed by supercritical drying and thermal treatment at 400 °C in order to investigate their structural, electrical, and dielectric behaviors. Structural analyses confirmed the formation of a pure anatase TiO₂ phase with tetragonal structure and an average crystallite size of approximately 17 nm, demonstrating the successful synthesis of nanocrystalline TiO₂ without detectable secondary phases. Nitrogen adsorption–desorption measurements revealed a highly mesoporous structure with a specific surface area of about 102 m²·g⁻¹, which strongly contributes to the electrical response of the material. The electrical and dielectric properties were investigated over a broad frequency and temperature range using compacted mesoporous pellets. The AC conductivity increased with both frequency and temperature, following Jonscher’s universal power law, indicating a thermally activated hopping conduction mechanism. The dielectric relaxation behavior was further analyzed using the electric modulus formalism, where the peaks observed in the imaginary modulus (M″) confirmed the presence of temperature-dependent relaxation processes associated with charge carrier dynamics and interfacial polarization effects. At room temperature, the material exhibited a dielectric constant of approximately 157 together with a relatively low dielectric loss (tan δ ≈ 1.6), highlighting its potential for dielectric-related applications. The observed electrical response is mainly attributed to localized charge carrier hopping, oxygen-vacancy-related defects, grain boundary contributions, and interfacial polarization within the mesoporous TiO₂ nanostructure. Overall, these findings demonstrate that the synthesized mesoporous anatase TiO₂ nanopowders possess promising characteristics for potential applications in dielectric devices, sensors, and energy storage technologies.