Dielectric Modulation Based on TiO ₂ Phase Transition Engineering

Abstract Phase transition engineering has been considered an effective means to modulate the dielectric properties of electromagnetic materials, endowing them with tunable properties. However, research on the specific mechanism by which phase transitions regulate dielectric properties remains relatively limited. Through a strategy of metal doping, the mechanism of phase‐change engineering for modulating electromagnetic properties is thoroughly investigated. In this study, transition metal doped TiO 2 supported on carbon substrates (denoted as C‐M/TiO 2 , C = carbon, M = Fe, Co, Ni) nanofibers are prepared using a simple electrospinning strategy combined with subsequent thermal treatment. The results show that the phase ratio of rutile‐TiO 2 to anatase‐TiO 2 can be easily adjusted by varying the type of transition metal dopant, which in turn regulated the conductivity and dielectric properties of the materials. Among the tested metals, Ni doping promoted the formation of a higher proportion of rutile‐TiO 2 , thereby exerting a more significant effect on the dielectric parameters. Specifically, the optimized C‐Ni/TiO 2 sample achieved a minimum reflection loss of −62.2 dB and a maximum effective absorption bandwidth of 6.2 GHz (with a thickness of 2.2 mm). This work provides valuable insights into the regulation of dielectric parameters through phase transition engineering.