Temperature-dependent defect dipoles polarization of (La, Nb) co-doped TiO2/PEI microwave absorption materials

Abstract

Point defect engineering has emerged as a key strategy to pursue efficient microwave absorption (MA) by effectively balancing impedance matching and polarization loss. Nevertheless, the detailed interplay between the temperature-driven dielectric relaxation characteristics and the absorption dissipation mechanisms remains an area that requires deeper exploration. Here, (La0.5Nb0.5)xTi1-xO2/polyetherimide (x = 0, 0.25%, 0.5%, and 1%) composites were prepared by co-doping TiO2 with donor (Nb5+) and acceptor (La3+) ions. As the concentration of point dipoles increases, the enhanced polarization loss significantly amplifies MA dissipation, demonstrating substantial potential for high-temperature applications at x = 0.5%. Notably, the point dipole polarization model provides a more comprehensive explanation of the relaxation time (τ), activation energy (Wη), and T. This behavior is attributed to strong polarization loss resulting from short-range electronic motion suppressed by those defect clusters, which provides a theoretical foundation for further understanding the mechanisms of microwave dissipation and high-temperature absorption potential.