Enhanced microwave absorption properties of Ti3AlC2 particles modified by a facile preoxidation strategy

Abstract

MAX phases are considered to be promising microwave absorbing materials in fifth-generation (5G) communications, but their high electrical conductivity causes impedance mismatching, weakening their ability to absorb microwaves. Here, we present a universal preoxidation strategy to improve the impedance matching and the microwave absorption performance of a Ti₃AlC₂ MAX phase absorbing material. The microwave absorption properties of Ti₃AlC₂ particles were enhanced after preoxidation at temperatures of 500–700 °C for only 30 min in air, as compared with unoxidized Ti₃AlC₂ particles. More interestingly, the 600 °C-preoxidized Ti₃AlC₂ material reached a minimum reflection loss (RL_min) value of −50.56 dB at 8.87 GHz, superior to −12.36 dB at 12.82 GHz for the original Ti₃AlC₂ material. The preoxidized Ti₃AlC₂ particles were covered by a thin oxidation layer comprising both amorphous TiO₂ (a-TiO₂) and rutile TiO₂ (R-TiO₂). The oxidation layer endows the preoxidized Ti₃AlC₂ particles with good impedance matching, and a large number of nano-interfaces of a-TiO₂/R-TiO₂ and micro-interfaces of a-TiO₂/Ti₃AlC₂ also contribute to the dielectric loss mechanism, thus improving its microwave absorption ability. This work provides a practical strategy for the fundamental study and the optimal design of MAX microwave absorbing materials.