Dielectric properties of Al-doped Ti3SiC2 as a novel microwave absorbing material

Al-doped Ti3SiC2 powders were synthesized by solid state reaction under a vacuum atmosphere from Ti/Si/TiC powders, with an optimum Al doping content. Results showed that the Ti3SiC2 major phase could be generated at a temperature as low as 1250 °C through Al doping, and that the doped powders had a relatively narrow particle size distribution with a good dispersibility. The formation of Ti3Si1−xAlxC2 solid solution was further proved by XPS. The microwave dielectric parameters and reflection loss of the prepared Al-doped Ti3SiC2 samples were determined in the frequency range of 8.2–12.4 GHz. It was found that the sample synthesized at 1350 °C showed the high values in both the imaginary part of permittivity ε″ and dielectric loss tan δ, which were 4.39–7.32 and 0.57–0.78, respectively. For the microwave absorbing coating with a 2.6 mm thickness of the sample, a better reflection loss of almost below −12 dB was obtained in the whole frequency range of 8.2–12.4 GHz.