Magnetic MoS₂: a promising microwave absorption material with both dielectric loss and magnetic loss properties

In order to obtain magnetic MoS₂ and investigate the influence of magnetic moment on the microwave absorption properties of MoS₂, transition metal element Ni-doped MoS₂ (0-30 at%) was obtained by a hydrothermal synthesis. The results revealed that the low doping concentration (<10 at%) did not significantly change the crystal structure of MoS₂, and the Ni element formed a Ni _x Mo_1-x S₂ compound within the MoS₂ bulk phase. While the high doping concentration (10-30 at%) led to the formation of impurities. The hydrothermal products which were formed by the accumulation of pleated nanosheets looked like spherical flowers. As the doping concentration further increased, the spherical particles became more compact. The magnetization of MoS₂ could be increased by proper amount of Ni doping. When doping with 3 at% Ni (Ni-3), the M _s value increased from 0.53 emu g^-1 for non-doped MoS₂ to 0.93 emu g^-1. When the doping ratio was further increased, the M _s value of the material decreased. The zigzag edges and variations in the number of vacancies in the materials may be the root of changes in magnetic properties. The overall performance of Ni-3 was also the best in the examined doping range. Compared with non-doped MoS₂, the matching thickness decreased from 3.50 to 2.05 mm, while the minimum reflection loss value decreased from -55.18 to -58.08 dB, and the effective absorption bandwidth (<-10 dB) increased from 3.05 to 5.19 GHz. The excellent absorption performance of the doped materials can be attributed to the change of complex dielectric constant and complex permeability of MoS₂ and resulting in the improvement of loss capability. This study may introduce new opportunities for fully exploiting these nanocrystals for microwave absorption, even for diluted magnetic semiconductors.