Fabrication And Microwave Absorption Properties Of NiCo₂S₄-Based Composites

Bimetallic sulfides have excellent dielectric loss capability and chemical stability and can be used as electromagnetic wave absorbing materials.In this work,three composites,NiCo₂S₄@Mn₃O₄,NiCo₂S₄@CuO and NiCo₂S₄/carbon microspheres,were prepared.The compositions and micromorphologies have been characterized and analyzed by XRD,XPS,SEM,TEM,FTIR and Raman spectroscopy,and the electromagnetic parameters of the samples have been measured by vector network analyzer（VNA）.The studies and results are as follows:（1）NiCo₂S₄@Mn₃O₄ composite electromagnetic wave absorbing materials were prepared by the high-temperature calcination method and hydrothermal method using Ni（NO₃）₂·6 H₂O,Co（NO₃）₂·6 H₂O,CH₄N₂O,Na₂S·9 H₂O and KMn O₄ as raw materials.The effects of Mn₃O₄ prepared at four hydrothermal temperatures on the overall microscopic morphology and microwave absorption properties of the composites were investigated.The results indicated that when the hydrothermal temperature reached160°C,Mn₃O₄ grew uniformly on the surface of NiCo₂S₄ and the composite formed a shell-core structure.The minimum reflection loss of-54.4 GHz was acquired at a frequency of 11.4 GHz for the NiCo₂S₄@Mn₃O₄ composite with a thickness of 2.4 mm,and the maximum effective absorption bandwidth of 5.36 GHz was achieved at a thickness of 1.8 mm.（2）NiCo₂S₄@CuO composites were prepared by high temperature calcination method and hydrothermal method using Ni（NO₃）₂·6 H₂O、Co（NO₃）₂·6 H₂O、Na₂S·9H₂O and Cu Cl₂·2 H₂O as ingredients and PVP as surfactants.The impacts of NiCo₂S₄and CuO mass ratio on the electromagnetic wave absorption properties of the composites were studied.The results showed that the surface of NiCo₂S₄ in the shape of flower spheres was regularly covered with thin sheets of CuO,and the electromagnetic wave absorption performance of NiCo₂S₄@CuO composites was enhanced and then weakened with the increase of the mass ratio of NiCo₂S₄.When the addition amount of NiCo₂S₄ is 0.1 g,the composite obtains the minimum reflection value of-34.2 GHz at a frequency of 9.6 GHz at a thickness of 2.5 mm,while the maximum effective absorption bandwidth of 4.64 GHz is obtained when the matched thickness is only 1.7 mm.（3）NiCo₂S₄/carbon microsphere composites were obtained using Ni（NO₃）₂·6 H₂O,Co（NO₃）₂·6 H₂O,C₂H₅NS and C₆H₁₂O₆ as raw materials and was prepared through the high temperature calcination method and hydrothermal method.The influences of raw material mass ratio and microscopic morphology on the electromagnetic wave absorption properties of the composites were researched.The results indicated that the granular NiCo₂S₄ modified on the surface of the carbon microspheres was beneficial to modulate the impedance matching properties of the material and introduced a large amount of interfacial polarization.The electromagnetic wave absorption properties of NiCo₂S₄/carbon microsphere composites were enhanced and then weakened with the increase of the mass ratio of carbon microspheres.When the addition amount of carbon microspheres is 0.15 g,the composite obtains a minimum reflection value of-47.4 GHz at a frequency of 16.96 GHz at a thickness of 1.45 mm,while the maximum effective absorption bandwidth of 4.64 GHz is obtained when the matched thickness is only 1.6mm.Figures[30]Tables[5]References[102]...