Study On The Preparation And Absorption Performance Of The Co-based Coordination Polymers And Their Derivatives

With the rapid development of science and technology,people's living environment is fully filled with electromagnetic radiation.Absorbing materials will walk gradually into the people's vision,and then species are also increasing.However,it has been found that the application of cobalt-containing coordination polymers and their derivatives in absorbing materials is very rare.In this paper,cobalt-containing coordination polymers and their derivatives were successfully prepared by hydrothermal method and their absorbing properties were studied.The main contents are as follows:(1)Synthesis of cobalt and rare earth coordination polymers by hydrothermal method.The rare earths are lanthanum,cerium,praseodymium,neodymium,samarium,europium,gadolinium,terbium.S-XRD,P-XRD,SEM,EDS and FT-IR were used to characterize the morphologies,contents and structures.The results show that the structures of coordination polymers containing cobalt and rare earth are divided into two different groups,including the cobalt and lanthanum(and also cerium,praseodymium,neodymium,samarium,europium)coordination polymers as new single crystal structures.The microwave absorption activities of the samples have been performed.The results showed that cobalt and rare earth coordination polymers have microwave absorption capability.(2)A coordination polymer of DyCo(Pydc)3(H2O)3(1;Pydc: 2,3-pyridinedicarboxylic acid)was designed by mild hydrothermal synthesis.Then it was used as a precursor to produce DyCoO3,2 via heating at 700? in an oven.SEM,EDS and XRD were used to characterize the morphologies,contents and phases.The microwave absorption activities of the precursor and the perovskite oxide have been performed.The results showed that both have strong microwave absorption properties,and both of 3(Ni(OH)2/1)and 4(NiO/2)were designed by added with Ni to 1 and 2 to be optimized into composite materials leading to the improved absorption performance.Expecially,the absorption performance of 4 was significantly improved especially in the high frequency band.when the frequency was 18 GHz,and the thickness of 6mm,the reflection loss was increased up to-36.68 dB.(3)The cobalt-containing coordination polymer was synthesized by hydrothermalmethod,and three different precursors were obtained by changing the amount of LiOH.The three precursors were calcined in air at 500? for 4h to obtain Co3O4 Nanotubes and nanosheets.The structure and morphology were characterized by XRD,SEM.And then the absorption performance of the samples were studied.The results show that the nanoporous Co3O4 has excellent microwave absorption properties.This excellent microwave performance not only comes from dielectric loss and impedance matching also comes from the geometrical effect.