Multiphase polymer-derived ceramics have the advantages of thermal stability and adjustable dielectric properties,which exhibit significant potential for use in high-temperature microwave absorbing materials.Herein,Co...Multiphase polymer-derived ceramics have the advantages of thermal stability and adjustable dielectric properties,which exhibit significant potential for use in high-temperature microwave absorbing materials.Herein,Co-containing polymer-derived SiCN(Co-SiCN)ceramics were successfully synthesized by the physical mixing of zeolitic imidazolate framework(ZIF)-67 and polysilazane precursors and subsequent pyrolysis.The phase and chemical compositions,microstructures,dielectric properties,electromagnetic wave absorption(EWA)performance,and mechanism of the ceramics were investigated.The results showed that the introduction of ZIF-67 promoted the in situ formation of dielectric loss phases,including SiC nanocrystals,CoSi nanocrystals,and free carbon.The phase composition can be regulated by controlling the pyrolysis temperature to achieve ideal EWA properties.The Co-SiCN ceramic pyrolyzed at 1500℃demonstrated excellent EWA performance,with a maximum effective absorption band(EAB_(max))of 3.0 GHz at an ultralow thickness of 1.05 mm and minimum reflection loss(RL_(min))of-46.4 dB at a low frequency of 6 GHz.Compared with other reported SiCN-based ceramics containing magnetic metals,the ceramics prepared in this study stand out because of their low RL and high EAB at low thicknesses.The superior microwave absorption performance of the Co-SiCN ceramics is attributed to the heterointerface polarization,and impedance matching induced by the synergistic effects of their co-existing electromagnetic transparent/absorption phases.This study provides new insights into the development of high-performance SiCNbased microwave absorbers.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.62071239,52102361)the Natural Science Foundation of Jiangsu Province(No.BK20200827)+1 种基金the National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering(No.JCKYS2022LD2)the Startup Foundation for Introducing Talent of NUIST(No.2020r025)。
文摘Multiphase polymer-derived ceramics have the advantages of thermal stability and adjustable dielectric properties,which exhibit significant potential for use in high-temperature microwave absorbing materials.Herein,Co-containing polymer-derived SiCN(Co-SiCN)ceramics were successfully synthesized by the physical mixing of zeolitic imidazolate framework(ZIF)-67 and polysilazane precursors and subsequent pyrolysis.The phase and chemical compositions,microstructures,dielectric properties,electromagnetic wave absorption(EWA)performance,and mechanism of the ceramics were investigated.The results showed that the introduction of ZIF-67 promoted the in situ formation of dielectric loss phases,including SiC nanocrystals,CoSi nanocrystals,and free carbon.The phase composition can be regulated by controlling the pyrolysis temperature to achieve ideal EWA properties.The Co-SiCN ceramic pyrolyzed at 1500℃demonstrated excellent EWA performance,with a maximum effective absorption band(EAB_(max))of 3.0 GHz at an ultralow thickness of 1.05 mm and minimum reflection loss(RL_(min))of-46.4 dB at a low frequency of 6 GHz.Compared with other reported SiCN-based ceramics containing magnetic metals,the ceramics prepared in this study stand out because of their low RL and high EAB at low thicknesses.The superior microwave absorption performance of the Co-SiCN ceramics is attributed to the heterointerface polarization,and impedance matching induced by the synergistic effects of their co-existing electromagnetic transparent/absorption phases.This study provides new insights into the development of high-performance SiCNbased microwave absorbers.
