Preparation And Microwave Absorption Properties Of Doped Zinc Oxide

Nowadays, with the development of electronic industry, people's living standards keep enhancing, and various electronic devices are emerging. Subsequently electromagnetic wave pollution is also increasing day by day, greatly threatening people's health. Besides, along with military and information security technology's fast development, applications of microwave absorbing material has become more and more, therefore, and research of such materials is gaining more and more attention. ZnO receives much extensive research due to its good characteristic and easy fabrication.In this paper, transition metals are doped into the zinc oxide by the decomposition of acetate solid solutions, to fabricate doped zinc oxide with sub-micron rod structure, for investigating the doped material's application perspective in microwave absorption. Five sub-micron rod structure materials are made through water-bath method: Mn, Ni, Co, Mn/Ni and Mn/Co doped ZnO. XRD, EDS, SEM are used to analyze their constitution and profile, and VSM is used to test its static magnetism, and vector network analyzer for electromagnetic characteristics using co-axial method. Relations between electromagnetic characteristics and doping concentrations are analyzed and compared. The obtained characteristics are applied to simulate the microwave reflectivity with material respectively. Relations between reflectivities of doped ZnO are also analyzed.The results indicate that microwave absorbing composite which uses doped zinc oxide as absorbent and uses paraffin as base shows an excellent performance in microwave absorbing. Main results of experiment are as follow:(1) Mn, Ni, Co, Mn/Ni, Mn/Co doped ZnO does not have difference morphology to normal ZnO. A small amount of doping will not change the crystal structure of ZnO. (2) Static magnetism analysis of doped ZnO shows very weak magnetism, which means doping does not bring in magnetic loss as a microwave absorbing mechanism. (3) The results of electromagnetic parameters test show that doping can effectively improve the dielectric properties of zinc oxide. (4) Simulation results based on sample's permittivity show that transition matel doping can effectively improve the microwave absorbing of ZnO. Elements and concentration of doping both have important influence of ZnO's microwave absorbing properties. The max absorbing peak of Mn doped, Ni doped and Co doped ZnO reaches 80 dB(f=9.9 GHz),72.5 dB(f=11.6 GHz) and 65.4 dB(f=10 GHz) respectively. They act in relatively low, medium and high frequency zone respectively. It was found that the absorption reaches peak value at certain concentration, and higher or lower concentration does not yield better results.