Titanate Ferrous Compounds Synthesis, Characterization And Microwave Absorbing Properties

As the key of stealthy technology,radar-absorbing material (RAM) has been paid more and more attention all over the world,it has being the hotpot in national defense field after the gulf-war. The primary goal of RAM research is to design and produce high-performance absorbent that can not only absorb electromagnetic energy,but also bear load,and so on. That is just the topic of the present dissertation.The ilmenite compound is a sort of inorganic function material,which behaves superior absorbing property in given electroconductibility and can be used as absorbent in stealthy technology,the study about it's absorbing property starts not long before.A great variety of possible methods that may synthesis ilmenite compounds had been tried to get a easy and practical way synthesizing studied samples,for example:high-temperature solid-state method;chemical co-precipitation method;sol-gel method. The sample composition was analyzed by means of TG and x-ray diffraction. The following conclusions can be drawn from the experiments:given conditions,the sample powder that has the same XRD data as the standard FeTiOa can be gotten when use any method mentioned above;the key in synthesis is to avoid the oxidation of Fe2+,so the whole process should performed under vacuum or neutral atmosphere,samples used by this study were prepared under nitrogen atmosphere;the heat-treated time and temperature have some influence on the sample powder,results show that the proper time and temperature is 120 minutes and 1100 respectively.Three series of absorbent powder samples were synthesized by the high-temperature solid-state method:the first is that Fe/Ti mol proportion in the material changes regularly;the other one is that different thuliums doped in the same absorbent;the last series is the absorbent was doped by different content thulium.The permittivity and permeability of the modified ilmenite absorbents were systematically measured. The relationship between the electromagnetic properties of the absorbent and composition and the kind,content of the doped thulium was explored. Furthermore,the absorbent's electroconductibility as the function of its permittivity andpermeability was also uncovered. The reflectance of the absorbents was calculated,and the effects of the preparation and the thickness on the absorbing ability were discussed. In a word,the prepared ilmenite absorbents are non-magnetic materials,at giventhickness used in applications,the single-layered absorbents have the minimal reflectivity of-50dB and maximal bandwidth of 5GHz.