Preparation And Performance Of Doped BaTiO₃Composite Absorbing Materials

It has been reported that barium titanate(BaTiO3) has a high dielectric constant andexcellent ferroelectric property, but single BaTiO3cannot meet requirement of absorbingmaterial "thin, light, wide, strong". Barium titanate was modified via the methods ofdoping, compounding and electroless plating in this project to improve the microwaveabsorbing property of barium titanate in the low frequency region(0-6000MHz).Thedetailed research methods and contents are as follows:(1)Barium titanate doped with Mn and Nd (Ba(1-x-y)MnxNdyTiO3) was prepared bysol-gel method and characterized by X-ray diffraction(XRD), energy dispersivespectrometer(EDS), and scanning electron microscope(SEM). Absorbing propertytesting results showed that the sample with x=0.05, y=0.05had a maximum microwaveabsorption(-17.90dB). The sample with x=0.05, y=0.07had the maximum bandwidth ofR<-5dB and the peak width was1191MHz.(2)The composites of BaTiO3/SrFe12O19were prepared by calcining the mixture ofNd doped BaTiO3gel precursor and SrFe12O19gel precursor at high temperature andcharacterized by XRD, EDS, and SEM. Magnetic performance analysis results showedthat when the content of barium titanate was10wt%, the sample had the largestsaturation magnetization(79.96emu g-1). Absorbing property testing results showed thatwhen the content of barium titanate was50wt%, the sample had a maximum waveabsorption (-12.70dB) at the frequency of5312.4MHz. (3)The composites of Nd doped BaTiO3and different mass percent of carbonnanotubes(CNTs) were prepared via hydro-thermal method and were characterized byXRD, EDS, and transmission electron microscope(TEM). Absorbing property testingresults showed that when the content of CNTs was7wt%, the composites had themaximum wave absorption (-13.5dB) at the frequency of4270.8MHz with a peak widthof520.8MHz(<-5dB).(4)Electroless plating Ni-Co on the surface of BaTiO3/CNTs composites wasperformed at different process parameters by using Tollens’ reagent assensitization-activator. The influence of temperature and pH value on the process ofeletroless plating and the microwave absorbing property was investigated. Absorbingproperty testing results showed that the sample with the temperature of60℃, the pHvalue of8had the maximum wave absorption (-32.9dB) at the frequency of5610.0MHz.The sample with the temperature of60℃, the pH value of9had the maximumbandwidth of R<-5dB and the peak width was1082MHz. At last, the reactionmechanism of palladium-free eletroless plating was analyzed.