Study On Synthesis And Characterization Of Polyaniline/doped Barium Ferrite Nanocomposite Materials

BaFe_x(Ti_0.5Mn_0.5)_12-xO₁₉(X=8,9,10,11,12) barium ferrite nanoparticles were synthesized by sol-gel method using nitrate and citric acid as the main materials. XRD,TEM and VSM were used to study the phase composition, microcosmic morphology and magnetic properties of the nanoparticles, respectively. The results showed that all the synthesized particles were barium ferrite nanocrystal with hexa angles growing completely which had good particle dispersivity and the average diameter of these particles was 50～80nm. As X increasing, saturation magnetizationδ_s and remanent magnetizationδ_r increased first and then decreased, while coercitivity H_c kept increasing gradually at all times. When the temperature reached to 900℃and X equaled to 9,δ_s presented the max value 35.0emu·g^-1,and 900℃, X equaled to 11, H_c reached to the max value 3.97 kOe.In this paper ,we chose barium ferrite BaFex(Ti_0.5Mn_0.5)_12-xO₁₉(X=9,10,11) particles with small diameter and good magnetity to prepare polyaniline/BaFex(Ti_0.5Mn_0.5)_12-xO₁₉ composite particles according to the in-situ polymerization method and the barium ferrite quality ratio occupyied 45% and 30% in the composite particles. XRD,TEM and SEM data showed that there was typical peak of polyaniline in the composite particles, and the average diameter reduced to 35～50nm after coating compared to 50～80nm before coating, also the agglomeration weakened distinctly while the dispersibility reinforced. FITR was used to measure the infrared spectra of the composite particles. The spectra contained all the absorption peak of polyaniline and typical absorption peak of BaFe_x(Ti_0.5Mn_0.5)_12-xO₁₉ particle at 579cm^-1 and 507cm^-1.The results supported that chemical bonds existed between polyaniline and BaFex(Ti_0.5Mn_0.5)_12-xO₁₉ particle and the synthesis was successful. The magnetic test data showed that magnetic parameter of the synthesized simple decreased as the barium ferrite content decreased. Therefore, the content of barium ferrite was a significant factor on the influence of magnetity. When X equaled to 10 and the BaFex(Ti_0.5Mn_0.5)_12-xO₁₉ particle content reached to 45%,the composite particleδ_s got to the max value 20.1emu·g^-1,and X equaled to 11, the BaFex(Ti_0.5Mn_0.5)_12-xO₁₉ particle content reached to 30%, H_c of the composite particle got to the max value 3.22kOe。Mixed the composite particle polyaniline / BaFe_x(Ti_0.5Mn_0.5)_12-xO₁₉ and paraffine powder make sure that the particle and the powder quality ratio was 2:3.Then tested the mixture complex dielectric constant and complex permeability in the range of 2～18GHz.It was analyzed that the mixture dielectric loss angle tangent value tanδ_e=ε_r″/ε_r^′decreased and magnetism loss angle tangent value tanδ_m=μ_r^″/μ^′fluctated when the frequency increased, and the extremum of tanδ_e and tanδ_m appeared at 9GHz,15GHz and 6GHz,12GHz respectively. Applied theε=ε′-jε″andμ=μ′-jμ″to the equation ,it could be get the reflectivity R, when below -10dB bandwidth exceeded to 10GHz and X equaled to 9, the reflectivity of the composites containing 45% barium ferrite was-16dB,which was good absorbing materials.