Preparation And Electromagnetic Performance Of Polypyrrol/Strontium-Ferrite Composites

In this article,the Sr_1-xLa_xFe₁₂O₁₉?x=0,0.05,0.1,0.15 and 0.2?and Sr_0.95La_0.05Fe_12-yCoyO₁₉?x=0.1,0.2,0.3 and 0.4?ferrites were prepared by self-propagating method,and the PPy-Sr_0.95La_0.05Fe₁₂O₁₉ and PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ nanocomposites were synthesized by in situ polymerization method,respectively.And the obtained products were characterized by X-raydiffraction?XRD?,scanning electron microscopy?SEM?,fourier transformin frared?FT-IR?spectrometer,vibrating sample magnetometer?VSM?and the vector network analyzer.The influence of the property can be found when the molar ratio of Co²⁺ and La3+ ions has been changed in the strontium ferrites.The influence of the properties can also be found when the mass fraction of ferrites has been changed in the composites.?1?It can be seen from the XRD pattern that the Sr_1-xLa_xFe₁₂O₁₉,Sr_0.95La_0.05Fe_12-yCoyO₁₉,PPy-Sr_0.95La_0.05Fe₁₂O₁₉ composites and PPySr_0.95La_0.05Fe_11.8Co_0.2O₁₉ composites were obtained,respectively,which is similar with the results of the FT-IR.From the result of XRD,it can also be figured out that the particle sizes of the Sr_1-xLa_xFe₁₂O₁₉?x=0,0.05,0.1,0.15,0.2?and Sr_0.95La_0.05Fe_12-yCoyO₁₉?y=0.1,0.2,0.3,0.4?ferrites are 74.7nm,61.1nm,63.8nm,62.4nm,63.5nm,68.0nm,65.6nm,70.4nm and 65.3nm,respectively.?2?The SEM images show that the morphology of SrFe₁₂O₁₉ ferrites is in irregular shape.Most of SrFe₁₂O₁₉ ferrites like spherical,but a little of them like stick and flake.While the Sr_0.95La_0.05Fe₁₂O₁₉ and the Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ ferrites are most nearly spherical particles.And all those ferrites have a degree of reunion.The microstructure of PPy,PPy-Sr_0.95La_0.05Fe₁₂O₁₉ and PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ is nearly spherical and the grain are consistent.The structure of PPy,PPy-Sr_0.95La_0.05Fe₁₂O₁₉ and PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ is neat,but the particals have a certain reunion phenomenon.?3?The VSM results know that the Ms,Mr and Hc of Sr_0.95La_0.05Fe₁₂O₁₉ ferrites are 57.32emu/g,33.31emu/g and 6018 Oe,respectively,which are obvious higher than those of the SrFe₁₂O₁₉.While the La3+ ions droped into the lattice of the strontium ferrite,the magnetic parameters of Sr_0.95La_0.05Fe₁₂O₁₉ ferrites have been increased,and the Ms,Mr and Hc of Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ ferrites are 53.40emu/g,31.24emu/g and 4733 Oe,respectively.The Ms,Mr and Hc of PPy-Sr_0.95La_0.05Fe₁₂O₁₉ are 8.01emu/g,4.59emu/g and 6551 Oe,respectively,and the Ms,Mr and Hc of PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ composites are 14.57emu/g,7.81emu/g and 6068 Oe,respectively.?4?The result of vector network analyzer shows that the real part of permittivity??'?of Sr_1-xLa_xFe₁₂O₁₉ ferrites has maximum value when x=0.1,while the influence of La3+ ions content on the imaginary part of permittivity??''?and reflection loss?R?is not obvious.The R of Sr_1-xLa_xFe₁₂O₁₉ ferrites is between 0.16 dB and-0.43 dB.The maximum value of reflection loss of Sr_0.95La_0.05Fe₁₂O₁₉ ferrites is-0.43 dB when the frequency appears in 18 GHz.For the Sr_0.95La_0.05Fe_12-yCoyO₁₉ ferrites,the ?' and ?'' have maximum value when the value of y are 0.4 and 0.3,respectively.The ?'' of Sr_0.95La_0.05Fe_12-yCoyO₁₉ is between 0.08 to-0.35,while the content of the Co²⁺ ions has little influence on it.The R of the Sr_0.95La_0.05Fe11.6Co0.4O₁₉ ferrites has the minimum value when the frequency appears at 17.9GHz that is-0.2453 dB.For the PPy-Sr_0.95La_0.05Fe₁₂O₁₉ composites,when mass fraction of the Sr_0.95La_0.05Fe₁₂O₁₉ ferrites is 20%,the R has the minimum value that is-7.2dB at the frequency of 18.23 GHz.For the PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ composites,the ?' of the PPy-Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ composite achieved at the maximum value when mass fraction of the Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ ferrite is 10%.The maximum value of ?'' has been got when mass fraction of the Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ ferrites is 20%,while the content of Sr_0.95La_0.05Fe_11.8Co_0.2O₁₉ ferrites has little influence on it.The R has the minimum value at the influency of 18.14 GHz,which is-4.95 dB.