Microwave adsorption of Sr(MnTi)(x)Fe(12-2x)O(19) particles

MnTi-substituted strontium ferrite particles of Sr(MnTi)(x)Fe(12-2x)O(19), (x = 0-2.0), were synthesized using the aqueous combustion method. The structural character and the thermal properties of the sol-gel were investigated using Fourier transform infrared spectroscopy and thermogravimetric analysis, and the effects of the chemical composition and annealing temperature on the crystalline structure, the magnetic properties, and the morphology of ZnTi-substituted strontium ferrite particles were studied using X-ray diffraction, vibrating sample magnetometer measurements, and high-resolution scanning electron microscopy. X-ray diffraction indicated that M-type and Y-type hexagonal phases coexist in Sr-ferrites annealed at 1000 C/2 h. However, a single phase of M-type hexagonal ferrite was obtained by heating the prepared powder at 1200 C/2 h. The saturation magnetization at 300 K was found to greatly increase from 43.7 emu/g in SrFe(12)O(19) ferrite to 59.0 emu/g in Sr(MnTi)o.5Fe(11)O(19) ferrite. In contrast, the intrinsic coercivity was found to rapidly decrease from 4.32 kC in SrFe(12)O(19) ferrite to 3.25 kG in Sr(MnTi)(0.5)Fe(11)O(19) ferrite. The composite specimens of Sr(MnTi)(x)Fe(12-2x)O(19) and thermal plastic resin showed wide-band microwave absorption due to reflection losses from -15.7 to -22.7 dB at frequencies between 18 and 40 GHz as observed by a high-frequency network analyzer.