Effect of low sintering temperature on the structural and magnetic properties of M-type strontium hexaferrite

A pure M-type strontium hexaferrite with nominal composition SrFe12O19 was prepared via modified conventional citrate precursor method. The basic idea of investigation was to improve the quality of hexagonal ferrite without high temperature sintering as these ferrites are generally known for high temperature sintering techniques. Thermogravimetric analysis (TGA/DTA) of powdered sample was carried out to identify the desired crystallization point suitable for the formation of M-phase. After dividing the sample into two equal parts, the prepared sample was sintered at two different temperatures, 800˚C and 910˚C. The properties of the material were investigated via using important characterization techniques, XRD, FESEM, FTIR, Raman spectroscopy (RS) and VSM respectively. The XRD confirmed the formation of M-phase along with some impurities of Fe2O3 and these results were strongly supported via both FTIR and RS. On increasing the sintering temperature, the average crystallite size was found to increase from 25nm to 33nm. The FESEM analysis confirmed the formation of densely packed grains some hexagonal platelets along with agglomerates. The magnetic parameters saturation magnetization (Ms), magnetic coericivity (Hc) and squarenes ratio (SQR) were investigated by using VSM. The value of Ms for ferrite sample sintered at 910˚C was found to be 92emu/g but at the same time the Hc value was found in the range of few hundreds of Oestered. This kind of behavior was due to the smaller grain size and the presence of impurity phase which was totally against the nature strontium hexaferrite. Such properties of M-type hexagonal ferrite was found very rare and procured to be an excellent candidate for switching devices, recording media, high frequency applications and many more.

Performance Enhancement of Metamaterial Loaded Micro Strip Patch Antenna Design Using Gallium Doped Ba-Sr Hexagonal Ferrite as Substrate Material for X-band Applications

An experimental study of microstrip patch antenna designed and fabricated on FR4 epoxy substrate is presented. Further a performance comparison of designed antenna is made with proposed design using Gallium doped Ba-Sr hexagonal ferrite substrate. Microstrip feed line is used for inputting the signal to antenna. The whole simulation is done on HFSS simulator (version 13.0).The center frequency for proposed antenna is 10GHz and is optimized for significant performance parameters viz return loss, bandwidth, VSWR and gain. It was observed that the designed antenna provides better results with ferrite substrate as compared to FR4 epoxy substrate showing -10db broad bandwidth of 4.2GHz in the frequency region 8.2GHz to 12.4GHz. Although, the results of other parameters like return loss, VSWR and gain are found to be optimum with FR4 substrate as compared to mentioned ferrite substrate. The prototype of proposed antenna with FR4 epoxy substrate is fabricated and tested to attain the experimental results. The measured results are found to be better than simulated results. Thus the proposed antenna structure can be considered suitable for microwave communication application in X-band.

Bandwidth Enhancement of Cross-Shaped Fractal Antenna Using Lanthanum Doped Ba-Sr Hexagonal Ferrite As Substrate Material For X-Band Applications

This paper analyzes and compares the performance of a proposed cross-shaped fractal antenna design with two different substrate materials FR4 epoxy and lanthanum doped Ba-Sr hexagonal ferrite in X-band, where the lanthanum doped Ba-Sr hexagonal ferrite substrate is synthesized based on solid-state reaction method. The proposed antenna design is simulated using HFSS (High frequency structure simulator) version 15. The antenna is intended to work at 10 GHz frequency and involves four iterations. The antenna design is optimized for significant performance parameters viz. return loss, bandwidth, and gain. It provides better results with ferrite substrate as compared to FR4 epoxy substrate and provides − 10 dB broad bandwidth in three frequency regions 6.2969-6.4 GHz, 7.8702-9.44 GHz, and 9.68-9.7746 GHz. The prototype of proposed antenna with FR4 epoxy substrate is fabricated and tested to attain experimental results. The measured results are in good liaison with simulated results. This antenna structure can be considered suitable for RADAR, satellite, microwave communication, and weather forecasting applications in X-Band.

Dominating the Structural, Microstructural and Magnetic Features of Li+ Substituted Strontium Hexaferrite (Sr1-xLi2xFe12O19)

Lithium ion substituted hexagonal strontium ferrite (Sr1-xLi2xFe12O19, where x= 0.1, 0.2, and 0.3) powders have been felicitously fabricated using tartrate precursor scheme. The impact of the Li+ content, as well as the annealing temperature on the phase evolution, microstructure and magnetic performance, was commanded by X-ray diffraction profile (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). Single phase hexagonal ferrite was consummated at a Li+ ratio of 0.2 and different annealing temperatures, from 1000 to 1200oC for 2h. An impurity α-Fe2O3 phase was noted at a high Li+ concentration of 0.4 and 0.6 at all temperatures. The crystallo-aspects characteristics were altered with Li+ content and annealing temperature. The microstructure of pure hexagonal ferrite sample visualized platelet like structure. A fine spherical shape displayed with platelet shape by enhancing the Li+ content up to 0.4 and 0.6. EDX analysis emphasized Fe, Sr, O, and Li atoms spread between the plate and spherical shapes. Good saturation magnetization (Ms=60.88 emu/g) was realized for Li+ content of 0.2 as the results of increasing the thickness of the nanoplatelet structure.