Fabrication of Mg 1-X Zn X Fe 2 O 4 (where x = 0.2, 0.3, 0.4 and 0.5) samples using a conventional technique is reported. Oxides of magnesium, zinc and iron with purity of about 99.99% were mixed with distilled water in a milling machine for 12 hours. They were then filtered and presintered at 1250°C and sintered at 1350°C for 10 h in air. The phase and the crystal structure of the asprepared samples were identified using X-Ray Diffraction analysis (XRD). Hysteresis graph was evaluated using Vibrating Sample Magnetometer (VSM) to get the saturation magnetization (emu g −1 ) and coercivity (G) value. Atomic Force Microscope (AFM) was used to observe the surface morphology. The X-ray diffraction analysis showed major peak at plane (3 1 1) of the cubic structure for all the ferrites. The largest value of density achieved was 4.69 gcm −3 which was exhibited by sample with 0.5 mole fraction of zinc content. Highest saturation magnetization value (3.652emu g −1 ) was obtained for the 0.3 mole fraction of zinc content. A strong correlation between the saturation magnetization and zinc content was observed. We speculate that it is due to the Heisenberg superexchange interaction of magnetic Fe 3+ and non-magnetic Zn 2+ occupying the tetrahedral sites. The sample was used to induce electromagnetic (EM) waves in high operating frequency (5 MHz).

YBa2Cu3O7−δ (Y-123) bulk superconductors with the addition of (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 wt.%) SnO2 nanoparticles were synthesised via a thermal treatment method. The influence of SnO2 addition on the superconducting properties by means of critical temperature, Tc, AC susceptibility, phase formation and microstructures, including its elemental composition analysis, were studied. Sharp superconducting transition, ∆Tc, and diamagnetic transition were obtained for all SnO2-added samples. It was observed that sample x = 0.4 with a Y-123 phase percentage of 95.8% gives the highest Tc, smallest ∆Tc, and the sharpest diamagnetic transition in the normalised susceptibility curves. The microstructure also showed an excess of Sn precipitates on the sample’s surface at x = 0.8 and above. As such, the best superconducting properties were observed at x = 0.4 SnO2 addition inside the Y-123 host sample.

Colossal magnetoresistive (CMR) materials have been widely studied because of their huge potential in spintronic technology. An introduction of secondary phase to the manganite matrix is able to improve the low field magnetoresistance (LFMR). This method is favoured by recent research works as it requires a lower magnetic field compared to intrinsic magnetoresistance. Structural, magnetic properties and magnetotransport properties of polycrystalline (1-x) La0.67Ca0.33MnO3 (LCMO): x TiO2 composites where x = 0.00, 0.05, 0.10, 0.15 and 0.20 were investigated in this work. Polycrystalline La0.67Ca0.33MnO3 (LCMO) was synthesized via sol-gel method and pre-sintered at 800 °C before appending with nano-sized TiO2. All samples are in LCMO phase having an orthorhombic structure with space group Pnma. The crystal structural parameter is studied by using Rietveld refinement. As TiO2 content increases, the magnetization is getting higher as observed via vibrating sample magnetometer (VSM) analysis at room temperature. Magnetotransport properties of the pure LCMO sample have been studied from 80 – 220 K. The LFMR is enhanced as the temperature drops. The results have shown LCMO: TiO2 manganite composite is an excellent candidate for future magnetic sensors and memory devices.

No abstract

No abstract