Synthesis and Magnetic Characterization of Cu Substituted Barium Hexaferrites

Tuning the Properties of Ba-M Hexaferrite BaFe11.5Co0.5O19: A Road Towards Diverse Applications

The development of hexaferrite nanoparticles is scrutinized as potential sorbents for the removal of chromium (Cr) ions from aqueous chromium-containing solutions in a batch adsorption experiment. The transition metal Co doped BaFe12O19 hexaferrite compounds (BHF) have been synthesized successfully via citrate auto combustion technique. The structure, surface morphology and magnetic properties of the samples were studied. X-ray diffraction pattern ratifies the existence of hexagonal phase as a main phase for the prepared samples. The average crystallite sizes are found in the range of 47–49 nm. The high-resolution transmission electron microscopy (HRTEM), as well as the Fourier, transform infrared spectrophotometry results confirm an M-type hexagonal structure existing. The χ-T indicates the temperature-dependent ferromagnetic behavior of BHF nanoparticles. The derivative shows a single transition temperature Tc at 698 °C, and 710 °C for BHF and BCHF respectively. The prepared samples are utilized as an adsorbent for the removal of Cr (VI) from the aqueous solution. The maximum adsorption capacity (qm) of Cr (VI) on the nano hexaferrite is higher than that of various other adsorbents testified in the literature. The pseudo-second-order kinetic model gives a better fit to the experimental data.

State-of-art of silver and gold nanoparticles synthesis routes, characterization and applications: a review

To date, the noble metal-based nanoparticles have been used in every field of life. The Au and Ag nanoparticles (NPs) have been fabricated employing different techniques to tune the properties. In this study, the methodologies developed and adopted for the fabrication of Au and Ag have been discussed, which include physical, chemical and biological routes. The Au and Ag characteristics (morphology, size, shape) along with advantages and disadvantages are discussed. The Au and Ag NPs catalytic and biomedical applications are discussed. For the Ag and Au NPs characterization, SEM (scanning electron microscope), TEM (transmission electron microscope), FTIR (Fourier transform infra-red spectroscopy), XRD (X-rays diffraction) and DLS (dynamic light scattering) techniques are employed. The properties of Au and Ag NPs found dependent to synthesis approach, i.e., the size, shape and morphologies, which showed a promising Catalytic, drug delivery and antimicrobial agent applications. The review is a comprehensive study for the comparison of Au and Ag NPs synthesis, properties and applications in different fields.

Magnetic Properties and Morphology Copper-Substituted Barium Hexaferrites from Sol-Gel Auto-Combustion Synthesis

The copper (Cu) substitution in barium hexaferrite (BaFe₁₂O₁₉) crystals from the sol-gel auto-combustion synthesis is demonstrated as a cost-effective pathway to achieve alterable magnetic properties. Subsequent heat treatments at 450 °C and 1050 °C result in irregularly shaped nanoparticles characterized as the M-type BaFe₁₂O₁₉ with the secondary phase of hematite (α-Fe₂O₃). Despite the mixed phase, the substantial coercivity of 2626 Oe and magnetization as high as 74.8 emu/g are obtained in this undoped ferrite. The copper (Cu) doing strongly affects morphology and magnetic properties of BaFe_12−xCu_xO₁₉ (x = 0.1, 0.3, and 0.5). The majority of particles become microrods for x = 0.1 and microplates in the case of x = 0.3 and 0.5. The coercivity and magnetization tend to reduce as Cu²⁺ increasingly substitutes Fe³⁺. From these findings, magnetic properties for various applications in microwave absorbers, recording media, electrodes, and permanent magnets can be tailored by the partial substitution in hexaferrite crystals.

Loading Effect of Sol-Gel Derived Barium Hexaferrite on Magnetic Polymer Composites

Solution–processing methods were investigated as viable alternatives to produce the polymer-bonded barium hexaferrite (BaM). BaM powders were first synthesized by using the sol-gel auto-combustion method. While the ignition period in two synthesis batches varied, the morphology of hexagonal microplates and nanorods, as well as magnetic properties, were reproduced. To prepare magnetic polymer composites, these BaM powders were then incorporated into the acrylonitrile-butadiene-styrene (ABS) matrix with a weight ratio of 80:20, 70:30, and 60:40 by using the solution casting method. Magnetizations were linearly decreased with a reduction in ferrite loading. Compared to the BaM loose powders and pressed pellet, both remanent and saturation magnetizations were lower and gave rise to comparable values of the squareness. The squareness around 0.5 of BaM samples and their composites revealed the isotropic alignment. Interestingly, the coercivity was significantly increased from 1727–1776 Oe in loose BaM powders to 1874–2052 Oe for the BaM-ABS composites. These composites have potential to be implemented in the additive manufacturing of rare-earth-free magnets.

Enhanced photocatalytic activity against crystal violet dye of Co and In doped ZnO thin films grown on PEI flexible substrate under UV and sunlight irradiations

This work is focused on the photocatalytic activities of undoped ZnO, Co (1%) doped ZnO (CZO) and In (1%) doped ZnO (IZO) thin films grown on flexible PEI (Polyetherimide) substrate by spray pyrolysis. The photodegradation of crystal violet dye was investigated under UV and sunlight irradiations. Doping and excitation energy effects on photocatalytic efficiencies are discussed. All ZnO thin films show high photocatalytic efficiency up to 80% under either UV or sunlight irradiations for 210 min. However, CZO has the higher photocatalytic performance under UV irradiation. While, the photodegradation efficiency of IZO was enhanced under sunlight irradiation due to the narrowing of its optical gap. These results are discussed based on structural, morphological and optical investigations. The photocatalytic stability of ZnO films was studied as well. So, after three photocatalysis cycles, all ZnO thin films still effective. The obtained results are promising for the use of doped ZnO/PEI as talented photocatalysts for applications in large surfaces with various geometries for photodegradation of hazardous pollutants.