Johari, Mohd Hilmi; Ismail, Ismayadi; Azis, Rabaah Syahidah; Tim, Chan Kar; Nafis, Nur Biha Mohamed; Ertugrul, Mehmet; Karakaş, Ibrahim Hakki

This study investigates the synthesis, microstructural characteristics, magnetic properties, and electromagnetic wave absorption performance of nickel ferrite (NiFe2O4) composites reinforced with multi-walled carbon nanotubes (MWCNTs) synthesized via the microwave-assisted combustion (MAC) method. X-ray diffraction (XRD) analysis confirmed the desired structure of NiFe2O4 and the successful integration of MWCNTs within the NiFe2O4 matrix. Field emission scanning electron microscopy (FESEM) analysis revealed the entanglement of MWCNTs and their significant impact on hindering particle growth, resulting in a finer particle structure. The reduction in average particle size from 1.317 µm for pure NiFe2O4 to 0.436 µm for NiFe2O4 with 2wt% MWCNT, representing approximately a 66.89% reduction, significantly demonstrates the effectiveness of MWCNTs in limiting particle growth and promoting a more refined particle structure. Magnetic property analyses showed a nuanced interplay between MWCNT concentration and composite behaviour, with the saturation magnetization (Ms) exhibiting substantial enhancement in the NiFe2O4/2wt%MWCNT composite, indicative of effective alignment of magnetic moments. However, a subsequent decrease in Ms at higher MWCNT concentrations (4wt% and 6wt%) suggested potential dilution effects and disruptions in magnetic interactions within the composite. Electromagnetic wave absorption investigations revealed NiFe2O4/4wt%MWCNT as a highly efficient absorber in the Ku-band, with superior impedance matching and a high attenuation constant. The reflection loss (RL) reached a maximum of –17.58 dB at 12.78 GHz, signifying absorption of more than 99% of the incident EM wave in the microwave range. The favourable impedance matching and high attenuation constant contributed to the superior performance of NiFe2O4/4wt%MWCNT compared to pure NiFe2O4 and MWCNT. These findings suggest the potential of NiFe2O4/MWCNT composites for applications in telecommunications, aerospace, and electronics, with opportunities for further optimization and investigation into long-term stability and durability under varying environmental conditions.

AtıfScopus1·WoS2·OpenAlex1

İncele

Karakaş, Ibrahim Hakki; Karcioğlu Karakaş, Zeynep

In this study, the effects on the photocatalytic activities of particles after heat treatment has been applied to cobalt ferrite nanoparticles produced by microwave-assisted combustion method were observed. The heat treatment applied to the samples was produced with only the microwave effect, at temperatures ranging from 300 to 1000°C. Thermogravimetric analysis was performed on the precursor sample in air atmosphere. During this analysis, the gases released up to 1200°C were identified with a Fourier-transform infrared (FTIR) spectrometer integrated into a thermogravimetric analysis system. Then, the cobalt ferrite nanoparticles produced with heat treatments applied at various temperatures were used as a photocatalyst to remove the dyestuff content in synthetic wastewaters prepared by using Astrazon Red GTL textile dye by photocatalytic oxidation, and their photocatalytic activities were compared. In these experiments, the operational parameters for photocatalysis processes were applied as 400 rpm for stirring speed, 50 mg/L for initial contaminant concentration, 0.5 g/L for catalyst dosage, 25°C for temperature, and 4400 μW/cm2 for light intensity. As a result of the experiments, it was observed that the crystal structure of the cobalt ferrite nanoparticles produced with the increase of the applied heat treatment temperature improved significantly. The obtained data show a strong relationship between the structural properties of materials and their photocatalytic activities. In addition, it was determined that the dyestuff in the solution was completely degraded in the experiments, and it was determined that all processes were compatible with the pseudo-first-order kinetic model.

AtıfScopus4·WoS5·OpenAlex6

İncele

Karcioʇlu Karakaş, Zeynep; Boncukcuoʇlu, Recep; Karakaş, Ibrahim Hakki; Ertuʇrul, Mehmet

NiFe2O4nanoparticles were synthesized using the microwave assisted combustion method based on metal nitrate salts and urea. To remain of organic matters and to stabilize the particles, samples were thermally treated at various temperatures from 300-800 °C. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The heat treated samples show the reflection planes of (111), (220), (222), (311), (400), (422), (511), and (440) which perfectly confirm to a cubic spinel phase of NiFe2O4and no secondary phases were detected in the XRD patterns of the samples. The crystallite sizes calculated using the Debye-Scherrer formula were found to increase with the heat treatment temperature, from about 4 nm at 300 °C-85 nm at 800 °C. EDX results verify that the compositional mass rations were relevant, as expected from the synthesis. The micrographs of SEM and TEM showed that all of the samples have nano-crystalline behavior and particles indication cubic shape. Magnetization measurements were obtained at room temperature by using a VSM, which demonstrated that the all of the samples synthesized with heat treatment exhibited ferromagnetic behaviors.

AtıfScopus96·WoS86·OpenAlex95

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