Teber, Ahmet; Sarac, Mehmet F.

The effect of Yttrium Substitution on Co0.5Ni0.5YxFe2- xO4 (0.0 ≤ x ≤ 1.0) Ferrites as Microwave Absorbers was investigated to include structural, magnetic, dielectric and X-band absorption properties. The main objective of this work is to enhance microwave absorption properties of materials with interesting dielectric/magnetic behaviors by doping rare earth element of Yttrium based on transition metals. The hydrothermal method was used to create Yttrium (Y) substituted nanoparticles, and the effects of Y-ion substitution on the characteristics, structural, magnetic features were examined by XRD, FT-IR, SEM-EDS, TEM-SAED, and VSM, respectively. Electromagnetic properties were obtained from microwave scattering parameters measured via a metal-backed transmission line and Nicholson-Ross Weir techniques using a vector network analyzer (VNA) in conjunction with an X-band waveguide set. Return loss (RL) values of the samples were obtained from the electromagnetic constitutive parameters (permittivity and permeability). According to the XRD measurements, hexagonal crystal structure of ferrite and YFeO3 as secondary phase nanocrystal sizes are between 11 and 67 nm. Refined structural parameters using Rietveld analysis are carried out using the TOPAS refinement program. A good match was observed between the diffraction patterns obtained and calculated by Rietveld analysis. Moreover, the morphological analyses indicate that the relatively small spherical structures of Ni-Co ferrites particles can be seen to change from spherical to hexagonal-shaped with increasing yttrium concentration. The results of the FT-IR study show that the spinel structure has formed as predicted because the expected range of absorption bands is present. According to magnetic measurements, the coercivity (Hc) results show a modest increase in porosity as the Y-content rises. The results revealed that the minimum RL value and bandwidth vary significantly with the amount of Yttrium in the mixture, indicating that the obtained structures will be useful for broadband microwave applications.

AtıfScopus10·WoS11·OpenAlex12

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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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