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    Impact of Eu3+ ion substitution on structural, magnetic and microwave traits of Ni-Cu-Zn spinel ferrites
    (Elsevier Sci Ltd, 2020) Almessiere, M. A.; Slimani, Yassine; Güngüneş, Hakan; Kostishyn, Vladimir G.; Trukhanov, Sergei; Trukhanov, Alex V.; Baykal, Abdulhadi
    Partially europium (Eu) substituted Ni0.4Cu0.2Zn0.4EuxFe2-xO4(0.0 <= x <= 0.10) nanostructured spinel ferrites (NSFs) were produced by sol-gel auto-combustion strategy. The XRD analyses verified the existence of the single-phase composition in all the investigated samples. The Mossbauer spectra were used to estimate the values of the line-width disparity, isomeric shift (IS), quadrupole splitting, and hyperfine magnetic field (HMF). The values of HMF of the A and B sites decreased with the rise in Eu substitutions. The paramagnetic contribution of the NSFs increased with the rise in Eu3+ contents. The S-parameters of the proposed NSFs were measured using co-axial method. The frequency dispersions of the permittivity and permeability were utilized to determine the reflection losses in the 1-20 GHz frequency range. The occurrences of the natural ferromagnetic resonance (NFMR) enabled substantial absorption of the electromagnetic energy ranged from 2.5 to 9.5 GHz. There was established a strong correlation between the level of chemical substitution (x) and amplitude-frequency characteristics of the studied spinel ferrites was established. Furthermore, the increase of Eu substitution strongly influenced the frequency characteristics of the NSFs. Anomalous changing of the resonant amplitude (more than 4 times) was shown. This can be explained by the appearance of indirect exchange interactions between Fe3+ (3 d(5)) and Eu3+ (4f(6)) electronic shells. Results revealed a potential for practical applications of such kinds of materials in functional radio electronic devices.
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    Magnetic Attributes of NiFe2O4 Nanoparticles: Influence of Dysprosium Ions (Dy3+) Substitution
    (Mdpi, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Ali, Sadaqat; Manikandan, Ayyar; Ercan, İsmail; Trukhanov, Alex V.
    This paper reports the influence of dysprosium ion (Dy3+) substitution on the structural and magnetic properties of NiDyxFe2-xO4 (0.0 <= x <= 0.1) nanoparticles (NPs) prepared using a hydrothermal method. The structure and morphology of the as-synthesized NPs were characterized via X-ray diffraction (XRD), scanning and transmission electron microscope (SEM, and TEM) analyses. Fe-57 Mossbauer spectra were recorded to determine the Dy3+ content dependent variation in the line width, isomer shift, quadrupole splitting, and hyperfine magnetic fields. Furthermore, the magnetic properties of the prepared NPs were also investigated by zero-field cooled (ZFC) and field cooled (FC) magnetizations and AC susceptibility measurements. The M-ZFC (T) results showed a blocking temperature (T-B). Below T-B, the products behave as ferromagnetic (FM) and act superparamagnetic (SPM) above T-B. The M-FC (T) curves indicated the existence of super-spin glass (SSG) behavior below T-s (spin-glass freezing temperature). The AC susceptibility measurements confirmed the existence of the two transition temperatures (i.e., T-B and T-s). Numerous models, e.g., Neel-Arrhenius (N-A), Vogel-Fulcher (V-F), and critical slowing down (CSD), were used to investigate the dynamics of the systems. It was found that the Dy substitution enhanced the magnetic interactions.
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    Manganese/yttrium codoped strontium nanohexaferrites: Evaluation of magnetic susceptibility and mossbauer spectra
    (MDPI AG, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Baykal, Abdulhadi; Trukhanov, Sergei Valentinovich; Trukhanov, Alex V.
    Abstract: Manganese (Mn)- and yttrium (Y)-substituted Sr-nanohexaferrites (MYSNHFs) of composition Sr1_xMnxFe12_xYxO19 (with 0.0 ? x ? 0.5) were prepared by citrate sol-gel autocombustion method. As-prepared MYSNHFs were characterized via diverse analytical techniques to determine the influence of Mn and Y cosubstitution on their microstructures and magnetic properties. 57Fe Mössbauer spectra of the MYSNHFs were used to evaluate the variation in the line width, isomer shift, quadrupole splitting, and hyperfine magnetic field values. It was shown that the dopant ions could preferentially occupy the 12k, 4f2, and 2b sites. Furthermore, the observed shift in the blocking temperatures of the studied MYSNHFs towards lower values with rising Mn2+ and Y3+ contents was attributed to the overall particles size reduction. Meanwhile, the AC susceptibility of the proposed MYSNHFs revealed that the magnetic interactions were weakened with the increase in dopant contents which was ascribed to the replacement of both Sr2+ and Fe3+ ions by the Mn2+ and Y3+ dopants.
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    Structure, Mössbauer and AC susceptibility of strontium nanohexaferrites: Effect of vanadium ions doping
    (Elsevier Ltd, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Güngüneş, Hakan; Baykal, Abdulhadi; Alhamed, Nada A.; Trukhanov, Alex V.; Trukhanov, Sergei Valentinovich
    This study contains information about the effect of V3+ vanadium doping on structural, morphological and magnetic properties of SrFe12-xVxO19 (x?=?0.00, 0.02, 0.04, 0.06, 0.08, 0.10) nanohexaferrites. Samples have been prepared via citrate sol-gel method and characterized. XRD and SEM analyses revealed the formation of M-type nanohexaferrites, wherein the particle size remained unaltered with the increase in vanadium contents. Mossbauer spectra disclosed the preferred occupation of V3+ ions at 4f1 tetrahedral site. Zero field (ZFC) and field cooled (FC) magnetization data in the temperature range of 2–400?K did not exhibit any blocking temperature, indicating mostly the ferromagnetic long-range ordering for the studied nanohexaferrites. Moreover, at low temperatures a spin glass behavior was observed. The ac-susceptibility showed a weakening in the Fe3+ - O2? - Fe3+ indirect exchange interactions with the increase in V3+ contents. Magnetic properties are argued in terms of the empirical rules of indirect exchange interactions taking into account the substitution of Fe3+ cations by V3+ ones in the preferred sites.