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    Effect of annealing temperature on magnetic and mössbauer properties of ZnFe2O4 nanoparticles by sol-gel approach
    (Springer New York LLC, 2018) Amir, Md.; Güngüneş, Hakan; Baykal, Abdulhadi; Almessiere, Munirah Abdullah; Sözeri, Hüseyin; Ercan, İsmail; Sertkol, Murat; Asiri, Sarah Mousa; Manikandan, A.
    In this study, spinel ZnFe 2 O 4 nanoparticles (NPs) were synthesized by citrate sol-gel route using nickel nitrates, ferric nitrates and citric acid by annealing at 900, 1000, and 1100 ? C. We reported the structural and magnetic properties (including Mössbauer analysis) for anisotropy ZnFe 2 O 4 NPs annealed at different temperatures. Fourier transform infrared (FT-IR) and X-ray powder diffraction (XRD) were utilized to analyze the structural properties of magnetic nanoparticles (MNPs). Morphological features of resultant MNPs were examined by scanning electron microscopy (SEM). The observed XRD results displayed that the crystallite size increased from 38.60 to 49.28 nm with increasing the annealing temperature in a distinct linear trend. The enhancement of saturation magnetization of the uniaxial ZnFe 2 O 4 NPs was studied and varied from 1.28 to 1.66 emu/g as the annealing temperature increases. The Mössbauer spectra results show that ZnFe 2 O 4 ferrites were paramagnetic in nature at room temperature (RT). © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
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    Hydrothermal synthesis of CoyZnyMn1-2yFe2O4 nanoferrites: Magneto-optical investigation
    (Elsevier Ltd, 2018) Asiri, Sarah Mousa; Sertkol, Murat; Güner, Sadık; Güngüneş, Hakan; Mujasam Batoo, Khalid; Saleh, Tawfik A.; Sözeri, Hüseyin; Almessiere, Munirah Abdullah; Manikandan, A.; Baykal, Abdulhadi
    Manganese ferrites nanoparticles (NPs) substituted with both Co2+ and Zn2+ simultaneously (CoyZnyMn1-2yFe2O4 NPs for y=0.0 to 0.5), have been produced by hydrothermal approach. The substitution with both Co2+ and Zn2+ ions on the structure, spectroscopic and magneto-optical properties of nanocrystalline MnFe2O4 spinel ferrites have been analyzed in detail. The formation of spinel phase and structural changes induced by Co2+ and Zn2+ ions substitutions were confirmed by X-ray diffraction studies. Rietveld refinement revealed the cubic spinel phase for all products (minor amount of Fe2O3). Lattice constant and crystallite size were found to decrease from 8.478 to 8.370 Å and from 14.68 to 8.22 nm, respectively with increasing substitution of Co2+ and Zn2+ ions. HR-SEM and HR-TEM micrographs revealed the high homogeneity cubic structure of samples. The hyperfine magnetic field values for all products after Mn2+, Zn2+ and Co2+ ions substitution were determined by Mössbauer analysis. The estimated optical Eg (Energy band gap) values are in the range of 1.41–1.54 eV for the samples. The smaller Eg values are mainly attributed to greater particle size and decreasing quantum confinement effect. © 2017 Elsevier Ltd and Techna Group S.r.l.
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    Magnetic properties and cation distribution of bimetallic (Mn–Co) doped NiFe2O4 nanoparticles
    (Springer New York LLC, 2017) Baykal, Abdulhadi; Eryiğit, Ş. Ş.; Amir, Md.; Güngüneş, Hakan; Sözeri, Hüseyin; Shirsath, Sagar E.; Sertkol, Murat; Asiri, Sarah Mousa
    Nickel ferrite (NiFe2O4), an inverse spinel crystal structure and a soft transition metal oxide, contemplated as a good magnetic semiconducting material with low coercivity and saturation magnetization (M s). In this study, Ni1?2xMnxCoxFe2O4 (0.0???x???0.5) nanoparticles were synthesized by the microwave assisted approach with citric acid as fuel. The effect of both cobalt and manganese substitution on the morphological, structural, and magnetic properties of the NiFe2O4 nanoparticles were studied. X-ray powder diffraction patterns confirm their complete conversion to NiFe2O4 crystal phase and the increase in lattice constant provides evidence for the effect of both Co and Mn substitution. SEM images divulge the nano-size of the prepared products with speck morphology. Magnetic properties of the final products were evaluated using Vibrating Sample Magnetometer and 57Fe Mössbauer spectroscopy. The results from both analyses suggested the M s and coercive field of NiFe2O4 NPs increases as the concentration of Co and Mn increase and Ms getting closer to the bulk value.
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    Magnetic properties and Mössbauer spectroscopy of Cu-Mn substituted BaFe12O19 hexaferrites
    (Elsevier Ltd, 2017) Baykal, Abdulhadi; Güngüneş, Hakan; Sözeri, Hüseyin; Amir, Md.; Auwal, İsmail A.; Asiri, Sarah Mousa; Shirsath, Sagar E.; Demir Korkmaz, Ayşe
    In this study, bimetallic (Cu-Mn) substituted M-type Ba 1-2x Mn x Cu x Fe 12 O 19 (0.0 ? x ? 0.1) hexaferrites were fabricated via sol-gel auto-combustion route. The effect of bimetallic substitution on structure, morphology and magnetism of BaFe 12 O 19 was studied. Scanning Electron Microscopy confirm images reveal the nanosize of the prepared products with flake morphology. X-ray powder diffraction analysis confirmed their complete conversion to BaFe 12 O 19 hexagonal crystal phase. The results from the magnetic investigations conducted by Vibrating Sample Magnetometer (VSM) and 57 Fe Mössbauer suggested that the saturation magnetization (M s ) and the coercive field of Ba 1-2x Mn x Cu x Fe 12 O 19 hexaferrites decrease as the concentration of Cu and Mn increases. The cation distribution calculation showed that the occupancy of Fe 3+ ions is increased at 12k and 2b sites with the increase in Cu and Mn substitution. © 2017 Elsevier Ltd and Techna Group S.r.l.
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    Magneto-optical properties of BaCryFe12?yO19 (0.0???y???1.0) hexaferrites
    (Elsevier B.V., 2018) Asiri, Sarah Mousa; Güner, Sadık; Demir Korkmaz, Ayşe; Amir, Md.; Mujasam Batoo, Khalid; Almessiere, Munirah Abdullah; Güngüneş, Hakan; Sözeri, Hüseyin; Baykal, Abdulhadi
    In this study, nanocrystalline BaCryFe12?yO19 (0.0???y???1.0) hexaferrite powders were prepared by sol–gel auto combustion method and the effect of Cr3+ ion substitution on morphology, structure, optic and magnetic properties of Barium hexaferrite were investigated. X-ray powder diffraction (XRD) analyses confirmed the purity of all samples. The XRD data shows that the average crystallite size lies between 60.95?nm and 50.10?nm and same was confirmed by Transmission electron microscopy. Transmission electron and scanning electron microscopy analyses presented the hexagonal morphology of all products. The characteristic hysteresis (?-H) curves proved the ferromagnetic feature of as grown nanoparticle samples. Specific saturation magnetization (?s) drops from 46.59 to 34.89?emu/g with increasing Cr content while the coercive field values lie between 770 and 1652?Oe. The large magnitude of the magnetocrystalline (intrinsic) anisotropy field, (Ha) between 11.0 and 12.6?kOe proves that all products are magnetically hard. The energy band gap values decrease from 2.0?eV to 1.84?eV with increasing Cr content. From 57Fe Mössbauer spectroscopy, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values were determined and discussed.
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    Mössbauer analysis and cation distribution of Zn substituted BaFe12O19 hexaferrites
    (Springer New York LLC, 2018) Auwal, İsmail A.; Demir Korkmaz, Ayşe; Amir, Md.; Asiri, Sarah Mousa; Baykal, Abdulhadi; Güngüneş, Hakan; Shirsath, Sagar E.
    Barium hexaferrite is a well-known hard magnetic material. Doping using nonmagnetic cation such as Zn2+ were found to enhance magnetization owing to preferential tetrahedral site (4 f 1) occupancy of the zinc. However, the distribution of cations in hexaferrites depends on many factors such as the method of preparation, nature of the cation, and chemical composition. Here, Zn-doped barium hexaferrites (Ba1?xZnxFe12O19) were synthesized by sol-gel method. In this study, we summarized the magnetic properties of Ba1?xZnxFe12O19 (x = 0, 0.1, 0.2, 0.3) BaM, investigated by Mössbauer spectroscopy. Moreover, cation distribution was also calculated for all the products. Mössbauer parameters were determined from 57Fe Mössbauer spectroscopy and according to it, the replacement of Ba-Zn affects all parameters such as isomer shift, the variation in line width, hyperfine magnetic field, and quadrupole splitting. Cation distribution revealed the relative area of undoped BaM, 12k, 2a, and 4 f 2 positions which are close to theoretical values.
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    Structural, optical and mössbauer study of Ba1???xCuxFe12O19 (0.5???x) nano hexaferrites
    (Springer New York LLC, 2018) Asiri, Sarah Mousa; Amir, Md.; Güner, Sadık; Güngüneş, Hakan; Mujasam Batoo, Khalid; Sertkol, Murat; Imran, Ahamad; Baykal, Abdulhadi
    In this study, a novel Ba1?xCuxFe12O19 (0.5???x) nano-hexaferrites were prepared by a simple and cost-effective sol–gel auto-combustion method using barium nitrates, iron nitrate, copper (II) acetate monohydrate and citric acid, and its structural, optical properties and hyperfine interactions were reported. Structural properties were analyzed through XRD (X-ray diffraction), Scanning electron microscopy (SEM), and TEM (Transmission electron microscopy), while percent diffuse reflectance spectroscopy (DRS) and Mössbauer spectrometer were used for analyzing the optical and magnetic properties of the resultant products. The observed Mössbauer studies proved the ferromagnetic nature of nanoparticles (NPs) samples. The crystallite size (XRD) varies in a range of (23.30–35.12) nm. The direct optical energy band gap (E g ) of all samples were calculated by Tauc plots where the E g values are found in a small range of 1.97–2.15 eV. The experimental evidences signify the promising use of newly prepared nano-hexaferrites in the development of materials in various industrial devices and far better than the conventional available hexaferrites materials.
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    Synthesis and characterization of Cu–Mn substituted SrFe12O19 hexaferrites
    (Springer New York LLC, 2018) Amir, Md.; Baykal, Abdulhadi; Güngüneş, Hakan; Asiri, Sarah Mousa; Ercan, İsmail; Shirsath, Sagar E.
    In this study, bimetallic (Cu–Mn) substituted SrFe12O19 hexaferrites [Sr1?2xMnxCuxFe12O19 (0.0???x???0.1)] were synthesized via sol–gel auto-combustion approach. The effect of bimetallic substitution on structure, morphology and magnetism of SrFe12O19 was investigated. SEM images divulge the nano-size of the prepared products with speck morphology. X-ray powder diffraction analysis affirmed their complete conversion to SrFe12O19 hexagonal crystal phase. The results from 57Fe Mössbauer suggested that all five important sextets of Sr1?2xMnxCuxFe12O19 hexaferrites effected due to the substitution of Cu and Mn ions. Cation distribution calculation showed that as the percentage of Mn and Cu increased in Sr1?2xMnxCuxFe12O19 (0.0???x???0.1), particularly for x?=?0.03 the relative area of 12k and 4f2 site increased. This indicates that Fe ions are migrated towards 12k and 4f2 octahedral site.