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Öğe 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.Öğe Electrical properties and hyperfine interactions of boron doped Fe3O4 nanoparticles(Academic Press, 2015) Amir, Md.; Ünal, Bayram; Geleri, M.; Güngüneş, Hakan; Shirsath, Sagar E.; Baykal, AbdulhadiThe single spinel phase nano-structured particles of FeBxFe2-xO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized by the glycothermal method and the effect of B3+ substitution on structural and dielectric properties of Fe3O4 were studied. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on B3+ substitution have been determined. The hyperfine field values at B- and A-sites gradually decrease with increasing B3+ ion concentration (x). The cation distributions obtained from Bertaut method are in line with Mössbauer results. Complex impedance analysis of boron-substituted spinel ferrites have been made extensively in order to investigate the significant changes in ac and dc conductivity as well as complex permittivity when the boron composition ratio varies from 0.1 to 0.5. It is found that both ac and dc conductivity are also dependent on the boron content in addition to both temperature and applied frequency. The dc conductivity tendency does not purely obey the Arrhenius plots. The dielectric constant and loss of complex permittivity, in general, show similar attitudes as seen in some nanocomposites containing spinel ferrites except for some fluctuations and shifts along the characteristics of the curves. Furthermore, their imaginary components of both permittivity and modulus are almost found to obey the power law with any exponent values varying between 0.5 and 2 in accordance with the level of boron concentrations. © 2015 Elsevier Ltd. All rights reserved.Öğe 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 MousaNickel 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.Öğe Magnetic properties and hyperfine interactions of Co1-2xNixMnxFe2O4 nanoparticles(Elsevier Ltd, 2017) Baykal, Abdulhadi; Eryiğit, Ş. Ş.; Topkaya, Ramazan; Güngüneş, Hakan; Amir, Md.; Yıldız, Aylin; Kurtan, Ümran; Shirsath, Sagar E.Co1-2xNixMnxFe2O4 (0.0?x?0.5) nanoparticles (NPs) were prepared via citrate assisted microwave combus-tion route. XRD analysis confirmed the cubic structure (spinel) of all samples. Average crystallite size ofproducts (obtained from (311) diffraction line) was in the range of 32.9–43.4 nm. The intense peak appearing ataround 531 cm?1in FT-IR was attributed to the formation of a spinel ferrite. Magnetic properties of theproducts were investigated by room temperature vibrating sample magnetometer and Mössbauer spectroscopy.The magnetic parameters have been found to strongly depend on the Ni and Mn concentrations. The saturationmagnetization continuously decreases with the increasing of the concentration (x). We found thatNi0.5Mn0.5Fe2O4NP has superparamagnetic character at room temperature. This result was also verified byMössbauer analysis. Scanning electron microscopic analysis revealed the cubic morphology of all products, EDXand elemental mapping analyses confirmed the expected composition of each product.Öğe 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, AyşeIn 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.Öğe Magnetic properties of FeMnyCoyFe2?2yO4@Oleylamine nanocomposite with cation distribution(Springer New York LLC, 2017) Amir, Md.; Demir Korkmaz, Ayşe; Baykal, Abdulhadi; Geleri, M.; Sözeri, Hüseyin; Güngüneş, Hakan; Sertkol, Murat; Shirsath, Sagar E.In this study, oleylamine (OAm) capped FeMnyCoyFe2?2yO4 (0.0???y???0.4) nanocomposites (NCs) were prepared via the polyol route and the impact of bimetallic Co3+ and Mn3+ ions on the structural and magnetic properties of Fe3O4 was investigated. The complete characterization of FeMnyCoyFe2?2yO4@OAm NCs were done by different techniques such as XRD, SEM, TGA, FT-IR, TEM, and VSM. XRD analyses proved the successful formation of mono-phase MnFe2O4 spinel cubic products free from any impurity. The average crystallite sizes were calculated in the range of 9.4–26.4 nm using Sherrer’s formula. Both SEM and TEM results confirmed that products are nanoparticles like structures having spherical morphology with small agglomeration. Ms continued to decrease up to Co3+ and Mn3+ content of y?=?0.4. Although Mössbauer analysis reveals that the nanocomposites consist three magnetic sextets and superparamagnetic particles are also formed for Fe3O4, Co0.2Mn0.2Fe2.6O4 and Co0.4Mn0.4Fe2.2O4. Cation distributions calculation was reported that Co3+ ions prefer to replace Fe2+ ions on tetrahedral side up to all the concentration while Mn3+ ions prefer to replace Fe3+ ions on the octahedral.Öğe Magneto optical properties and hperfine interactions of Cr3+ Ion substituted copper ferrite nanoparticles(Springer New York LLC, 2018) Baykal, Abdulhadi; Güner, Sadık; Güngüneş, Hakan; Mujasam Batoo, Khalid; Amir, Md.; Manikandan, A.Spinel CuCrxFe2?xO4 (0.0???y???1.0) nanoparticles were fabricated by co-precipitation. X-ray diffraction proved the pureness and cubic crystal assembly of products which have the crystallite sizes varying between 16 and 33 nm. The cubic morphology and expected chemical composition, spectral analyses of all sample were accomplished via Scanning electron microscopy along with Energy Dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy respectively. Magnetic and optical characterization of samples were done via Vibrating sample magnetometer, Mössbauer spectroscopy and Diffuse reflectance spectroscopy. Kubelka–Munk model was applied to UV–Vis data for calculating the optical Eg (band gap) values between minimum 1.20 and maximum 1.80 eV. Mössbauer analysis determined the consequence of Cr3+ substitution on isomer shift and quadrupole splitting of all products etc. The specific magnetization (?-H) hysteresis curves have finite coercivity (in a range of 35–410 Oe) and retentivity (in a range of 0.33–3.84 emu/g) values and reveal the soft ferrimagnetic nature of spinel CuCryFe2?yO4 nanoparticles (NPs). The estimated saturation magnetization Ms value of 35.17 emu/g is maximum for pristine CuFe2O4 NPs and decreases to minimum value of 1.57 emu/g for CuCr0.4Fe1.6O4 NPs due to Cr3+ ion substitution. The calculated squareness ratios less than 0.5 assign the uniaxial anisotropy for all CuCryFe2?yO4 NPs. The magneto-crystalline anisotropy field (Ha) values less than 10.0 kOe except for the composition of CuCr0.2Fe1.8O4 NPs are other magnetic data to reveal the soft magnetic character of samples.Öğe Magneto-optical investigation and hyperfine interactions of copper substituted Fe3O4 nanoparticles(Elsevier Ltd, 2016) Amir, Md.; Baykal, Abdulhadi; Güner, Sadık; Güngüneş, Hakan; Sözeri, HüseyinCCopper substituted Fe3O4 nanoparticles (NPs) (CuxFe1?xFe2O4 (0.0?x?1.0)) were synthesized by polyol method and the effect of Cu2+ substitution on structural, magnetic and optical properties of Fe3O4 was investigated. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), UV–Visible spectroscopy and Vibrating sample magnetometer (VSM) were used to study the physical properties of the products. The room temperature (RT) magnetization (?–H) curves revealed the superparamagnetic nature of the products. The extrapolated specific saturation magnetization (?s) decreases from 42.69 emu/g to 14.14 emu/g with increasing Cu content (x). The particle size dependent Langevin fit studies were applied to determine the magnetic particle dimensions (Dmag). The average magnetic particle diameter is about 9.89 nm. The observed magnetic moments of NPs are in range of (0.61–1.77) µB and rather less than 4 µB of bulk Fe3O4 and 1 µB of bulk CuFe2O4. Magnetic anisotropy was assigned as uniaxial and calculated effective anisotropy constants (Keff) are between 10.89×104 Erg/g and 26.95×104 Erg/g. The average value of magnetically inactive layer for CuxFe1?xFe2O4 NPs was calculated as 1.23 nm. The percent diffuse reflectance spectroscopy (DR%) and Kubelka–Munk theory were applied to determine the energy band gap (Eg) of NPs. The extrapolated optical Eg values from Tauc plots are between minimum 1.98 eV to 2.31 eV. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer splitting, quadrupole splitting and hyperfine magnetic field values on Cu+2 ion substitution have been determined. Although, the Mössbauer spectra for the sample x=0.2 and 0.8 are composed of paramagnetic doublets, ferromagnetic sextets were also formed for other products.Öğe Magneto-optical properties and Mössbauer Investigation of BaxSryPbzFe12O19 Hexaferrites(Elsevier Ltd, 2017) Baykal, Abdulhadi; Yokuş, S.; Güner, Sadık; Güngüneş, Hakan; Sözeri, Hüseyin; Amir, Md.Ba0.3Sr0.4Pb0.3Fe12O19, Ba0.4Sr0.3Pb0.3Fe12O19 and Ba0.3Sr0.3Pb0.4Fe12O19 hexaferrites were synthesized via sol-gel auto combustion. XRD (X-ray powder diffraction) powder patterns of the products confirmed the formation of M-type hexaferrites without any secındary phase. The crystallite sizes of the products were calculated as 37–41 nm by Scherrer equation. SEM (Scanning electron microscopy) analyses revelaed the hexagonal morphology and 200–400 nm grain size of the prodcuts. The magnetic hysteresis (?-H) curves exhibit the ferromagnetic features for all hexaferrites. Especially, Ba0.3Sr0.4Pb0.3Fe12O19 and Ba0.4Sr0.3Pb0.3Fe12O19 samples have suitable magnetic characteristics (saturation magnetizations as 42.58 and 38.55 emu/g, coercive fields as 1950 and 2978 Oe, larger squareness ratios (SQR) as 0.447 and 0.454, respectively) for high density magnetic recording applications and permanent magnet fabrication. Effective crystalline anisotropy constants (Keff) are between 3.18×105–3.54×105 Erg/g. The observed 17000 Oe Ha (anisotropy field) reveal that products are hard magnet. Tauc plots were plotted to determine the Eg (direct optical energy band gap) of the samples. The Eg values are 1.46, 1.51, 1.69 eV belonging to Ba0.3Sr0.4Pb0.3Fe12O19, Ba0.4Sr0.3Pb0.3Fe12O19, and Ba0.3Sr0.3Pb0.4Fe12O19 hexaferrites respectively.Öğe 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, AbdulhadiIn 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.Öğe Microstructural, optical, and magnetic properties of vanadium-substituted nickel spinel nanoferrites(Springer New York LLC, 2019) Demir Korkmaz, Ayşe; Güner, Sadık; Slimani, Yassine; Güngüneş, Hakan; Amir, Md.; Manikandan, Ayyar; Baykal, AbdulhadiThe current study investigates the impact of vanadium substitution on the structural, magnetic, and optical properties of NiFe2?xVxO4 (x ? 0.3) nanoparticles (NPs) produced by the cost-effective sol-gel route. The as-prepared spinel ceramic powders were examined by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The functional groups, spinel phase, and crystal structure were confirmed by XRD and FT-IR, respectively. The crystallites size decreased from 45.24 to 36.56 nm as the doping process increases. The plots of Tauc were drawn to determine optical band gap magnitudes of 1.291, 1.302, and 1.312 eV for x = 0.0, 0.2, and 0.3, respectively. The estimated saturation magnetization is maximum for pristine NiFe2O4 NPs and decreases to minimum for NiFe1.7V0.3O4 NPs. The ?-H hysteresis loops have finite coercivity (between 125 and 169 Oe) and retentivity (between 9.36 and 14.04 emu/g) values. The calculated ?r/?s ratios are lower than 0.500, assigning the uniaxial anisotropy for NiFe2?xVxO4. The effective anisotropy constants (Keff) are in the range of 0.824 × 105 and 1.303 × 105 Erg/g. The magnetocrystalline anisotropy field (Ha) values are around 5.0 kOe. The characteristics of hysteresis (?-H) curves and the order of magnetic data reveal the soft ferrimagnetic feature of as-prepared nanoparticle samples. From Mossbauer analysis, the variations in hyperfine magnetic field, quadrupole splitting, line width, and isomer shift have been evaluated. The distribution of cations showed that the octahedral B sites are occupied by all the ions of V3+. Mossbauer spectra are composed of four Zeeman sextets and one doublet.Öğe 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.Öğe Mössbauer studies and magnetic properties of cubic CuFe2O4 nanoparticles(Springer New York LLC, 2019) Amir, Md.; Güngüneş, Hakan; Slimani, Yassine; Tashkandi, N. A.; El Sayed, H. S.; Aldakheel, F.; Sertkol, Murat; Sözeri, Hüseyin; Manikandan, A.; Ercan, İsmail; Baykal, AbdulhadiThis study reports the preparation and characterization of nanocrystalline spinel powder of cubic copper ferrite nanoparticles (NPs) which have been fabricated via a cost-effective citrate sol–gel approach. The structural and morphological properties of the nanoparticles are analyzed by X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), and scanning electron microscopy (SEM) whereas magnetic properties and Mössbauer analysis were performed using vibrating sample magnetometer (VSM) and Mössbauer spectra, respectively, and were characterized in detail. The empirical aim of this study is to perceive the transition phase of CuFe 2 O 4 as cubic symmetry which was confirmed by SEM images, and a couple of studies reported on the cubic structure of copper ferrite and discussed the magnetic properties. However, the present study gives the detailed information of the formation of cubic structure and magnetic behavior of the CuFe 2 O 4 cubic structure. X-ray diffraction measurements of resulting NPs show that the grain size of the particles is about 42.08 nm while SEM analysis showed that the particles have cubic nanostructured shapes with non-homogeneous sizes in around 80–100 nm. From 57 Fe, Mössbauer parameters consist of one superparamagnetic doublet and superposition of four sextets. VSM result shows the enhanced superparamagnetic nature of the CuFe 2 O 4 NPs. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Öğe 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, AbdulhadiIn 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.Öğe Substitution effect of Cr 3+ on hyperfine interactions, magnetic and optical properties of Sr-hexaferrites(Elsevier Ltd, 2018) Slimani, Yassine; Baykal, Abdulhadi; Amir, Md.; Tashkandi, N. A.; Güngüneş, Hakan; Güner, Sadık; El Sayed, H. S.; Aldakheel, F.; Saleh, Tawfik A.; Manikandan, A.Chromium-substituted strontium nano-hexaferrites, SrCrxFe12-xO19 (0.0?? x???1.0), were produced by the hydrothermal route. The structure, morphology, optical and magnetic properties were studied. Crystal structure, spinel phase and functional groups were verified using X-ray diffraction and Fourier Transform Infrared spectroscopy. The average crystallites size is ranging between 50 and 67?nm. Scanning electron microscopy observations indicated that the multi-grains of the particles are aggleromated and are hexagonal in shape. The isotherm plots obtained from the nitrogen physisorption experiments showed that the mesopore area and the total pore volume decreased progressively with increasing the Cr3+ content. Besides, the band gap energy (Eg) decreases from 1.75 to 1.43?eV. The magnetic hysteresis loops showed that the produced nano-hexaferrites exhibit hard ferromagnetic-like (FM) behavior. Compared to the pristine SrFe12O19 product, the deduced saturation (Ms) and remanent (Mr) magnetizations, the coercivity (Hc) and the magnetocrystalline anisotropy field (Ha) increase for lower Cr3+ content (x???0.4) and then decrease as the Cr3+ content further increases. The squareness ratio Mr/Ms are ranging between 0.5 and 0.6, suggesting the single domain nano-sized particles with uniaxial anisotropy for various synthesized products. Mossbauer analysis was done to determine the quadrupole splitting, the isomer shift, and the hyperfine magnetic field values of all products.Öğe 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.Öğe Synthesis and characterization of oleylamine capped MnxFe1-xFe2O4nanocomposite: Magneto-optical properties, cation distribution and hyperfine interactions(Elsevier Ltd, 2016) Güner, Sadık; Baykal, Abdulhadi; Amir, Md.; Güngüneş, Hakan; Geleri, M.; Sözeri, Hüseyin; Shirsath, Sagar E.; Sertkol, MuratPure Fe3O4 NPs and Oleylamin (OAm) capped MnxFe1-xFe2O4 (MnxFe1-xFe2O4@OAm) (0.2 ? x ? 1.0) nanocomposites (NCs) were synthesized by the polyol route. Lattice parameter increases with increasing Mn2+ concentration, due to the respective larger ionic radius of Mn2+ ion compared with the Fe2+ ion. The VSM analyses revealed superparamagnetic characteristics of all samples. The extrapolated specific saturation magnetization (?s) values decreased from maximum 50.74 emu/g to minimum 15.34 emu/g by increasing Mn content. The particle size dependent Langevin function was applied to determine the magnetic particle dimensions (Dmag) between 9.10 nm and 21.50 nm. The observed magnetic moments of NPs and NCs are in range of (0.64–2.10) ?B and significantly less than 4 ?B of bulk Fe3O4. Magnetic anisotropy was determined as uniaxial and calculated effective anisotropy constants (Keff) are between 32.14 × 104 Erg/g and 8.71 × 104 Erg/g. The size dependent saturation magnetization suggests the existence of a magnetically dead layers around the magnetic cores for NCs between 0.72 nm and 1.29 nm. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on Mn2+ substitution have been determined. Although, the Mössbauer spectra for the sample x = 0.2 is composed of ferromagnetic sextets, paramagnetic doublet is also formed for other samples. The percent diffuse reflectance spectroscopy (DR %) and Kubelka-Munk theory were used to specify the optical properties. The estimated optical band gap (Eg) values from Tauc plots are between 1.50 eV and 2.05 eV. Increasing Mn content in NCs increased the band gap at different magnitudes.Öğe Synthesis and structural and magnetic characterization of BaZn x Fe12?x O19 hexaferrite: hyperfine interactions(Springer New York LLC, 2017) Baykal, Abdulhadi; Sözeri, Hüseyin; Güngüneş, Hakan; Auwal, İsmail A.; Shirsath, Sagar E.; Sertkol, Murat; Amir, Md.To study the effect of Zn substitution on structural magnetic properties and hyperfine interactions of barium hexaferrite, BaFe12?x Zn x O19 (0.0?x?0.3) hexaferrites were synthesized via sol-gel auto-combustion technique. Rietveld analysis of XRD powder patterns confirmed the formation of single-phase hexaferrites for all products. Due to the larger ionic size of Zn2+ as compared with Fe3+, while x increases, the lattice constant parameters increase to a small degree. Nanoplate morphology of the products is presented by SEM analyses. It was observed that both saturation magnetization and coercivity decrease in almost the same manner with zinc concentration for all substitutions. Cation distribution calculations showed that Zn2+ occupies 12k, 4 f 2, 4 f 1, and 2b sites and at the same time pushes Fe3+ ions towards 2a and 12 k 1 sites. From57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, and hyperfine magnetic field values on Zn2+ substitution have been determined.
