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Öğe Comparative study of nano-sized particles CoFe2O4 effects on superconducting properties of Y-123 and Y-358(Elsevier, 2014) Slimani, Yassine; Hannachi, Essia; Ben Salem, M. K.; Hamrita, A.; Varilci, AhmetThe effects of nano sized CoFe2O4 particles (10 nm) addition on the structural and the normal state resistivity of YBa2Cu3O7 (noted Y-123) and Y3Ba5Cu8O18 (noted Y-358) polycrystalline were systematically studied. Samples were synthesized in oxygen atmosphere using a standard solid state reaction technique by adding CoFe2O4 up to 2 wt%. Phases, microstructure and superconductivity have been systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical measurements rho(T). XRD results reveal that the lattice parameters change for both Y-123 and Y-358 phases. SEM observations reveal that the grain size is reduced with increasing the content of CoFe2O4. The measurements for the resistivity dependence of temperature show that the depression in superconducting temperature is more pronounced for CoFe2O4 addition in Y-358 compound than in Y-123 one. These results may be attributed to the existence of much more disorder due to a greater number of Cu sites to be substituted by Fe and Co in Y-358 compared to Y-123. Published by Elsevier B.V.Öğe Corrigendum to “The effect of Nb substitution on magnetic properties of BaFe12O19 nanohexaferrites” [Ceram. Int. 45 (2019) 1691–1697](S027288421832844X)(10.1016/j.ceramint.2018.10.048)(Elsevier Ltd, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Tashkandi ,Na Tashkandi; Baykal, Abdulhadi; Saraç, Mehmet Fahri; Belenli, İbrahimThe authors regret that in the published version of this article two additional affiliation addresses were missing for the author A.V. Trukhanov. The affiliation additional addresses are: National University of Science and Technology MISiS, 119049, Moscow, Leninsky Prospekt, 4, Russia South Ural State University, 454080, Chelyabinsk, Lenin Prospect, 76, Russia The authors would like to apologise for any inconvenience caused. © 2018 Elsevier Ltd and Techna Group S.r.l.Öğe Effect of bimetallic (Ca, Mg) substitution on magneto-optical properties of NiFe2O4 nanoparticles(Elsevier Sci Ltd, 2019) Slimani, Yassine; Almessiere, M. A.; Nawaz, M.; Baykal, A.; Akhtar, S.; Ercan, I; Belenli, İbrahimNanoparticles (NPs) of calcium and magnesium co-substituted nickel ferrite with the chemical composition CaxMgxNi1-2xFe2O4 (0.00 <= x <= 0.05) NPs were prepared hydrothermally. The (Ca, Mg) co-substitution effect on morphological, structural, optical and magnetic properties of NiFe2O4 NPs was analyzed via FT-IR, XRD, TEM, SEM, DRS and VSM techniques. The magnetization of CaxMgxNi1-2xFe2O4 (0.00 <= x <= 0.05) NPs were examined and analyzed at room temperature (300 K; RT) and low temperature (10 K). The specific magnetic parameters such as saturation magnetization M-s, remanence M-r, coercivity H-c, squareness ratio (SQR = M-r/M-s) and magnetic moment nB of Ni1-2xMgxCaxFe2O4 (0.00 <= x <= 0.05) NPs were determined and evaluated. The M (H) curves exhibit superparamagnetic behavior at RT and ferrimagnetic nature at 10 K. The substitution significantly changes the magnetizations and coercivity data. An increase in the M-s, M-r, H-c, and nB values was observed in substituted products compared to pristine one. The highest values were obtained for x = 0.05 product. The SQR values are found to be below than 0.5, which can be attributed to surface spin disorder effects. The obtained magnetic results are primarily derived from the substitution with Mg and Ca that will strengthen the super exchange interactions.Öğe The effect of Nb substitution on magnetic properties of BaFe12O19 nanohexaferrites(Elsevier Ltd, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Tashkandi ,Na Tashkandi; Baykal, Abdulhadi; Saraç, Mehmet Fahri; Belenli, İbrahimMicrostructural and magnetic properties of BaFe12-xNbxO19 (0.0 ? x ? 0.1) nanohexaferrites (NHFs) have been investigated intensively in this work. The Ba NHFs are synthesized through sol-gel auto-combustion route. The formation of single phase Ba NHFs, in different samples are confirmed by XRD powder patterns, scanning electron microscopy and Fourier Transform Infrared spectroscopy. The magnetic properties of BaFe12-xNbxO19 (0.0 ? x ? 0.1) NHFs were performed at room and low temperatures and discussed in detail. The analysis of hysteresis loops divulged that the different products display hard ferromagnetic behavior at different temperatures. The deduced values of saturation magnetization (Ms), remanence (Mr), magneton number (nB) and magneto crystalline anisotropy constant (Keff) are reduced for lower Nb content and then increased with further increasing the Nb content, reaching a maximum values for BaFe11.9Nb0.1O19 (x = 0.1) nanohexaferrite. The coercivity (Hc) and intrinsic coercivity (Hci) are diminished for lower x and are comparable to that of pristine one for higher x. The squareness ratio (Mr/Ms) are fluctuating between 0.50 and 0.55, implying the uniaxial anisotropy for different BaFe12-xNbxO19 nanohexaferrite. © 2018 Elsevier Ltd and Techna Group S.r.l.Öğe Magnetic and structural characterization of Nb 3+ -substituted CoFe 2 O 4 nanoparticles(Elsevier Ltd, 2019) Almessiere, Munirah Abdullah; Slimani, Yassine; Güner, Sait Barış; Nawaz, Muhammed; Belenli, İbrahimThis study investigated the effect of Nb 3+ substitution on the magnetic and structural properties of CoFe 2 O 4 nanoparticles (NPs) synthesized by hydrothermal approach. The formation of a single phase of spinel ferrite was confirmed through X-ray powder diffraction, and crystallite sizes in the range 18–30 nm were observed. Moreover, it found that the Fourier transform infrared (FT-IR) spectra of the NPs included the main vibration bands of the spinel structure. The partially cubic structure was confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The energy band gaps for CoNb x Fe 2-x O 4 were estimated to be in the range 0.48–0.53 eV for Nb 3+ content x = 0.0–0.10. Magnetization measurements at room temperature (RT; 300 K) and at 10 K were performed on spinel CoNb x Fe 2-x O 4 (0.00 ? x ? 0.10) NPs using a vibrating sample magnetometer (VSM). Nb 3+ doping significantly changed the magnetization and coercivity of the Co ferrite samples. RT hysteresis curves indicated well-defined ferrimagnetic behavior for all prepared NPs with saturation magnetization (M s ) in the range 44.45 – 49.40 emu/g and remanent magnetization (M r ) in the range 12.16 – 17.90 emu/g. The coercive field (H c ) is found to be equal 936 Oe and is decreased with Nb 3+ substitutions. However, hysteresis curves at 10 K showed finite remanent specific magnetization (1.90–6.70 emu/g) but significant asymmetric coercivity (715–2810 Oe), particularly for the Nb 3+ -doped samples. At 10 K, the magnetization values were 4–6 times smaller but symmetric coercivity field values were 2–3 times larger compared with the RT-VSM curves. The obtained magnetic parameters indicated the semi-hard magnetic character of the Co ferrite samples at low temperatures. © 2019 Elsevier Ltd and Techna Group S.r.l.
