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| 1 | Morphology and magnetic traits of strontium nanohexaferrites:Effects of manganese/yttrium co-substitution显示文摘Doped strontium(Sr) hexaferrites appeared potential candidates for microwave absorber applications.Driven by this idea, we examined the influence of manganese(Mn) and yttrium(Y) co-substitution on the microstructures,morphology and magnetic properties of Sr nanohexaferrites(Sr1-xMnxFe12-yYyO19,where 0.0 ≤ x = y ≤ 0.5) synthesized via citrate sol-gel auto-combustion technique. As-prepared samples were thoroughly characterized using diverse analytical tools. X-ray diffraction pattern reveals a single Mhexagonal crystalline phase. FE-SEM, TEM, HR-TEM show a hexagonal platelet-like structure. The magnetic hysteresis loops(measured at room and low temperature) of the as-prepared nanohexaferrites exhibit ferromagnetic(FM) behavior. Magnetic parameters including the saturation magnetization,remanence, coercive and magneto-crystalline anisotropy field are found to decrease with the increase in Mn2+ and Y3+ contents. Zero-and normal-field cooled magnetization measurements in the range of 2-400 K display the complete absence of blocking temperature, confirming the characteristic ferromagnetic behavior of the proposed composition. | M.A.Almessiere Y.Slimani H.S.El Sayed A.Baykal | 2019 | Journal of Rare Earths2019，37，7： | 4 |
| 2 | Unique structural and magnetic traits of Nd3+-substituted Co-Zn nanoferrites显示文摘Because of the technological potential of magnetic spinel nanoferrites, we prepared neodymium ion(Nd3+)-substituted cobalt-zinc ferrites(CZFs) with the form Co0.5 Zn0.5 NdxFe2 exO4(0.03≤x≤0.05) via a hydrothermal method. The as-prepared samples were thoroughly characterized using various analytical techniques. XRD, FTIR and FESEM analyses confirm the formation of a cubic spinel phase of the CZFNPs(CZF nanoparticles). A decrease in the lattice parameter due to the substitution of Fe3+by Nd3+in the lattice structures is manifested in the XRD refinement data. The magnetic properties of the proposed CZFNPs were evaluated in terms of the saturation magnetization, remanence, coercivity, squareness ratio and magnetic moment. These CZFNPs exhibit superparamagnetic behaviors at room temperature.Moreover, the Nd3+inclusion does not significantly affect the measured magnetizations and coercivities of the CZFNPs. Samples containing 0.01 and 0.03 Nd3+exhibit lower saturation magnetizations than that of the pristine product. The squareness ratios much less than 0.53 are ascribed to surface spin disordering. The unique magnetic traits of the synthesized CZFNPs are primarily attributed to the substitution of Fe3+ions, with smaller ionic radii, by Nd3+ions, with larger ionic radii. The proposed CZFNPs may be useful for diverse magneto-optic applications. | M.A.Almessiere | 2019 | Journal of Rare Earths2019，37，10： | 1 |
| 3 | Electrical and dielectric properties of Ni_(0.5)Co_(0.5)Ga_(x)Fe_(1.8-x)O_(4)(x≤1.0)spinel ferrite microspheres显示文摘Microspheres of Ni_(0.5)Co_(0.5)Ga_(x)Fe_(2-x)O_(4)(x≤1.0)microsphere spinel ferrites(NiCoGaFe-MSFs)and carbon spheres were prepared via a hydrothermal technique.The micro structure of microspheres was investigated through scanning and transmission electron microscopy(SEM and TEM),respectively,and X-ray diffraction(XRD).The electrical and dielectric properties of NiCoGaFe-MSF at temperatures ranging from20 to 120℃(between 293,1×10^(3)and 393.1×10^(3))for f≤3.0 MHz were systematically studied as a result of 3D graphical drawing of the data obtained from an impedance analyzer.Relevant parameters such as ac/dc conductivity,dielectric loss,dielectric constant,activation energy,dissipation factor and Cole-Cole impedance spectra were extensively evaluated for various Ga ion mole ratios in the substitution where x≤1.0.We notice that the ac conductivity mostly obeys exponential power law rules,which vary significantly with the substitution ratios of Ga ions.Impedance analyses confirm that differences in conduction mechanisms in NiCoGaFe-MSFs are mainly due to grain-to-grain boundaries related to Ga ion substitution ratios.The change in dielectric constant of NiCoGaFe-MSFs is strongly dependent on the substitution rates and results in a normal dielectric distribution with frequency.The tangential loss for all micro spheres is observed to vary with measured temperatures and their frequency dependencies can be attributed to the conduction mechanism similar to Koop’s phenomenological model.It is clearly seen that the formation of semicircles is dominated by all the NiCoGaFe-MSFs and the diameter of the semicircles mostly decreases with increasing temperature,as evidence of a temperaturedependent relaxation mechanism. | S.Akhtar M.A.Almessiere B.Unal A.Demir Korkmaz Y.Slimani N.Tashkandi A.Baykal A.Ul-Hamid A.Manikandan | 2023 | Journal of Rare Earths2023，41，2： | 1 |
| 4 | AC susceptibility and FC-ZFC magnetic properties of SrTb_(x)Fe_(12-x)O_(19) and SrTm_(x)Fe_(12-x)O_(19) hexaferrites:a comparative study显示文摘In this comparative study,Tb and Tm substituted Sr-hexafe rrites(HFs) with the chemical compositions of SrTb_(x)Fe_(12-x)O_(19) and SrTm_(x)Fe_(12-x)O_(19)(x=0.00,0.02 and 0.04) were fabricated via citrate sol-gel approach.The AC susceptibility and FC-ZFC magnetization were investigated.The product structure and morphologies were also investigated via XRD,TEM and SEM along with EDX.Measurements of temperature dependence of magnetization M-T and AC magnetic susceptibility versus temperature were carried out.The various synthesized HFs displayed ferrimagnetic behavior within 10-325 K.At lower temperatures,super-spin glass-like behavior was noticed.Neel-Arrhenius and Vogel-Fulcher models were employed to explore the experimental data of AC susceptibility. | Y.Slimani M.A.Almessiere A.Demir Korkmaz A.Baykal I.Ercan | 2021 | Journal of Rare Earths2021，39，8： | 0 |
| 5 | Structural,morphological and magnetic properties of(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)nanoparticles prepared via sonochemical approach显示文摘The impact of Ga^(3+)and Gd^(3+)co-substitution on different types of behavior of Ni-Co nanospinel ferrites(NSFs),(Ni_(0.5)Co_(0.5))[Ga_(x)Gd_(x)Fe_(2-2x)]O_(4)(0.000≤x≤0.025),was investigated.NSFs were fabricated through ultrasound irradiation.The structure,composition,and spherical morphology of all products were verified by numerous characterization techniques such as X-ray diffraction(XRD),scanning and transmission electron microscopes(SEM and TEM),and selected area electron diffraction(SAED).Mossbauer spectra are composed of two ferromagnetic sextets and one paramagnetic doublet.These spectra were fitted to extract hyperfine parameters of the doped samples.Both sublattices'hyperfine magnetic field decreases with substitution.The isomer shift values show that the Mossbauer spectra are composed of magnetic Fe^(3+)sextets.The magnetization measurements at variable magnetic field(M-H)were investigated via a vibrating sample magnetometer(VSM)at temperatures(T)from 300 to 10 K.All NSFs disclose ferrimagnetic behavior at both 300 and 10 K at which they are soft and hard,respectively.We determined that the remanence magnetization(M_(r)),saturation magnetization(M_(s)),and magneton number(n_(B))decrease with increasing Ga^(3+)and Gd^(3+)ions contents.The reduction in these values is predominantly recognized to be the impact of cation redistribution and surface spins on tetrahedral(T_(d))and octahedral(O_(h))sites.As the Ga^(3+)and Gd^(3+)contents increase,the coercivity(H_(c))is also found to decrease. | Y.Slimani M.A.Almessiere A.Demir Korkmaz A.Baykal M.A.Gondal H.Güngünes Sagar E.Shirsath A.Manikandan | 2023 | Journal of Rare Earths2023，41，4： | 0 |
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