Ba1−xZnxFe12O19 (0.0≤x≤0.3) hexaferrites were produced via sol-gel auto combustion technique. XRD patterns show that all the samples are single-phase M-type barium hexaferrite (BaM). Scanning ...electron microscopy (SEM) revealed that grains have a size range of 0.5–2µm. The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature of NPs. The average crystallite sizes were calculated by applying Scherrer equation on the base of XRD powder patterns of all samples and found to be in the range of 16.78–48.34nm. In particular, Ba1−xZnxFe12O19 (0.0≤x≤0.3) hexaferrites have suitable magnetic characteristics (saturation magnetization in a range of 63.00–67.70emu/g and coercive field in a range of 822–1275Oe) for magnetic recording and permanent magnets. Effective crystalline anisotropy constants (Keff) are between 4.20×105 and 4.84×105Erg/g. Magnetic moment increased by the substitution of non-magnetic Zn2+ ions. The anisotropy field (Ha) or intrinsic coercivity values above 13255Oe reveals that all samples are magnetically hard materials. Tauc plots were drawn to specify the direct optical energy band gap (Eg) of NPs. The Eg values are in a narrow range between 1.69eV and 1.76eV.
•Diamagnetic Zn2+ ionsubstitution on magnetic and optical properties of barium hexaferrite has been investigated.•All products are ferromagnetic.•The grain sizes are much larger than the critical dimension of 431nm to exhibit single-domain nature.
(BaTiO
3
–SrTiO
3
)/(WO
3
)
x
ceramics with
x
= 0 up to 5% were synthesized using solid-state reaction via high-energy ballf milling technique. Various characterization techniques were used ...including X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FT-IR), and UV–visible diffuse reflectance (DR) spectrophotometer. Structural analysis via XRD indicates the formation of two separate phases of SrTiO
3
(STO) and BaTiO
3
(BTO) having both cubic structures. The presence of BaWO
4
as impurity was detected for higher concentration. SEM observations show a reduction in the average grains size with increasing WO
3
addition. In comparison with free-added ceramic, the optical band gap energy (
E
g
) shows a slight increase with WO
3
addition. Contextual investigations on the electrical and dielectric properties of various WO
3
added to BTO–STO ceramics have been used to evaluate conductivity (
σ
), dielectric constant and loss (
ε
r
′
and
ε
r
″
), and dissipation factor (
t
a
n
δ
) against both frequency and dc bias voltages. Generally, both
σ
and
ε
r
″
correspond to the tendency of the power law to frequency. However, dc bias has been noticed to be lesser affecting the conduction mechanisms, which has a small variation for various WO
3
addition ratios. In addition, the dissipation factor was found to be highly dependent on both the addition ratio and the frequency as well as dc bias applied.
Nanospinel Li2xCu1-xAlyFe2-yO4 ferrites with composition x = y = 0.0, 0.2, 0.3 and 0.4, were successfully synthesized via hydrothermal method. The effect of co-substitution (Li and Al) on structural, ...morphological and magnetic properties of CuFe2O4 nanoparticles were investigated using Powder X-ray Diffraction (XRD), Fourier-Transform Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mossbauer spectroscopic techniques. The cation distribution of all composition was calculated. Both XRD and FT-IR analyses confirmed the synthesis of single-phase spinel cubic product for all the substitutions. Mossbauer investigation showed that the Li1+ and Al3+ ions occupied B-sites. Nonetheless, some amounts of Li1+ occupy A-site. The magnetization hysteresis loops M (H), revealed that the final products with x, y = 0.0, 0.3 and 0.4 exhibit superparamagnetic (SPM) behavior at room temperature, however the composition x, y = 0.2 displays a ferromagnetic-like (FM) behavior. The saturation magnetization (Ms) reduces with rising the Li and Al contents. Compared to pristine CuFe2O4 spinel, the remanent magnetization (Mr), coercive field (Hc) and the magneto-crystalline anisotropy fields (Ha) improved for products synthesized with x, y = 0.2 and then decrease for x, y = 0.3 and 0.4. The squareness ratio Mr/Ms are less than 0.500, which suggest the single domain nanoparticles with uniaxial anisotropy for Li2xCu1–xAlyFe2-yO4 (0.0 ≤ x, y ≤ 0.4) nanoparticles. The magneto-crystalline anisotropy constant (Keff) value is improved for Li0.8Cu0.6Al0.2Fe1.8O4 (i.e. x, y = 0.2) magnetic nanoparticles and then decreased for higher Li and Al contents, due to the replacement of Cu and Fe ions with respectively Li and Al ions.
Nanorod shaped cobalt molybdate (CoMoO4) electro-catalysts synthesized by microwave combustion route using urea as the fuel. The formation of monoclinic nanocrystalline structure, metal-oxygen (M–O) ...and chemical bonding was confirmed by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopy, respectively. Scanning electron microscope (SEM) associated with energy dispersive X-ray (EDX) and high-resolution transmission electron microscope (HR-TEM) were used to confirm the morphology, elemental composition and particle size of the samples, respectively. The optical and defects were confirmed by the UV–vis. absorption and photoluminescence (PL) spectroscopy at room temperature (RT). The room temperature magnetic behaviors of product were investigated by vibrating sample magnetometer (VSM). Surface binding energy and element confirmation were examined by X-ray Photoelectron spectroscopy (XPS). The electrochemical (EC) performance was studied by cyclic voltammetry (CV), galvanostatic charge-discharge analysis (GCD) and electrochemical impedance spectroscopy (EIS) analysis. The CV curve proved the existence of redox pairs and the supercapacitor nature exhibited by the EIS (Nyquist plots). The GCD studies provided the non-symmetrical discharge curves and the highest specific capacitance (Csp) of ~ 133 F/g were acquired at a constant discharge current density (1 mA/cm−2). The cyclic stability investigations revealed capacitance retention of about 100% after 1000 cycles, proposing the prospective usage of CoMoO4 in energy-storage devices.
•Rare earth element Ce3+ doped CuFe2O4 NPs prepared by simple sol-gel route.•Ce3+ ions were fruitfully substituted into CuFe2O4 matrix without any distortion.•XRD and SEM along with EDX studies ...confirmed the spinel phase formation.•Magnetic properties altered by the substitution of Ce3+ into CoFe2O4 matrix.
In the present study, spinel copper ferrite (CuFe2O4) nanoparticles (NPs) doped with different concentrations of rare earth element (REE) Cerium (Ce3+) ions were synthesized by the simple sol-gel combustion technique. REE Ce3+ ions were successfully doped into the spinel lattice of CuFe2O4 NPs without any distortion. It was analyzed that the influence of Ce3+ ions on structure, surface morphology, magnetic behavior and antibacterial activities using different instrumental techniques such as powder XRD, SEM, EDX, TEM, SAED and VSM, etc. Powder XRD results and SEM images along with EDX techniques confirmed the spinel phase formation of pure and Ce3+ doped CuFe2O4 NPs with spherical shaped morphology without any other secondary phase impurity. It also was further confirmed by TEM and SAED analysis. The magnetic behavior of the Ce3+ doped CuFe2O4 NPs was recorded using the VSM technique at room temperature (RT). The magnetic characterizations have been altered by the addition of Ce3+ ions in the CoFe2O4 lattice. The antibacterial properties of Ce3+ doped CuFe2O4 NPs was found to be enhanced with increase in Ce3+ concentrations as it cause a reduction in the grain size.
Yttrium doped barium hexaferrites with chemical composition BaYxFe12−xO19 (0.0≤x≤1.0) were synthesized by facile ceramic route. The effect of the yttrium ion concentration on the ...temperature-dependent magnetic properties of the BaYxFe12−xO19 hexaferrites (0.0≤x≤1.0) has been investigated in the temperature range of 10–300K and magnetic field of 50kOe. The structural, morphological, compositional and magnetic properties of the products were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM) techniques, respectively. XRD patterns demonstrated pure, single phase hexagonal crystal. The average crystallite size of the samples varies in the range of 47–63nm. SEM images indicated hexagonal platelet-like particles. EDX measurements confirmed the expected formula of BaYFe11O19 hexaferrite. It has been observed that the preferential site occupancy of the nonmagnetic yttrium ions strongly changes the magnetic properties. The saturation magnetization value close to the bulk one was measured as 62.62 and 88.21emu/g for 300 and 10K, respectively. It has been found from the magnetization measurements that the saturation magnetization reaches its maximum value at x=0.4 and then decreases with further increasing of the concentration (x). As the temperature goes up, the saturation magnetization decreases due to the weakening of superexchange interaction. The coercive field increases by about three times with increasing of the concentration from x=0.0 to 1.0 due to an increasing of anisotropy field and reaches the maximum value of 3556Oe at x=1.0.
Abstract
Kundt’s class of gravitational wave metrics belonging to Petrov type-N are constructed for generic f(R) model with minimally coupled electromagnetic feld, a Gauss-Bonnet extended ...gravitational model for vacuum in four spacetime dimensions, and RF
2
-type nonminimally coupled Einstein-Maxwell models including a cosmological constant.
In this study, we reported the degradation of organic dyes (methyl orange, MO and methylene blue, MB) by Fe3O4@His@Ag MRC in which histidine was used as linker. The size of crystallite of MRC was ...calculated as 19nm. The M–H hysteresis loop of the product indicates that it exhibits superparamagnetic property at room temperature. Catalytic studies showed that this product could catalyze the degradation of MO and MB in a reasonable time. Moreover, the product can be recycled five times by magnetic separation without major loss of its activity. Thus, Fe3O4@His@Ag MRC can be served as an effective and convenient recyclable nanocatalyst for azo dye degradation and hence as an environmental protection application too.
Spinel Mg1-xNixFe2O4 (x = 0.0, 0.6, 1.0) nanoparticles were synthesized via chemical co-precipitation method and were studied their structural, magnetic, optical and photocatalytic properties. XRD ...and TEM analysis was confirmed the cubic spinel phase belonging to the space group Fd3m and the average crystallite size (D) is around 20–30 nm. The magnetic studies at room temperature were recorded using VSM and the loops obtained results indicated ferrimagnetism. The optical studies showed absorption activity in the visible region, thus making the synthesized materials suitable for photocatalytic applications and was tested by applying it for the degradation of methylene blue. Increased the amount nickel substitution, photocatalytic activity is enhanced due to their narrow band gap energy making it suitable for waste water treatment.
•Mg1-xNixFe2O4 NPs was synthesized by chemical co-precipitation method.•XRD analysis confirmed the cubic spinel phase belonging to space group Fd3m.•Pore size distribution calculated from Barrett-Joyner- Halenda (BJH) method.•Magnetic studies of the samples indicated ferrimagnetism behavior.•Spinel Mg0.4Ni0.6Fe2O4 showed higher photocatalytic activity.
BaTiO
3
/(WO
3
)
x
ceramics (where x = 0, 0.5, 1, 2 and 5 wt%) were prepared by solid state reaction. X-ray powder diffraction, scanning electron microscope, Fourier transform-infrared spectroscopy ...and ultraviolet–visible diffuse reflectance spectrophotometry were used to investigate the structure, morphology and optical properties, respectively. The electrical and dielectric properties were also performed for different synthesized ceramics. A pure phase was obtained for x = 0.5 wt% ceramic, nevertheless a secondary phase was detected for x ≥ 1 wt% ceramics. The grains size increases for x = 0.5 wt% ceramic and then reduces abruptly with further increasing WO
3
content. The increase of grains size and the absence of impurities were all efficient to enhance the dielectric properties. A suitable WO
3
content leads to obtain ceramics having high dielectric constant and low tangent loss, which is encouraging for radio frequencies and microwaves applications.
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