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.
MnxFe3−xO4 (0.0≤x≤1.0) nanoparticles were synthesized by the polyol synthesis method and the effect of Mn3+ substitution on structural, magnetic and optical properties of Fe3O4 was studied. 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. The crystallite (from XRD) and particle sizes (from TEM and SEM) are in close agreement with each other. Lattice parameter increases with increasing Mn3+ concentration, due to the respective larger ionic radius of Mn3+ ion compared with the Fe3+ ion. The magnetic hysteresis (M–H) curves revealed superparamagnetic characteristics of the products. The extrapolated specific saturation magnetization (σs) values decreased from maximum value of 47.3emu/g to the minimum value of 25.6emu/g by increasing Mn composition. The particle size dependent Langevin function was applied to determine the magnetic particle dimensions (Dmag) around 15nm. The observed magnetic moments of NPs are in range of (1.06–1.96)µB and significantly less than 4µB of bulk Fe3O4. Magnetic anisotropy was offered as uniaxial and calculated effective anisotropy constants (Keff) are between 34.47×104Erg/g and 21.83×104Erg/g. The size-dependent saturation magnetization suggests the existence of a magnetically inactive layer as 1.638nm on FeMnxFe2−xO4 NPs. The UV–vis diffuse reflectance spectroscopy (DRS) and Kubelka−Munk theory were applied to determine the optical properties. The estimated optical band gap (Eg) values dropped almost linearly from 2.05eV to 1.17eV with increasing Mn composition.
Fe3O4@HA@Ag magnetic nanocomposites (MNCs) were successfully synthesized by the simple reflux method for the removal of azo dyes from the industrial aqueous media. Fe3O4@HA@AgMNCs exhibited high ...catalytic activity to reduce MB within 20min from the waste water. The obtained materials were characterized by the means of different techniques. Powder X-ray diffraction (XRD) analysis confirmed the single-phase of Fe3O4 spinel structure. SEM and TEM analysis indicated that Fe3O4@HA@AgMNCs were nanoparticles like structure with small agglomeration. TG result showed that the products contained 9% of HA. The characteristic peaks of HA at 1601cm−1 and 1703cm−1 was observed by the means of FT-IR spectra of Fe3O4@HA@AgMNCs. The hysteresis (σ–H) curves revealed Fe3O4@HA@Ag MNCs exhibit a typical superparamagnetic characteristic with a saturation magnetization of 59.11emu/g and measured magnetic moment is 2.45µB. The average magnetic particle dimension (Dmag) is 13.25nm. In accordance, the average crystallite and particle dimensions were obtained as 11.50nm and 13.10nm from XRD and TEM measurements, respectively. Magnetocrystalline anisotropy was offered as uniaxial and calculated effective anisotropy constant (Keff) is 2.96×105Erg/g. The blocking temperature was estimated as 522K. The size-dependent saturation magnetization suggests the existence of a magnetically dead layer as 0.793nm for Fe3O4@HA@Ag MNCs. The UV–vis diffuse reflectance spectroscopy (DRS) and Kubelka–Munk theory were applied to determine the optical properties of powder samples. The direct optical energy band gap (Eg) values were estimated from Tauc plots between 1.62eV and 2.12eV.
An illustration for the fabrication of Fe3O4@HA@Ag MNCs.
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•The reduction of azo dye such Methylene Blue was instantly completed with Fe3O4@HA@Ag MRCs.•Fe3O4@HA@Ag MRCs was used as heterogeneous catalyst.•Fe3O4@HA@Ag MRCs with the room-temperature magnetism showed that it could be used as a recyclable catalyst.•The direct Eg value of Fe3O4 NPs exhibits a remarkable increase from 1.62eV to 2.12eV after the HA coating.
Vanadium substituted nickel ferrite nanoparticles (NPs), NiFe
2−x
V
x
O
4
(0.0 ≤ x ≤ 0.3) were prepared by sol–gel approach. The influence of calcination on the magnetic and optical properties of ...NiFe
2−x
V
x
O
4
(0.0 ≤ x ≤ 0.3) NPs were investigated deeply. The lattice parameters ‘a’ are almost constant with V-substitution for as-prepared and calcined samples. It was found that the calcination process both increased the crystallites size and removed the impurity phases in all products. The values of optical energy band gap, E
g
, are in range of 1.38–1.69 eV and 1.39–1.56 eV for as-prepared and calcined samples, respectively. The specific magnetic parameters such as saturation magnetization M
s
, remanence M
r
, coercivity H
c
, squareness ratio (SQR) and magnetic moment
n
B
were determined from magnetization versus applied field measurements. The various M(H) curves exhibit ferromagnetic behavior at room temperature and 10 K. A decrease in M
s
, M
r
and
n
B
values was observed with Vanadium substitution. However, an increase in H
c
value was observed. The obtained magnetic results are primarily resulted from the substitution of Fe ions with V ions that will weaken the A–B super-exchange interactions. Besides, the calcination step leads to an improvement in the various M
s
, M
r
and
n
B
parameters. This enhancement is due to the enlargement of crystallites size (or grains size) and the strengthening of the A–B exchange interactions caused by the calcination effect. Nevertheless, the enlargement in the crystallites size is followed by a reduction in H
c
values.
Null mutations in genes involved in V(D)J recombination cause a block in B- and T-cell development, clinically presenting as severe combined immunodeficiency (SCID). Hypomorphic mutations in the ...non-homologous end-joining gene DCLRE1C (encoding ARTEMIS) have been described to cause atypical SCID, Omenn syndrome, Hyper IgM syndrome and inflammatory bowel disease-all with severely impaired T-cell immunity. By whole-exome sequencing, we investigated the molecular defect in a consanguineous family with three children clinically diagnosed with antibody deficiency. We identified perfectly segregating homozygous variants in DCLRE1C in three index patients with recurrent respiratory tract infections, very low B-cell numbers and serum IgA levels. In patients, decreased colony survival after irradiation, impaired proliferative response and reduced counts of naïve T cells were observed in addition to a restricted T-cell receptor repertoire, increased palindromic nucleotides in the complementarity determining regions 3 and long stretches of microhomology at switch junctions. Defective V(D)J recombination was complemented by wild-type ARTEMIS protein in vitro. Subsequently, homozygous or compound heterozygous DCLRE1C mutations were identified in nine patients from the same geographic region. We demonstrate that DCLRE1C mutations can cause a phenotype presenting as only antibody deficiency. This novel association broadens the clinical spectrum associated with ARTEMIS mutations. Clinicians should consider the possibility that an immunodeficiency with a clinically mild initial presentation could be a combined immunodeficiency, so as to provide appropriate care for affected patients.
•Tm substituted Co ferrite were fabricated by sonochemical method.•IT exhibited a superparamagnetic nature at RT for × = 0.00 and 0.02 samples and ferromagnetic nature in the other products.•Tm ...substitution affects considerably the magnetizations data.
Co-Tm nano-spinel ferrite with chemical formula CoTmxFe2−xO4 (0.0 ≤ x ≤ 0.08) NPs were prepared via sonochemical approach. X-ray powder diffraction patterns, microscopic images (SEM and TEM) and infrared spectra proved the formation of Co spinel ferrite. The effect of Tm3+ substituted on spinal structure was evaluated by lattice parameters, tetrahedral and octahedral bond length and cationic distribution. The band gap energy (Eg) of samples were estimated by performing UV–Vis percent diffuse reflectance (% DR) and applying the Kubelka-Munk theory. Eg values are in an interval between 1.33 eV and 1.64 eV. The analyses of magnetization were performed at room (300 K; RT) and low (10 K) temperatures. Different magnetic parameters including coercivity Hc, saturation magnetization Ms, remanence Mr, squareness ratio (SQR = Mr/Ms) and magnetic moment nB were deduced and discussed. The results showed superparamagnetic (SPM) nature at RT for x = 0.00 and 0.02 samples. However, the other products exhibit ferromagnetic (FM) nature. At 10 K, all synthesized NPs display FM behavior. An amazing increase in the magnitudes of Ms, Mr and Hc was observed at 10 K in comparison to RT, which is principally due to the reduced thermal fluctuations of magnetic moments at lower temperatures. The Tm3+ substitution affects considerably the magnetizations data. An enhancement in the Ms, Mr, and nB was detected on increasing the Tm3+ concentration. The SQR values at RT are found to be smaller than 0.5 postulating a single domain nature with uniaxial anisotropy for all produced ferrites. However, SQRs are in the range 0.66–0.76 at 10 K, suggesting the multi magnetic domain at low temperature, except the x = 0.02 product where the SQR = 0.47 indicating the single magnetic domain. The obtained magnetic results were investigated deeply with relation to structural and microstructural properties.
BaBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites were synthesized by sol–gel autocombustion method and the effects of Bi, La, Y substitutions on structural, magneto-optical properties of barium ...hexaferrite were investigated. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Vibrating sample magnetometer (VSM), and Percent diffuse reflectance spectroscopy (DR %), were used to study the physical properties. XRD peaks showed pure single phase of hexagonal ferrites and the average crystallite size varies in a range of 42.35–49.90nm. Room temperature (RT) specific magnetization (σ–H) data revealed the strong ferromagnetic nature of hexaferrite with remanant specific magnetization (σr) in the range of 29.9–34.6Am2/kg and extrapolated specific saturation magnetization (σs) in the range 53.69–67.42Am2/kg. The maximum coercive field (Hc) of 3.812×105A/m (belongs to BaFe12O19) decreases to minimum 2.177×105A/m with increasing ion substitution. Magnetic anisotropy was confirmed as uniaxial and effective anisotropy constant (Keff) takes values between 2.532×105J/m3 and 3.105×105J/m3. The anisotropy field (Ha) around 1.6T revealed that all samples are magnetically hard materials. The Tauc graphs were plotted to estimate the direct optical energy band gap (Eg) of hexaferrite. The Eg values decreased from 1.88eV to 1.69eV with increasing Bi, La, Y compositions.
•BaBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites were synthesized via sol–gel autocombustion route first time.•Room temperature (RT) specific magnetization (σ–H) data revealed the strong ferromagnetic nature of hexaferrite with remanant specific magnetization (σr) in the range of 29.9–34.6emu/g and extrapolated specific saturation magnetization (σs) in the range 53.69–67.42emu/g.•The anisotropy field (Ha) around 16,000Oe revealed that all samples are magnetically hard materials.
This study investigated the effect of Nb3+ substitution on the magnetic and structural properties of CoFe2O4 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 CoNbxFe2-xO4 were estimated to be in the range 0.48–0.53 eV for Nb3+ content x = 0.0–0.10. Magnetization measurements at room temperature (RT; 300 K) and at 10 K were performed on spinel CoNbxFe2-xO4 (0.00 ≤ x ≤ 0.10) NPs using a vibrating sample magnetometer (VSM). Nb3+ 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 (Ms) in the range 44.45 – 49.40 emu/g and remanent magnetization (Mr) in the range 12.16 – 17.90 emu/g. The coercive field (Hc) is found to be equal 936 Oe and is decreased with Nb3+ 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 Nb3+-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.
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•SrBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites have been prepared by sol-gel autocombustion.•XRD patterns show that SrBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites exhibit hexagonal ...structure.•The intrinsic coercivity (Hci) above 15000Oe reveals that all samples are magnetically hard materials.
SrBixLaxYxFe12−3xO19 (0.0≤x≤0.33) hexaferrites were produced via sol-gel auto combustion. XRD patterns show that all the samples are single-phase M-type strontium hexaferrite (SrM). The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field decreases from 4740Oe to 2720Oe with increasing ion content. In particular, SrBixLaxYxFe12−3xO19 NPs with x=0.0, 0.1, 0.2 have suitable magnetic characteristics (σs=62.03–64.72emu/g and Hc=3105–4740Oe) for magnetic recording. The intrinsic coercivity (Hci) above 15000Oe reveals that all samples are magnetically hard materials. Tauc plots were used to specify the direct optical energy band gap (Eg) of NPs. The Eg values are between 1.76eV and 1.85eV. 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, relative area and hyperfine magnetic field values on Bi3+ La3+ and Y3+ substitutions have been determined.
A simple sol-gel auto combustion process was used to synthesize La3+ substituted M-type strontium hexaferrite, Sr1-xLaxFe12-xO19 (0.0≤x≤ 0.5). Structural, magnetic, and optical behavior as a function ...of La3+ substitutions were investigated by Fourier transformed infrared spectroscopy (FT-IR). X-ray powder diffraction (XRD). Scanning electron microscopy (SEM), Mössbauer spectroscopy, vibrating sample magnetometer (VSM), and Diffuse reflectance spectroscopy (DRS). XRD data showed single phase magnetoplumbite structure and Rietveld analysis confirmed P63/mmc space group for all the series. The average crystallite size was found to be in the range of 43.2–48.4nm. The variation in line width, isomer shift, quadrupole splitting, relative area and hyperfine magnetic field values have been determined from 57Fe Mössbauer spectroscopy data. The fittings accounted for the Fe2+/Fe3+ charge compensation mechanism at the 2a site due to replacement of Sr2+ by La3+. The saturation magnetization (σs) decreases from 57,21 to 63,23emu/g and remnant magnetization (σr) decreases from 35.6emu/g to 28.7emu/g with increasing La substitution. The decrement is sharper at coercive field (Hc) from maximum value of 5325 to minimum 1825Oe. Demagnetizing factor (N) is 3 times more for the x=0.3, 0.4, and 0.5. However all samples exhibit ferromagnetic behavior at room temperature. Magnetic anisotropy of Hexaferrites was detected as uniaxial and effective anisotropy constants (Keff) were between 5.93×105 and 4.76×105 Ergs/g. The high magnitudes of anisotropy fields (Ha) in the range of 13863–15574Oe reveal that all hexaferrites are magnetic hard materials. Tauc plots were applied to extrapolate the direct optical energy band gap (Eg) of hexaferrites. The Eg values decreased from 1.83 to 1.34eV with increasing La content.
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