Single-phase M-type hexagonal ferrites, SrBixFe12−xO19 (0.0≤x≤1.0), were prepared by a co-precipitation assisted ceramic route. The influence of the Bi3+ substitution on the crystallization of ...ferrite phase has been examined using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Mössbauer spectroscopy. The XRD data show that the nanoparticles crystallize in the single hexagonal magnetoplumbite phase with the crystallite size varying between 65 and 82nm. A systematic change in the lattice constants, a=b and c, was observed because of the ionic radius of Bi3+ (1.17Å) being larger than that of Fe3+ ion (0.64Å). SEM analysis indicated the hexagonal shape morphology of products. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on Bi substitutions have been determined.
Cu1−xZnxFe2O4/SiO2 (CZF/SiO2) (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) nanocomposites were synthesized by a citric acid assisted sol–gel process and a modified Stöber method. Particle formation and evolution ...of the structural, morphological, optical and magnetic properties were investigated by Thermal analysis (TGA), X-ray powder diffractometry (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM)), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectra (DRS), and magnetic susceptibility measurements (VSM). Optical properties of Cu–Zn ferrite nanoparticles (NPs) were improved by using silica (SiO2) shell. CZF/SiO2 nanocomposites were evaluated for their magnetic and optical characteristics. The direct optical band gap (Eg) value was calculated as 1.70eV. The Eg of CZF/SiO2 nanocomposites is found to increase as the Zn content rises. Moreover, silica coating enhances the band gap of the nanocomposites. These properties of CZF/SiO2 nanocomposites make them promising candidates for magneto-optical nano-device applications.
•Mn0.5Zn0.5DyxFe2−xO4 (x ≤ 0.03) nanoparticles (NPs) were prepared by using ultrasonic irradiation.•All samples exhibit superparamagnetic properties at room temperature.•Magnetization parameters ...significantly increase due to coordination of Dy3+ rare earth ions.•ZFC-FC magnetization indicated the collective freezing of system and spin-glass-like phase.•AC susceptibility proved the spin-glass behavior of samples at low temperatures.
Mn0.5Zn0.5DyxFe2−xO4 (x ≤ 0.03) nanoparticles (NPs) were fabricated by using Ultrasonic irradiation using UZ SONOPULS HD 2070 ultrasonic homogenizer (frequency of 20 kHz and power of 70 W). Structural and morphological analyses were performed via XRD (X-ray powder diffractometer), TEM (Transmission electron microscopy) and SEM (Scanning electron microscopy). XRD presented the formation of Mn-Zn ferrite with average crystal size in 11 to 18 nm range. Direct optical energy band gaps (Eg) were specified applying diffuse reflectance investigations. Eg values are in a small band range of 1.61–1.67 eV. Low (10 K) and room temperature VSM data were recorded applying ±90 kOe external magnetic field. All samples exhibit superparamagnetic properties at RT. Magnetization parameters significantly increase due to coordination of Dy3+ rare earth ions. Magnetic moment per molecule (nB) increases from 0.952 μB to 1.137 μB and from 2.312 μB to 2.547 μB at RT and at 10 K data respectively. 10 K coercivity (Hc) values decrease from 260 Oe to 43 Oe. All samples have squareness ratios (SQR) of 0.231–0.400 range assigning the multi-domain structure at 10 K. ZFC-FC magnetization curves that were registered for two selected samples exhibit a divergence and a sharp drop below their Tpeak positions. This event is typically correlated to the collective freezing of system and spin-glass-like phase. Real part AC susceptibility data slightly shift toward high temperature regions with increasing frequencies. Critical Slowing Down (CSD) model explained the spin dynamics of interacting NPs consistently with literature and proved the spin-glass behavior of samples at low temperatures.
Thiolated polymers are commonly preferred for biomedical applications with their good permeation properties providing them higher bioavailability. However, the thiolation process is mostly ...time-consuming series of chemical reactions. This study describes a simple irreversible thiol group integration to the pectin hydrogels by noncovalent bonding. We used 2-thiobarbituric acid (TBA) for thiolation. We proved with full-atom molecular dynamics simulations and experimental methods that TBA desertion is negligible. Pectin hydrogels become more flexible and their disintegration is delayed from 4 h up to four days with TBA addition. Also, hydrogels can successfully deliver the model drug, theophylline, showing a controlled release profile.
Some new types of Ce3+ and Dy3+ co-doped manganese-zinc nanospinel ferrites (CDMZNSFs) of the form (Mn0.5Zn0.5)Fe2-2xCexDyxO4 (with 0.0 ≤ x ≤ 0.1) were sonochemically produced and characterized. The ...structure, morphology, optical and magnetic properties of these NSFs were determined as a function of co-dopant (Ce3+ and Dy3+) contents. The direct optical band gap energies of the studied NSFs were ranged from 1.54 to 1.85 eV. The measurements of magnetization versus magnetic field of the prepared NSFs disclosed a superparamagnetic (SPM) behavior at room temperature (RT). The measurements of temperature-dependent magnetizations revealed a transition from superparamagnetic (SPM) state above blocking temperature TB to a ferromagnetic (FM) state below TB. The saturation magnetization and TB decreased with the increase in co-dopant contents. In addition, the bactericidal (on the gram-positive and gram-negative bacterial strains) and anti-cancerous effectiveness of these NSFs were assessed. The cancer cells' growth inhibitory action of these NSFs was tested against both normal (HEK-293) and cancerous (HCT-116) human cells. After 48 h of treatment of the cancerous cells with the NSFs, their population was significantly dropped as shown by the MTT assay, indicating the selective inhibition of the cancer cells growth by the proposed NSFs. Conversely, the non-cancerous cells (HEK-293) population remained unaffected. The IC50 values of the NSFs-treated cancerous cells (HCT-116) were in the range of 0.74–2.35 µg/mL. The results of the MIC and MBC assays revealed the reasonable antibacterial efficacy (growth inhibitory activity) of these NSFs when tested against the E. coli and S. aureus bacterial strains. It is established that the proposed Ce3+/Dy3+ co-activated CDMZNSFs may be beneficial for the anti-cancerous and bactericidal applications.
•Dy3+ and Y3+ ions co-doped Zn0.5Mn0.5Fe2O4(ZMDyYFe) (x = 0.00–0.05) nanospinel ferrites were synthesized sonochemically.•Direct optical energy band gaps (Eg) were extracted from tauc plots. Eg ...values existed in a narrow range of 1.64 - 1.74 eV.•M(H) investigations exhibited the superparamagnetic behavior at RT and ferrimagnetic behavior at 10 K for synthesized samples.
Dy3+ and Y3+ ions co-doped Zn0.5Mn0.5Fe2O4(ZMDyYFe) (x = 0.00–0.05) nanospinel ferrite nanoparticles (SFNPs) have been synthesized through an ultrasonication approach. The rare earth co-doping with Dy3+ and Y3+ ions was applied to tune the structural and magnetic properties of the ZnMn spinel ferrites. The influence of the co-doped of both Dy3+ and Y3+ ions on the structural, optical, and magnetic characteristics of Zn0.5Mn0.5Fe2O4 SFNPs was analyzed in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), high- resolution tunneling electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), and elemental mappings. XRD results revealed the formation of the spinel phases and the structural changes which were accompanied the Dy3+ and Y3+ ions co-doping. The cubic spinel phase of all samples has been confirmed by the application of Rietveld refinement. As the value of ``x`` increased up to x = 0.04, the lattice constant was found to increase from 8.401 to 8.408 Å and the size of the crystallites was calculated to be in the range 7.26 nm-11.10 nm. HR-SEM and HR-TEM micrographs also presented the cubic morphology of the products. Diffuse reflectance spectroscopy (DRS) measurements were done on pure and Dy3+ and Y3+ co-doped Mn0.5Zn0.5Fe2O4 SFNPs. Direct band gaps (Eg) were extracted from Tauc plots. Eg values existed in a narrow range between 1.64 eV and 1.74 eV. Magnetic investigations exhibited the superparamagnetic behavior at RT (room temperature) and ferrimagnetic behavior at 10 K for synthesized samples. At RT analyzes, undoped Mn0.5Zn0.5Fe2O4 SFNPs had the maximum saturation magnetization (MS) of 34.84 emu/g and magneton number (nB) of 1.47 μB. An inverse proportion with the increasing ion ratio were observed among those parameters. The 10 K magnetization data revealed that co-doped Mn0.5Zn0.5Dy0.02Y0.02Fe1.96O4 SFNPs had magnetic parameters of MS,max= 67.39 emu/g, nB,max = 2.88 μB and HC,max = 574 Oe (HC: coercivity and max: maximum). Among the rest of the co-doped samples, MS and nB data had a similar negative trend with respect to the increasing ion ratio including the remnant magnetizations (Mr). The rest of the HC values were found to be between 275 Oe and 361 Oe. Squareness ratios (SQRs= Mr/MS) had a range of 0.181- 0.321 and confirmed the multi-domain wall structure for all SFNPs at 10 K. The maximum value of effective crystal anisotropy constant (Keff) 6.04 × 104 Erg/g belongs to Mn0.5Zn0.5Dy0.02Y0.02Fe1.96O4 SFNPs, and others have the same order of 104 Erg/g for Keff constants. Although this sample has the largest internal anisotropy field (Ha) of 1794 Oe, it can also be classified as a soft magnetic material like other nanoparticle samples. The Dy3+ and Y3+ ions co-doped ZMDyYFe (x = 0.00–0.05) SFNPs, with varying structural and magnetic properties, can have potential applications in various areas such as magnetic switching, security, magnetic core, microwave absorption applications, nanofabrication and nanodevices.
Cu
2+
ion substituted nanocrystalline BaFe
12
O
19
Ba
1 − x
Cu
x
Fe
12
O
19
(0.0 ≤ x ≤ 0.5) hexaferrite powders were synthesized by sol–gel combustion route and its effects on structure, morphology ...and magnetic properties of barium hexaferrite (BaFe
12
O
19
) were presented. X-Ray Powder Diffraction (XRD), Scanning Electron Microscopy (HR-SEM), Transmission Electron Microscopy (HR-TEM) and Fourier Transform Infrared (FT-IR) analyses revealed the M-type hexagonal structure of all samples. Vibrating sample magnetometer (VSM) analyses showed that all samples have strong ferromagnetic behavior at room temperature. The crystallite size varies in a range of 23.30–35.12 nm. Both HR-SEM and HR-TEM analyses confirmed the hexagonal morphology for products. A minimum of 40.49 and a maximum of 54.36 emu/g estimated specific saturation magnetization (σ
s
) were observed for Ba
0.5
Cu
0.5
Fe
12
O
19
and Ba
0.9
Cu
0.1
Fe
12
O
19
NPs, respectively. The remnant magnetization (σ
r
) has a minimum value of 21.27 emu/g belonging to Ba
0.5
Cu
0.5
Fe
12
O
19
and has a maximum value of 28.15 emu/g belonging to Ba
0.7
Cu
0.3
Fe
12
O
19
NPs. The coercive fields are between 1726 Oe and 2853 Oe.
K
eff
(calculated effective anisotropy constants) is changing from 2.31 × 10
5
to 3.23 × 10
5
Ergs/g. It was observed that the strong magneto-crystalline anisotropy fields, (
H
a
) above 11.0 kOe for all samples which confirmed that all samples are hard magnet. Due to their small crystallite size (smaller than 50 nm) and high saturation magnetization, Ba
1 − x
Cu
x
Fe
12
O
19
(0.0 ≤ x ≤ 0.5) nanoparticles can be employed as magnetic recording materials.
In this study, the structural, morphological, and magnetic properties of hydrothermally synthesized Co0.5Ni0.5BixFe2-xO4(x=0.00–0.10)nanosized spinel ferrites,(CoNiBiFO (x=0.00–0.10) NSFs), were ...investigated. The formation of CoNiBiFO NSFs phase was confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the morphology of the NSFs. Magnetization revealed that undoped Co0.5Ni0.5Fe2O4 and Co0.5Ni0.5BixFe2-xO4NSFs (except with x = 0.04) exhibit ferrimagnetic magnetism at 300 K. Only the hysteresis loops recorded from Co0.5Ni0.5Bi0.04Fe1.96O4NSFs have superparamagnetic characteristics. Mixed Co0.5Ni0.5Fe2O4NSFs have maximum remnant magnetization (Mr) of 23.5 emu/g, maximum saturation magnetization (MS) of 63.38 emu/g, and maximum magneton number (nB) 2.66 μB. However, Co0.5Ni0.5Bi0.04Fe1.96O4NSFs have minimum MS of 28.25 emu/g and minimum nB as 1.22 μB among Bi3+ doped and undoped samples. The coercivity (HC) of undoped Co0.5Ni0.5Fe2O4NSFs is 656 Oe. However, the Bi3+ ion-doped samples have a wide range of HC values between 101 Oe and 1038 Oe. The squareness ratios are in the range of 0.092–0.418 and multi-domain structure is assigned for all types of samples. The measured positive exchange bias (HE) magnitudes are 268 Oe and 290 Oe, respectively. Hysteresis loops recorded at 10 K proved that the products are ferrimagnetic. These coercivities showed that all the samples are magnetically harder at low temperatures. Positive HE values of 165 Oe and 297 Oe were measured from the nanoparticles (NPs) with x = 0.08 and x = 0.10 at 10 K. The SQR of the Co0.5Ni0.5Bi0.04Fe1.96O4 sample at 10 K is almost equal to the critical value of 0.5, and a single domain structure with uniaxial symmetry can be attributed for this sample. The other samples have SQRs in the range of 0.632–0.782 and multi-domain wall structure is assigned for them at 10 K.
•CoZr and NiZr substituted Sr hexaferrites were prepared via sonochemical approach.•SrCoZr and SrNiZr HFs exhibit hard ferrimagnetic behaviors at T = 300 and 10 K.•Ms, Mr and nB values increase ...initially for lower CoZr content and then decrease.•Magnetic parameters decrease with increasing NiZr content.•Density functional theory calculations were performed.
This work investigates a comparative study between Ni-Zr and Co-Zr substituted Sr-hexaferrites (HFs). SrCoxZrxFe12−2xO19 HFs (denoted as SrCoZr HFs) and SrNixZrxFe12−2xO19 HFs (denoted as SrNiZr HFs) were fabricated via sonochemical approach. X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and high-resolution transmission electron microscopy (HR-TEM) analyses revealed the creation of M-type hexaferrites. The hexagonal-platelet shape is observed by scanning electron microscopy (SEM). The total energy calculations were performed via density functional theory (DFT) on model systems representing the synthesized structures to determine their structural and magnetic properties. The magnetic properties of various synthesized SrCoZr and SrNiZr HFs were evaluated at (RT; T = 300 K) and (T = 10 K). The Ms (saturation magnetization), Mr (remanence), Hc (coercivity), SQR = Mr/Ms (squareness ratio) and nB (magnetic moment) were determined. M-H hysteresis loops of various products revealed their hard ferrimagnetic (FM) nature at RT and 10 K. Lower Co-Zr co-substitution contents (x ≤ 0.04) were discerned to reinforce the magnetic traits of the resultant Sr hexaferrite significantly when compared to the pristine (x = 0.0) one. However, the Ni-Zr co-substitution in Sr HFs provoke a reduction of magnetic parameters.
The crystal structure and magnetic properties of SrNb
x
Fe
12–
x
O
19
(0.00 ≤
x
≤ 0.08) nanohexaferrites (NHFs) fabricated using a sol–gel technique is presented in this study. The X-ray powder ...diffractometry (XRD) and Infrared spectroscopy (FT-IR) confirmed the formation of M-type hexaferrite phase. The analyses of magnetization versus applied magnetic field, M(H), were performed at room (300 K; RT) and low (10 K) temperatures. The Bohr magneton number (
n
B
), saturation (
M
s
) and remanent (
M
r
) magnetization values increase slightly with increasing Nb
3+
content. The room-temperature values of the magnetic parameters
M
r
= 31.41–33.28 emu/g,
M
s
= 57.10–60.14 emu/g and coercivity (
H
c
) between 4274 and 4540 Oe, at 10 K, magnetization data were detected that are much higher with respect to RT values:
M
r
= 45.96–51.06 emu/g,
M
s
= 94.42–95.99 emu/g. The magnetic results indicate that the samples are magnetically hard materials at both considered temperatures. The squareness ratio (SQR) is found to be around 0.50, implying single-domain NPs with uniaxial anisotropy for pristine and substituted samples. With exception, the x = 0.0 sample indicated the formation of multi-domain structure with uniaxial anisotropy at 10 K. Field cooling (FC) susceptibility measurements were applied in temperature range of 5–350 K for pristine sample and samples that contained some Nb
3+
ions. The analyses of
dc
susceptibility data also proved that Nb
3+
ion substitution increases the magnetization and, additionally, allows for an easier alignment of the magnetic domains. The obtained magnetic results were investigated deeply with relation to structural and microstructural properties. The observed remanent magnetization (
M
r
) and coercivity (
H
c
) render the products are useful for permanent magnets and high-density recording media.
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