This work investigated the effect of dysprosium (Dy) ions on the structural, microstructural and magnetic properties of nickel nanospinelferrite, NiFe2O4. The nanoparticles (NPs) of NiDyxFe2–xO4 ...(0.0 ≤ x ≤ 0.1) were prepared via the hydrothermal method. The formation of cubic phase of Ni nanoferrite was confirmed through X-ray diffraction, field emission scanning and transmission electron microscopy. Moreover, the magnetic properties of NiDyxFe2–xO4 (0.01 ≤ x ≤ 0.10) NPs were discussed. The magnetization versus field, M(H) curves exhibit super paramagnetic nature at room temperature and ferrimagnetic nature at low temperature (10 K). A noticeable improvement in the different deduced magnetic parameters is obtained especially for the NiDy0.07Fe1.93O4(x = 0.07) product. The obtained result is mostly derived from the substitution of Fe3+ ions of smaller ionic radii with Dy3+ ions of larger ionic radii that will strengthen the super exchange interactions among nanoparticles. The calculated squareness ratios are found to be much less than 0.5, due to the effect of spin disorder in the surface regions of NiDyxFe2–xO4 (0.01 ≤ x ≤ 0.10) NPs. The Dy3+ ions substitution increases the magnetic hardness (higher values of remanence Mr, coercivity Hc, and magnetic moment nB) of nickel nanoferrite samples.
In this paper, we examined the influence of dysprosium (Dy) on the structural, microstructural and magnetic properties of nickel nano spinel ferrite synthesized via the hydrothermal method. The magnetization versus field, M(H) curves exhibit superparamagnetic nature at room temperature and ferrimagnetic nature at low temperature (10 K). A noticeable improvement in the different deduced magnetic parameters is obtained especially for the NiDy0.07Fe1.93O4 (x = 0.07) product. Display omitted
Series of SrNbxYxFe12-2xO19 (0.00 ≤ x ≤ 0.05) hexaferrites (HFs) were fabricated via citrate sol-gel approach. Structural and magneto-optical properties of ensembles were investigated in detail. The ...structural and morphological analyses revealed the formation of M-type Sr hexaferrite nanoparticles. Diffuse reflectance data were registered to estimate the direct optical energy band gaps (Eg) in a range of 1.77 eV-1.87 eV. Room temperature (RT, 300 K) and low temperature (10 K) magnetic hysteresis curves were recorded by enforcing applied dc magnetic field up to ±70 kOe. Magnetic parameters were significantly tuned due to coordination of Nb3+ and Y3+ rare earth ions. Specified magnetic data reveal the strong ferromagnetic characteristics of pristine SrFe12O19 and co-doped HFs with Nb3+ and Y3+ ions at both temperatures. RT squareness ratio (SQR) has an exception only for pristine sample as 0.506, which is in the margin of theoretical limit assigning the single-domain nature with uniaxial anisotropy. However, all co-doped samples have SQR = 0.288–0.485 values that are smaller than theoretical limit of 0.50, implying multi-domain nature at RT and at 10 K. Co-doped ions cause lowering in super-exchange interactions between different sites and resulting the decrements of intrinsic magneto-crystalline anisotropy and coercivity fields. The specified magnetic characteristics make our fabricated SrNbxYxFe12-2xO19 (0.00 ≤ x ≤ 0.05) HFs good candidates as permanent magnets applications and high-density recording media.
The current study investigates the impact of vanadium substitution on the structural, magnetic, and optical properties of NiFe
2−
x
V
x
O
4
(
x
≤ 0.3) nanoparticles (NPs) produced by the ...cost-effective sol-gel route. The as-prepared spinel ceramic powders were examined by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The functional groups, spinel phase, and crystal structure were confirmed by XRD and FT-IR, respectively. The crystallites size decreased from 45.24 to 36.56 nm as the doping process increases. The plots of Tauc were drawn to determine optical band gap magnitudes of 1.291, 1.302, and 1.312 eV for
x
= 0.0, 0.2, and 0.3, respectively. The estimated saturation magnetization is maximum for pristine NiFe
2
O
4
NPs and decreases to minimum for NiFe
1.7
V
0.3
O
4
NPs. The
σ
-
H
hysteresis loops have finite coercivity (between 125 and 169 Oe) and retentivity (between 9.36 and 14.04 emu/g) values. The calculated
σ
r
/
σ
s
ratios are lower than 0.500, assigning the uniaxial anisotropy for NiFe
2−
x
V
x
O
4
. The effective anisotropy constants (
K
eff
) are in the range of 0.824 × 10
5
and 1.303 × 10
5
Erg/g. The magnetocrystalline anisotropy field (
H
a
) values are around 5.0 kOe. The characteristics of hysteresis (
σ
-
H
) curves and the order of magnetic data reveal the soft ferrimagnetic feature of as-prepared nanoparticle samples. From Mossbauer analysis, the variations in hyperfine magnetic field, quadrupole splitting, line width, and isomer shift have been evaluated. The distribution of cations showed that the octahedral B sites are occupied by all the ions of V
3+
. Mossbauer spectra are composed of four Zeeman sextets and one doublet.
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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•BaCrxFe12−xO19 (0.0 ≤ x ≤ 1.0) hexaferrites via sol–gel auto combustion method.•BaCrxFe12−xO19 (0.0 ≤ x ≤ 1.0) hexaferrites may be used for microwave devices.•BaCrxFe12−xO19 (0.0 ≤ x ≤ 1.0) ...hexaferrites may be used for magnetic recording media.
In this study, nanocrystalline BaCryFe12−yO19 (0.0 ≤ y ≤ 1.0) hexaferrite powders were prepared by sol–gel auto combustion method and the effect of Cr3+ ion substitution on morphology, structure, optic and magnetic properties of Barium hexaferrite were investigated. X-ray powder diffraction (XRD) analyses confirmed the purity of all samples. The XRD data shows that the average crystallite size lies between 60.95 nm and 50.10 nm and same was confirmed by Transmission electron microscopy. Transmission electron and scanning electron microscopy analyses presented the hexagonal morphology of all products. The characteristic hysteresis (σ-H) curves proved the ferromagnetic feature of as grown nanoparticle samples. Specific saturation magnetization (σs) drops from 46.59 to 34.89 emu/g with increasing Cr content while the coercive field values lie between 770 and 1652 Oe. The large magnitude of the magnetocrystalline (intrinsic) anisotropy field, (Ha) between 11.0 and 12.6 kOe proves that all products are magnetically hard. The energy band gap values decrease from 2.0 eV to 1.84 eV with increasing Cr content. From 57Fe Mössbauer spectroscopy, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values were determined and discussed.
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.
•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.
This study explored the microstructural and magnetic features of NiFe
2−
x
Dy
x
O
4
(
x
≤ 0.10) NPs (nanoparticles) that were synthesized by sol–gel auto-combustion method. The single phase of ...spinel ferrite has been verified for all samples without any impurity. The cubic morphology of the products was also showed by SEM. Room temperature (300 K) and 10 K magnetization curves were recorded applying a dc magnetic field up to ±50 kOe and it was observed that magnetic features of NiFe
2
O
4
NPs significantly changed by the substitution of Dy
3+
ion. Magnetization measurements showed low order of 300 and 10 K magnetic parameters (such as
K
eff
, coercivity and anisotropy field values), revealing soft ferrimagnetic behaviors of all pristine and doped NiDy
x
Fe
2−
x
O
4
(0.00 ≤
x
≤ 0.10) NPs at both 300 and 10 K. Pristine NiFe
2
O
4
has maximum magnetic moment and saturation magnetization values among all samples. Dy
3+
substitution showed a slight decrement in magnetization values compared with pristine sample. A slight increase in coercivity was noticed with Dy
3+
substitution. Squareness ratios (SQRs) have a range between 0.144 and 0.324. These values are smaller than the theoretical limit of 0.50, implying the multi-domain nature for NPs. Blocking temperature (
T
B
) was calculated as 28 K for NiFe
2
O
4
NPs.
Pure phase of NiDy
x
Fe
2−
x
O
4
(0.00 ≤
x
≤ 0.10) nanoparticles were prepared via sol–gel auto-combustion process. The structure, morphology, and magnetic properties were investigated.
Highlights
NiFe
2−
x
Dy
x
O
4
(
x
≤ 0.10) NPs were prepared via sol–gel auto-combustion method.
XRD analysis indicates the formation of pure single phase of spinel ferrites.
NiFe
2−
x
Dy
x
O
4
(
x
≤ 0.10
)
NPs exhibit soft ferrimagnetic nature.
All prepared NiFe
2−
x
Dy
x
O
4
(
x
≤ 0.10) NPs displayed a multi-domain nature.
Blocking temperature (
T
B
) was calculated as 28 K for NiFe
2
O
4
NPs.
In this study, various Co0.5Ni0.5BixFe2-xO4 (x ≤ 0.10) spinel ferrite nanofibers (CoNiBi SFNFs) have been synthesized by electrospinning technique. The structure, morphological, and magnetic features ...of CoNiBi SFNFs was investigated. XRD analysis demonstrated the formation of single-phase cubic spinel structure for all samples. The cell parameter is increasing with the increase of Bi3+ content. The cubic morphology of all products was also verified by SEM and TEM microscopies. Mössbauer analysis was used to determine the hyperfine parameters by fitting room temperature mosspectra. The Bi3+ ions occupy mainly the B site. Vibrating sample magnetometry (VSM) was applied to get magnetic data for CoNiBi SFNFs at 300 and 10 K. The characteristics of the recorded magnetic hysteresis curves revealed the existence of just ferrimagnetic phases for all fabricated spinel nanofiber samples at both temperatures. The remanent magnetization Mr, saturation magnetization MS, magnetic moment per formula nB, coercivity Hc have been determined. Bi3+ ion substitution commonly diminishes the magnetic data except the content of x = 0.04. The maximum and minimum magnitude of magnetic parameters belong to Co0.5Ni0.5Bi0.04Fe1.96O4 and Co0.5Ni0.5Bi0.10Fe1.90O4SFNFs, respectively. Pristine Co0.5Ni0.5Fe2O4 and Bi3+ ion doped samples exhibit soft magnetic at 300 K and hard magnetic nature at 10K conditions. Squareness ratio (SQR = Mr/Ms) provided extra information about the domain structure of fabricated nanofiber samples. At 10K conditions, SQR of the sample Co0.5Ni0.5Bi0.04Fe1.96O4 is almost equal to 0.5 and this critical value is assigned to the formation of single domains with uniaxial symmetry for this nanofiber. This one only and all others have SQRs that are much lower (0.073–0.366) at 300K or higher (0.620–0.781) at 10K. Those ranges specify the multi-domain wall structure for samples.
•Spinel ferrite nanofibers (CoNiBi SFNFs) have been synthesized by electrospinning technique.•Mössbauer spectra revealed the Bi3+ ions occupy mainly the B site.•The magnetization measurements at variable magnetic field (M − H) disclosed ferrimagnetic phases at 300 and 10 K.
