Formation Of Hexaferrite Research Articles

Structural, spectral, dielectric, and magnetic properties of Gd3+ substituted Y-type Barium hexaferrites

Co-precipitation method is used to prepare Mn2Ba2GdxFe12-xO22 (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) Y-type hexaferrites. X-ray diffraction patterns reviled that prepared samples have single phase. The lattice parameters of ‘a’ and ‘c’ increases from 5.87 Å to 5.89 Å and 43.50 Å to 43.68 Å with the incorporation of Gd3+ (Gadolinium), respectively. Samples crystallite sizes were in the 88.8–201 nm range. The spectrum of FTIR explains Fe-O vibrational bands, which signifies the formation of Y-type hexaferrites. The maximum quality factor ‘Q’ value is obtained at 2 GHz. The maximum Q value at high frequency suggests the potential uses of prepared samples for multilayered chip inductors operating at high frequencies. A reduction in the values of saturation magnetization (Ms), coercivity (Hc) as well as in remanence (Mr) were observed in 32.0–10.2 emu/g, 19.30–5.41 emu/g, and 3084.60–1071.3 Oe range respectively. The decrement in the squareness ratio was also found in the range of 0.594–0.529. The values of squareness ratios greater than 0.5 specify that the prepared materials have a sole magnetic domain. Due to the high coercivity of the prepared materials, these could be used in devices that use high frequencies and perpendicular recording mediums.

Impact of cobalt substitutions on optical, magnetic, dielectric, and structural, properties of BaFe11.6-xAl0.4CoxO19 hexaferrites prepared by Co-precipitation process followed by rapid sonochemical synthesis

The dielectric along with magnetic features of hexaferrites could be remarkably improved by cationic substitutions. Therefore, in the current work we synthesized cobalt substituted BaFe11.6-xAl0.4CoxO19 (0 ≤ x ≤ 1.2) hexaferrites via co-precipitation process followed by rapid sonochemical procedure. Structural analysis showed that, as the concentration of Co increased, the lattice-parameters ‘a’, ‘c’, crystallites-size, and volume increased. The SEM micrographs revealed the uniform and homogeneous distributions of particles in all samples. The two strong absorption bands indicated by FTIR analysis confirm the successful formation of M-type hexaferrites. The decreasing trend of optical band gape with cobalt doping is indicated by UV vis spectroscopy analysis. The dielectric-loss(ε''), dissipation factor, and dielectric-constant(ε′), increased as the content of cobalt is raised. The produced M-type hexaferrite exhibits increased AC electrical conductivity with frequency and doping concentration. Non-Debye-type relaxation is suggested by the cole–cole diagrams (Mʹ vs. Mʹʹ) for prepared samples. As Co concentrations increased, the magnetic moments per formula unit(mB) and saturation magnetization increased up to the optimal doping content of x = 0.9, after that these parameters showing decreasing trend. The magnetic anisotropy constant (K), coercivity (Hc), anisotropy-parameter(B), and anisotropy-field(Ha) were all showing increasing tendency with doping content. The investigations above revealed that Co replaced BaFe11.6-xAl0.4CoxO19 (0≤x ≤ 1.2) hexaferrites will be suitable for use as a permanent magnet, magnetic recording media, and other magnetic applications.

Functionalization of morphology in optimization of dielectric, electrical/impedance modulus, and relaxation mechanisms of Co-Ni doped M-type Sr nanoferrites

In this article, novel M-type hexaferrites SrCoxNixFe12−2xO19 were synthesized using the sol–gel method. The phase structure was characterized by x-ray diffraction, grain morphology was investigated from scanned electron micrographs, and dielectric/electric/impedance characteristics were analyzed in the frequency range of 100 Hz to 2 MHz. X-ray diffraction (XRD) revealed the formation of hexaferrites without any secondary phase. The grain size and distribution were significantly affected by Co-Ni dopants and there was an observation of cluster of grains, grain agglomerates, and improved inter-grain connectivity. The substitution of Co-Ni caused a reduction in crystallite size from 41.47 to 23.14 nm and the dielectric constant/loss tangent varied non-monotonically. The electric modulus indicated a non-Debye type relaxation and the charge transport mechanism exhibited conductivity relaxation to be more dominant than dielectric relaxation. The prepared ferrites show a large dielectric constant and hence are suitable for use in transformer core and storage media. The correlation of simulated grain/grain boundary parameters with morphology, dielectric parameter, and electric modulus has been presented.

Magnetic properties and coupled spin‒phonon behavior of M‒type Sr1-xSmxFe12O19 (0 ≤ x ≤ 0.15) nanoparticles

We thoroughly investigated the effects of Sm³⁺ doping on the magnetic, structural, hyperfine, and vibrational properties of Sr1-xSmxFe12O19 (0 ≤ x ≤ 0.15) nanoparticles, which were synthesized using the proteic sol-gel process. The Rietveld refined XRD patterns confirmed the presence of M-type SrFe12O19, alongside a minor fraction of α-Fe2O3. As Sm³⁺ doping increased, the unit cell volume fluctuated, decreasing from 691.73 ų at x = 0 to 690.67 ų at x = 0.10 and slightly rising thereafter. The incorporation of Sm³⁺ induced a conversion of Fe3+ to Fe2+, affecting lattice parameters and crystallinity. At x = 0.10, maximum crystallite size (56.48 nm) and X-ray density (4.83 g/cm³) were attained, alongside decreased microstrain, indicating improved crystallinity and reduced defects. However, at x = 0.15, an increase in microstrain suggested lattice instability. FTIR confirmed that bands in the range 400–600 cm⁻1 might be due to the stretching vibration of oxygen and metal (Fe–O) ions, confirming the formation of hexaferrite. Temperature-dependent Raman spectroscopy studies confirmed the presence of spin-phonon coupling in all samples in the ferrimagnetic transition at ∼725-735 K. Mössbauer spectroscopy elucidated that the substitution of Sr2+ by Sm3+ induced the most pronounced effect on the 12k, 4f2, and 2a sites, corroborating the evolution of the lattice constants and the fact that these three sites have Sr sites in their close vicinity. The room-temperature hysteresis loops exhibited narrow features, indicative of soft magnetic behavior. Saturation magnetization (Ms), remanent magnetization (Mr), and coercivity (Hc) varied with Sm3+ doping content (x). Ms initially decreased from 62.62 emu/g and 22.03 emu/g at x = 0.00 to 54.96 emu/g and 19.63 emu/g at x = 0.10, respectively, and then increase to 59.77 emu/g and 21.86 emu/g at x = 0.15. Conversely, Mr and Hc showed a non-monotonic trend with x, suggesting complex interactions between dopant concentration and magnetic properties.

Synthesis and Characterization of Barium Hexagonal Ferrite (BaFe12O19)

Barium Ferrites is a good class of electrical material due to its high resistivity. It is mainly used in electronics and telecommunication industry due to their novel electrical properties. We have synthesized barium hexagonal ferrite (BaFe12O19) by solid state reaction method. The prepared precursor was calcined at temperature 750°C and characterized by FTIR, XRD and SEM. X-ray diffraction analysis confirmed the single-phase formation of BaFe12O19. Using the Debye Scherrer formula, the crystallite size of BaFe12O19 was calculated, and the average particle sizes were 26.52 nm, 27.17 nm, 19.17 nm and 23.67 nm. The result confirms that barium ferrite powder has a constant size of less than 30 nm. Four peaks at 2θ values of 35.52, 43.22, 57.21 and 62.84 degrees, corresponding to (110) (111) (210) and (211) planes of Barium ferrite have been observed. The FTIR spectra showed important signature absorption spectra of hexaferrite at 314 cm−1, 499 cm−1 & 628 cm−1. These peaks confirm the formation of barium hexaferrites. The SEM images of barium hexaferrite at 750°C showed large number of vertically grown barium hexaferrite nanorods with a grain size between 110 nm to 130 nm. Thus, barium ferrite is a good candidate in the use of electronics and communication sector.

The study of structural, magnetic, and microwave absorbing properties of graphene/hexagonal ferrite for microwave absorber

This work reports the synthesis and characterization of Y-type Hexaferrite (Ba2Co2Fe12O22) and its composites with 20, 30, 40, and 50 wt% rGO. Ferrites were fabricated using the hydrothermal method and then sintered for 6 h at 1000 °C. The formation of Y-type hexaferrite (Ba2Co2Fe12O22) and Ferrites/rGO composites was confirmed using x-ray diffraction. Ferrite/rGO composites exhibited no diffraction peaks due to rGO, which may be due to staking disorders and uniformly dispersed graphene sheets. Scanning electron microscopy showed that graphene nanolayers are well-decorated with Y-type hexaferrite nanoparticles. FTIR spectra measured for Ba2Co2Fe12O22, rGO, and Ba2Co2Fe12O22/rGO nanocomposites revealed the presence of relevant functional chemical bonds. The dielectric properties studied between 1MHz-3GHz frequency range showed that composites of Ba2Co2Fe12O22/rGO perform better than pure ferrite. Diffuse reflectance spectroscopy was applied to determine the band gap, and rGO/Ferrites composites exhibited a band gap in the range of 4.4–4.6 eV. Vibrating sample magnetometer (VSM) measurements showed saturation magnetization of 26.2 emu g−1 in pure hexaferrite, which significantly lowered with rGO content in the composites. From enhanced absorption and reflection parameters of dielectric properties and magnetic loss that originate from the synergetic effect of rGO and Y-type hexaferrite (Ba2Co2Fe12O22), this study suggests lightweight, flexible, and efficient EMI shielding composites.

Structural, morphological, XPS, dielectric and spectral properties of sol-gel synthesized Ba–Zn–Cr U-type nanocrystalline magnetic oxide materials

Polycrystalline Cr3+ substituted Ba4Zn2Fe36-xCrxO60 (Zn2U) U-type hexaferrite compositions Ba4Zn2Fe36-xCrxO60 (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were fabricated using the sol-gel self-ignition technique. U-type hexaferrite structure was achieved by sintering the powdered samples for 6 h at 1200 °C in a muffle furnace. The phase identification and structural parameters of Zn2U hexaferrites were evaluated by X-ray diffraction peaks of the powdered samples. Lattice parameters (a,c) and unit cell volume decreased upon Cr3+ substitution. The crystallite size was measured between 61 and 57 nm. FTIR spectra revealed the existence of specific absorption (Fe–O) bands at wavenumbers 419 and 539 cm−1. These bands further verify the formation of U-type hexaferrite. SEM micrographs showed the platelet-like morphology of the grains with proper hexagonal structure. X-ray photoelectron spectroscopy (XPS) results confirmed the existence of all metal ions with their corresponding electronic states. The dielectric response of the fabricated Zn2U U-type hexaferrite pellets was investigated at room temperature through a vector network analyzer with a wide frequency band from 1 MHz to 6 GHz. Dielectric constant (εʹ) was increased for the compositions x = 1.0 and 1.5 while dielectric loss (εʺ), tangent loss (tanδ), and ac conductivity (Ϭac) were reduced upon Cr3+ substitution. Single semicircles in the impedance Cole-Cole plots revealed that grain boundaries play a vital role in the conduction process of prepared U-type hexaferrites. Microwave absorption (MW) was improved with Cr3+ substitution. The minimum reflection loss (RL) of −53dB (99.99% MW absorption) at frequency 1.3 GHz was obtained for composition x = 0.5. The dielectric analysis (low losses and high Q-values) of the prepared hexaferrites predicts their appropriate use in high-frequency device applications.

Crystal structure refinement, optical, magnetic, and X-band microwave shielding properties of Dy3+ doped Ni2Y-type strontium hexagonal ferrites

Ni2Y-type strontium hexaferrites having chemical dddof Sr1·8Ba0·2Ni2Fe12-xDyxO22 (x = 0.0, 0.1, 0.2) were made utilizing the sol-gel combustion technique. All samples' XRD patterns demonstrate the production of NiFe2O4 and Fe3O4 which are a phase that is intermediate in the synthesis of the required Ni2Y-type strontium hexaferrites. The FTIR indicates the presence of absorption peaks at about 557 and 432 cm−1, this shows the possibility of the formation of Y-type hexaferrites. UV-vis NIR spectroscopy analysis indicates that the energy band-gap of Y-type hexaferrites is affected by the increase in Dy3+ concentration. The values of the band-gap were found to be between 1.66 and 1.78 eV. According to the FESEM analysis, platelet-structure is formed with particles that range in size from 3.665 to 3.927 μm. The observed coercivity, saturation, and remnant magnetization first decreased with an increase in the concentration of Dy3+ for the sample having x = 0.1 and then increases for the sample with x = 0.2. The sample with the greatest amount of Dy3+ (i.e.x = 0.2) has a value of total shielding effectiveness of 27.5 dB. The prepared Ni2Y-type hexaferrites sample could be use for efficient shielding of microwaves in X-band.

Enhanced magnetoelectric coupling in novel rare earth metal substituted Sr based Z-hexaferrites/P(VDF-HFP) composites

This research is driven by a desire to create composite films that combine the ferrimagnetic capabilities of pure and La/Nd substituted Sr3Co2Fe24O41 Z-hexaferrites with the multifunctional features of ferroelectric polymers. A flexible magnetoelectric (ME) polymer composite films, with Sr3Co2Fe24O41 (SF), Sr2.85La0.15Co2Fe24O41(SF–La) and Sr2.85Nd0.15Co2Fe24O41 (SF-Nd) as the ferrimagnetic material and poly vinylidene fluoride-hexafluoropropylene (PH) as a ferroelectric component, were synthesized using solution casting method. In the current case, two steps have been used to synthesize ferroelectric and ferrimagnetic composites films: first, SF, SF-La and SF-Nd hexaferrite samples were synthesized using solid state reaction method and then 20% weight percentage of these hexaferrites were incorporated into the PH matrix using solution casting method to form composite film. In order to find the traces of collaborative interactions between the two phases, the structural, magnetic, and ferroelectric properties of these composite samples have been studied. The XRD data confirm the formation of SF, SF-La and SF-Nd hexaferrite dispersed in a piezoelectric copolymer PH matrix. The changes in the ferroelectric properties in different magnetic fields demonstrated the existence of ME coupling in the composite films. The inclusion of PH enhanced the magnetoelectric coupling of composite films. The maximal value of magnetoelectric coupling coefficient (αME) observed is 0.213, 1.227, 3.403 and 9.797 mV cm−1 Oe−1 for SF, PHSF, PHSF-La and PHSF-Nd, respectively. There is approximately 46-time increase in the maximum value of magnetoelectric coupling coefficient (αME) in PHSF-Nd (9.797 mV/cm.Oe) composites as compare to pure SF (0.213 mV/cm.Oe).

Exploring the structural and magnetic trends in Ba0.9Sm0.1Fe12−xAlxO19 M-type Hexaferrites

The current study describes the structural and magnetic properties of Ba0.9Sm0.1Fe12−x Al x O19 (x = 0.0, 0.5, 1.0, 2.0, 3.0) M-type hexaferrites. The conventional ceramic route was implied to prepare all the nominal samples. Morphological analysis suggested the non-presence of secondary phases as well as the formation of the hexaferrites material. X-ray Diffraction technique was used for structural analysis from which microstructural parameters are calculated and discussed. Magnetic properties are measured at room temperature. The saturation magnetization (Ms) and coercivity (Hc) values show a cyclic and converse trend for synthesized samples. Firstly, a decrease in Ms and an increase in Hc was observed up to intermediate dopant incorporation and becomes converse for higher doping levels. The maximum coercivity and minimum magnetization are observed for Ba0.9Sm0.1Fe11Al1O19. The c/a and Mr/Ms ratio suggest the formation of perfect M-type hexaferrites. This work suggests that synthesized material is a good option for magnetic applications e.g., transformer and inductor cores, microwave devices, recording heads, and magnetic shielding.

Investigation of structural, magnetic and dielectric properties of SrM/PEEK: A potential microwave absorber

The current study aims to investigate the effect of Polyether Ether Ketone (PEEK) on the structural, magnetic, and microwave properties of substituted M-type SrFe11.5Co0.5O12 (SrM) hexaferrite. Nanocomposites based on SrM/PEEK in ratios 4:0, 3:1, 2:2, and 0:4 were prepared by employing the micro-emulsion method. The composites were further characterized using XRD, SEM, FTIR, and VNA. XRD results exhibited a single-phase hexaferrite structure with an average crystallite size of 40 nm for pure SrM, which decreased due to increasing PEEK concentration. FESEM micrographs revealed the surface morphology and nature of the grains in the prepared nanocomposites. EDAX plots showed the presence of the constituent elements e.g., Fe, Sr, C, and O, at the respective standard energies. VSM results revealed the diamagnetic and ferromagnetic nature of PEEK and pure SrM/nanocomposite samples, respectively. FTIR spectra of SrM depicted the formation of hexaferrite due to the presence of Fe–O stretching peak at 525 cm−1. Reflection loss was found to decrease due to increasing ferrite concentration in PEEK. This indicates that SrM/PEEK composites are potential microwave absorbers for microwave applications in the X band.

Investigation of crystal structure, electrical and dielectric response of Zr4+ -Co2+ substituted Ba–Sr–Ni Y-type hexagonal ferrites synthesized by sol-gel route

A series of (Zr–Co) substituted Y-type polycrystalline hexaferrite with composition SrBaNi2(ZrCo)xFe12-2xO22 (x = 0.0, 0.25, 0.50, 0.75, 1.0) were fabricated by sol-gel auto combustion method. Pure Y-type single phase formation was achieved at a relatively lower temperature of 1150 °C for 5:30 h. The fabricated nano ferrites were examined by X-ray powder diffraction to confirm the pure single-phase formation of Y-type hexaferrites. An increase in lattice parameters (a& c) was observed by adding Zr4+-Co2+ metal cations. Crystallite size (D) measured in the 48-19 nm range. FTIR spectra clarified iron-oxygen vibrational bands at 417-487 cm−1, which approved the Y-type hexaferrites formation. DC electrical resistivity has an opposite trend at high and low temperatures with increasing Zr4+-Co2+ content (x). DC electrical resistivity values depend on grain size; they have an inverse relation. Activation energy, drift mobility, and Curie temperature were also determined. Conduction is due to the hopping of electrons below the Curie temperature, and polarons are responsible for hopping above the Curie temperature. Activation energy varies from 0.39 to 0.10 eV with the substitution of Zr4+-Co2+ ions. A wide frequency range of dielectric characteristics (1 MHz–6GHz) was observed, and these parameters revealed a considerable fluctuation with the substitution of Zr4+–Co2+ ions. Dielectric constant, dielectric loss and ac conductivity of nano ferrites materials increased with frequency and Zr4+-Co2+ content (x). Complex impedance spectroscopy formalism using the Cole-Cole plots indicated that most dielectric responses arise from grain boundary contributions.

Reactive flash sintering of SrFe12O19 ceramic permanent magnets

Reactive flash-sintering technique has been used in order to obtain strontium ferrite magnets from a mixture of SrCO3 and Fe2O3 commercial powders. This technique allows preparing sintered SrFe12O19 at a furnace temperature of just 973 K during just 2 min by applying a modest field of 40 V cm-1, instead of the conventional sintering process employed in ferrite magnet manufacturing that demands high temperature and long dwell times. Analysis of structural and magnetic properties were performed as a function of time in which the flash event was held. Mössbauer spectra show the existence of five different kinds of local environments, confirming the formation of strontium hexaferrite. The resulting samples exhibit comparable magnetic properties to the state-of-the-art ferrite magnets. In particular, produced samples reach a coercivity of 0.4 T and a specific saturation magnetization of 70 Am2 kg-1.

Effect of Heat Treatment on the Structural and Magnetic properties of Sr1-x Fe12-y Cox Aly O19

Hexaferrites have recently fascinated researcher’s interest due to their broad range of uses, including permanent magnets, magnetic storage media, wireless telecommunication and microwave application. In this work Sr1-x Fe12-y Cox Aly O19(x=0.2, y=0.2) was synthesized by using the sol gel auto combustion method and sintered for 5 hours at different temperatures ranging from 800°C to 1100°C. The formation of M-type hexaferrites has been confirmed by XRD analysis. The appearance of three major peaks i.e., 432cm-1,547cm-1,594-1 in the FTIR spectra between 400 cm-1 and 600 cm-1 indicates the existence of M-type hexagonal ferrites. FESEM shows plate like hexagonal shaped grains. The temperature at which hexaferrite was obtained determined by TGA analysis. The M-H loop derived from the vibrating sample magnetometer was used to compute magnetic parameter.

Structural, magnetic, and photocatalytic investigation of Hexaferrites/PANI nanocomposites

A1-xSmxFe12-xCoxO19 (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanoparticles were prepared via sol-gel auto combustion meanwhile A1-xSmxFe12-xCoxO19/PANI (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanocomposites were synthesized by in situ polymerization. In order to achieve the required hexagonal and PANI structure, fourier transform infrared spectroscopy (FTIR) were manipulated. The bands at 400 and 500 cm−1 wavenumbers confirmed the formation of hexaferrites in all samples while two bands at 1463 and 1554 cm−1 wavenumber represented the existence of quinoid and benzenoid rings in A1-xSmxFe12-xCoxO19/PANI (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanocomposites. The X-ray diffraction spectroscopy (XRD) is in exact accordance with JCPDS No. 01-072-073 for Ba1-xSmxFe12-xCoxO19 (x = 0.03, 0.05, 0.07) and No. 00-024-1207 for Sr1-xSmxFe12-xCoxO19 (x = 0.03, 0.05, 0.07). The arising two novel peaks at 20 and 25° was the evidence for the PANI structure beside Ba and Sr hexaferrites peaks in A1-xSmxFe12-xCoxO19/PANI (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanocomposites. Field emission scanning electron microscopy (FESEM) of A1-xSmxFe12-xCoxO19 (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanoparticles indicated the complete hexagonal structure of hexaferrites. In A1-xSmxFe12-xCoxO19/PANI (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanocomposites the sphere particles of PANI covered the unabridged hexagonal shape of hexaferrites. The magnetic properties of products were measured by vibrating sample magnetometer (VSM). The saturation magnetization of A1-xSmxFe12-xCoxO19 (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanoparticles modified erratically. By adding non-magnetic PANI, the saturation magnetization decreased. The photocatalytic properties of A1-xSmxFe12-xCoxO19 (A = Ba, Sr, and x = 0.03, 0.05, 0.07) nanoparticles revealed that insertion of rare earth increased the photodegradation of methylene blue, while polymerization promoted the degradation process in A1-xSmxFe12-xCoxO19/PANI (A = Ba, Sr, and x = 0.03, 0.05, 0.07).

A comprehensive study of structure, oxygen vacancy, and electrical properties of Mg2+ introduced in barium hexaferrite synthesized via spark plasma sintering

Barium hexaferrite BaFe12O19 (BFO) was prepared following conventional solid-state reaction procedure (CSRP) and its’ reformed compound has been prepared following CSRP and spark plasma sintering (SPS) approaches. The Rietveld refinement of synchrotron x-ray diffraction (SXRD) study assured single-phase formation of hexaferrite (M-type with space-group P63/mmc). A dense microstructure appeared in the SPS prepared sample compared to the other compounds. The presence of multiple valances of Fe (Fe2+ along with Fe3+) was studied following modified Mohr’s salt titration (MST) besides of oxygen vacancy estimation. Mg-doped increased oxygen vacancy amount via enhancing Fe2+ in the sample. As a result, the impedance was lower in the Mg-doped BFO (BFMO) samples in contrast to undoped sample, where SPS BFMO further reduced impedance.

Study of structural, morphological, optical bandgap and Urbach's tail of Ni2+ substituted Co2Y-type strontium hexaferrite

This study synthesize Co2Y hexaferrite Sr2NixCo2-xFe12O22 (x = 0.0, 0.2, and 0.4) applying sol–gel auto combustion annealed at 1150 0C for six hours. XRD analysis revealed a single Y-type, and the substitution of Ni2+ increased the lattice parameters and decreased crystallize size. In FTIR analysis, the formation of hexaferrite is by peaks at 449 and 557 cm-1. As shown by morphological analysis, magnetic contact results in an agglomeration of grains. The EDX spectrum identifies all hosts and substituted elements, confirming the samples' purity and stoichiometry. Further investigation of the band gap's dependency on Ni2+content is from UV–Vis spectra, which indicated bandgap energies between 2.11 and 2.17 eV.

Influence of Mn2+-substitution on the structural, morphological and magnetic properties of Co2Y strontium hexaferrites

This research focus on using sol-gel auto combustion method to synthesize Co2Y strontium hexaferrite with chemical composition Sr2MnXCo2-xFe12O22 (x = 0.0, 0.5, 1.0). Samples were calcinated at 1150 for 6 h. The XRD analysis revealed a single crystalline phase Co2Y strontium hexaferrites with the absence of secondary phase or impurity. Values of lattice parameters as well as unit cell volume rise with addition of Mn2+. The emergence of two peaks at 422 and 580 cm−1 in FTIR analysis suggests the formation of hexaferrites. The morphological analysis show an agglomerated network of grains which is caused by magnetic interaction. EDX spectra shows the entire host as well as substituted elements, this confirm the purity and stoichiometry of the prepared Co2Y strontium hexaferrites samples. Magnetic parameters: coercivity, saturation magnetization, squareness ratio as well as remnant were calculated using M-H hysteresis loop obtained from the VSM.

Crystal-structure analysis, Raman spectroscopy, dielectric measurements, magnetic and optical properties of Cr3+–Ni2+-substituted Co2Y-type barium hexaferrites

The Co2Y-type barium hexaferrite Ba2−2xCrxNixCo2Fe12O22 (x = 0.0, 0.1, 0.15) was synthesized using the sol–gel auto-combustion technique. The formation phase of the Y-type hexaferrites was observed using X-ray diffraction (XRD) analysis. Fourier-transform infrared (FTIR) analysis confirms the formation of Y-type hexaferrites. Field-emission scanning electron microscopy (FESEM) reveals particles with hexagonal plate-like morphologies. The optical band gap of the prepared samples lies between 0.74 and 2.16 eV. The coercivity values of the prepared samples demonstrate their soft-magnetic nature. Dielectric analyses show the influence of the dopant ions on the dielectric parameters of the prepared samples. Impedance spectroscopy using a Nyquist plot shows that most of the dielectric response results from grain-boundary contributions.

Investigation of crystal structure, dielectric response and magnetic properties of Tb3+ substituted Co2 Y-type barium hexaferrites

Y-type hexaferrites powder samples of Ba1·8Sr0·2Co2Fe12-xTbxO22 (with x = 0.0, 0.1, and 0.2) were prepared by the method of sol-gel auto combustion. XRD and Rietveld refinement analysis shows that the prepared Y-type hexaferrites samples exhibit pure crystalline phase with the absence of impurity. FTIR study gives an idea of the formation of Y-type hexaferrites by the appearance of three characteristics bands at 409, 433, and 552 cm−1. FESEM analysis shows plate-like morphology with the presence of all hosts and substituted elements observed in the EDX spectra and mapping. The grain size decreases with increase in the concentration of Tb3+, the particle size was observed to be in the range 56.48–58.54 nm. Typical dielectric response of ferrites was observed in the dielectric analysis. Cole-Cole plot shows that the contribution of grain is negligible compared to grain boundaries contribution. The multi domain magnetic nature of the prepared Y-type hexaferrite samples resulted in domain wall displacement and consequently influences the values of the coercivity.