Applications In Recording Media Research Articles

Enhancing the magnetization, dielectric parameters and elastic parameters while simultaneously minimizing coercivity and dielectric loss in nickel-manganese-cobalt ferrite nanoparticles through Ce3+ doping assistance

This study focuses on examining how the rare-earth cerium incorporation affects the magnetic, dielectric, and mechanical characteristics of Ni0.5Mn0.25Co0.25CexFe2-xO4 spinel ferrite nanoparticles. (NMCCF). The nanoferrite Ni0.5Mn0.25Co0.25Ce0.04Fe1.96O4 acquires the lowest coercivity of 567 Oe and the highest saturation magnetization of 52.23 emu/g. All the NMCCFx nanoferrites exhibit a microwave frequency range of 9.47–11.55 GHz, suggesting potential applications in longitudinal recording media and microwave absorbance. Moreover, the nanoferrite Ni0.5Mn0.25Co0.25Ce0.1Fe1.9O4 demonstrates the highest dielectric value of 1871, with an enhancing ratio of 754 %, excellent conductivity at 3.12 μ(Ω.m)−1 along with a remarkably enhanced percentage of 369 %. Additionally, it shows a loss factor of 2.17, with a notable improvement percentage of 26 % compared to the pure NMCCF0 sample at 50 Hz and room temperature. The elastic moduli (longitudinal, shear, Young, and bulk) of the Ni0.5Mn0.25Co0.25Ce0.1Fe1.9O4 nanoferrite increased from 1.21 to 2.77 GPa, 0.25–0.76 GPa, 0.68–1.99 GPa, and 0.87–1.75 GPa, respectively. This study introduces a novel approach to Ni–Mn–Co–Ce spinel nanoferrites, highlighting their magnetic, electrical, and mechanical characteristics, which hold promise for electronic and high-frequency device applications.

Effect of Annealing Temperature on the Characterizations of Cobalt Ferrite Nanoparticles Synthesized via Co-precipitation

This study investigates the effect of annealing temperature on the structural and magnetic properties of cobalt ferrite (CoFe2O4) nanoparticles synthesized via the co-precipitation method. The results indicate that the annealing temperature significantly enhances the crystal size and quality, yielding well-defined, impurity-free CoFe2O4 crystals. Magnetic measurements reveal that both saturation magnetization (Ms) and coercivity (Hc) are improved with annealing. The nanoparticles exhibit a soft-magnetic, single-domain state up to an annealing temperature of 1200°C. They reach a critical size of 39.7 nm and begin transitioning to a multi-domain state. These findings highlight the crucial role of annealing temperature in optimizing the properties of CoFe2O4 nanoparticles for potential applications in magnetic recording media, magnetic resonance imaging, magnetic fluid hyperthermia, biosensors, drug delivery, and cell separation.

Atomic level mechanism of disorder-order transformation kinetics at nanoscale in FePt based systems

L10 ordered FePt is one of the most promising materials for spintronic and recording media applications. In the present work, the mechanism of L10 phase transformation in FePt based films with varying initial structures is examined at the nanoscale to understand the ordering process using synchrotron based GIXRD, MOKE, VSM, and techniques with sub nanometer depth selectivity like XRR and SIMS. Precisely controlled compositions of the films are deposited using magnetron sputtering. Rapid thermal annealing is used for post-deposition processing. It is evaluated experimentally that for a shorter annealing time of 70 s at 400 °C, besides volume diffusion, short circuit diffusion paths along the intercrystallite region owing to the presence of nanostructured grains play a dominant role in alloying behavior. A study of the L10 ordering process reveals the crucial role of film structure in controlling the transformation kinetics, texturing of nanograins, and magnetic coercivity. Diffusion studies disclose that type B diffusion kinetics is activated for the annealing time during which L10 transformation occurs in the films.

Investigated the effects of surfactant concentration on cobalt ferrite nanoparticles synthesized in reverse micelles

The use of reverse micelles as nanoscale hydrophilic voids of microemulsions in the manufacture of ferrites has been recognized since the 1960s, but there has been very little attention on the structural and magnetic properties with respect to surfactant concentration. This paper investigates the influence of surfactant sodium dodecyl sulphate (SDS) concentrations on cobalt ferrite (CoFe2O4) nanoparticles prepared by reverse micelles at annealing temperatures 250°C and 500°C. Samples with varied cobalt to SDS ratios (Co: SDS = 1: 0.33, 1: 0.5, 1: 0.66) were subjected to XRD, TGA, TEM, FTIR and VSM Studies. All the samples exhibited single-phase spinel structures with crystalline diameters ranging from 10 to 18 nm. As the SDS concentration increased the crystallite size decreased. The TEM images showed the particle size in the range of 7.6 -17.7 nm. VSM investigations show the ferromagnetic behavior of the sample. The observed increase in coercivity with respect to annealing temperature for the same concentration reflects the single-domain nature of the nano particles. This underscores the crucial role of annealing conditions in customizing cobalt ferrite nanoparticles as a suitable application in longitudinal magnetic recording media.

Effect of Cr substitution on nickel spinel ferrite’s surface morphology, structure, antibacterial activity and magnetic properties

This study reports the sol–gel auto-combustion (SGACT) synthesis of Cr-substituted NiFe2O4 nanoferrites with a composition, of CrxNi(1−x)Fe2O4 (where x = 0.000, 0.025, 0.050, 0.100, 0.150, 0.200), and it examines the effects of chromium on spinel ferrite’s structure and properties. The doping of Cr at the nickel site is first reported in the present study. The computed crystallite size “t” from the XRD results was found in the range of 34.2–40.4 nm, whereas, FESEM plots show larger-sized grains due to the aggregation of a large number of crystallites for the produced nanoferrites. Maximum saturation magnetization of 42.44 emu/g was attained by the Cr0.050Ni0.950Fe2O4 (x = 0.050) specimen, whereas, the Cr0.200Ni0.800Fe2O4 (x = 0.200) specimen attains the maximum coercivity in the current study. All these excellent values of magnetic parameters make our SGACT-produced nanoferrites useful for magnetic recording media applications. In S. aureus, Cr0.200Ni0.800Fe2O4 nanoparticles showed the highest zone of inhibition (ZOI) whereas, Cr0.050Ni0.950Fe2O4 nanoparticles showed the least ZOI. On the other hand, in E. coli, Cr0.850Ni0.150Fe2O4, Cr0.200Ni0.800Fe2O4 and Cr0.050Ni0.950Fe2O4 nanoparticles showed good ZOI. This makes our developed nanoferrites beneficial for biological applications as antibacterial agents.

Synthesis and tailoring the structural and magnetic characteristics of Zn–Zr substituted Sr-hexaferrite targeting diverse applications

SrZnxZrxFe12-2xO19 (x varying within 0.1–0.4) samples were prepared successfully via solid state route. Their structural characteristics (along with microstructural and magnetic) have been discussed. Rietveld refinement established the phase purity for the samples x ≤ 0.3 (goodness-of-fit <1.15) whereas the presence of ZnFe2O4 and SrZrO3 impure phases was observed in x = 0.4 sample. The three-phase model resulted in decreasing χ2 values from 1.21 to 1.05 for x = 0.4 sample. The XRD findings also reveal an increasing cell volume from 690.675 Å3 (x = 0.1) to 693.096 Å3 (x = 0.3) and a decreasing porosity from 33% to 30% on increasing ˋx’. The average grain size increases from 0.83 μm to 1.04 μm according to FESEM micrographs with increasing ˋx’. The TEM measurements reveal the presence of rod like particles (in addition to random shaped particles) in x = 0.1–0.3 samples. M v/s H studies reveal, and increase in Ms from 90.26 emu/g (for x = 0.0) to 91.41 emu/g (for x = 0.1) and a decreasing trend afterwards to 87.90 emu/g (at x = 0.3). Hc value continuously decreases from 5032 Oe (for x = 0.0) to 1903 Oe (for x = 0.4). Low temperature M − H and M-T measurements coupled with room temperature M − H measurements reveal the absence of superparamagnetic behaviour. The magnetic data suggest that all the samples possess hard ferrite characteristics and could be useful for microwave absorbers, permanent magnets as well as high-density recording media applications.

A new hybrid non-aqueous approach for the development of Co doped Ni-Zn ferrite nanoparticles for practical applications: Cation distribution, magnetic and antibacterial studies

Ni-Zn spinel nanoferrite with a composition Ni0.6-xZn0.4CoxFe2O4 (x = 0.00, 0.033, 0.066, 0.132, 0.264 and 0.528) was produced at a low reaction temperature using a novel hybrid direct non-aqueous approach that eliminates the need for a complexing agent and a precursor that adjusts pH. The developed Ni0.567Zn0.4Co0.033Fe2O4 (x = 0.033), Ni0.534Zn0.4Co0.066Fe2O4 (x = 0.066) and Ni0.072Zn0.4Co0.528Fe2O4 (x = 0.528) nanoferrites attains the single-phase spinel cubic nano symmetry with a crystallite size of 54.91, 47.55, and 48.98 nm, respectively. Spherical shaped nanoparticles with aggregated behaviour were confirmed for the produced nanoferrites. XPS spectra of Ni0.072Zn0.4Co0.528Fe2O4 nanoferrite confirms the detection of major photoemission peaks of Zn2p, Ni2p, Co2p, Fe2p, O1s, and C1s. According to the BET research investigation, Ni0.072Zn0.4Co0.528Fe2O4 nanoferrite having specific surface area of 2.309 m2/g. The highest saturation magnetization and coercivity of 37.09 emu/g and 108.85 Oe was attained at higher doping content of cobalt (x = 0.528). With this nano crystalline nature and excellent magnetic factors, the developed nanoferrites are highly beneficial for the recording media applications to get the suitable signal to noise ratio and also, for multi-layer chip inductors (MLCIs). From the antibacterial investigation, it was observed that the produced Co doped Ni-Zn ferrites (x = 0.033, 0.264) shows high zone of inhibition (ZOI) for E. coli and Bacillus subtilis but the rest of the samples (x = 0.0, 0.066, 0.132, 0.528) shows no ZOI for both the bacterial strains. Therefore, the prepared Co doped Ni-Zn nanoferrites also works as superior antibacterial agent for biological application.

Atypical magnetism in Pt/MgO/FeCoB/Pt waveguide structure by exchanging the order of MgO and FeCoB layers

Interfaces in FeCoB/MgO/FeCoB magnetic tunnel junction play a vital role in controlling their magnetic and transport properties for various applications in spintronics and magnetic recording media. In this work, interface structures of a few nm thick FeCoB layers in FeCoB/MgO and MgO/FeCoB bilayers are comprehensively studied using x-ray standing waves (XSW) generated by depositing bilayers between Pt waveguide structures. High interface selectivity of nuclear resonance scattering (NRS) under the XSW technique allowed to measure structure and magnetism at the two interfaces, namely FeCoB-on-MgO and MgO-on-FeCoB, yielding an interesting result that electron density and hyperfine fields are not symmetric at both interfaces. The formation of a high-density FeCoB layer at the MgO/FeCoB (FeCoB-on-MgO) interface with an increased hyperfine field (∼34.65 T) is attributed to the increasing volume of FeCo at the interface due to boron diffusion from 57FeCoB to the MgO layer. Furthermore, it caused unusual angular-dependent magnetic properties in MgO/FeCoB bilayer, whereas FeCoB/MgO is magnetically isotropic. In contrast to the literature, where the unusual angular dependent in FeCoB based system is explained in terms of in-plane magnetic anisotropy, present findings attributed the same to the interlayer exchange coupling between bulk and interface layer within the FeCoB layer.

Rietveld refinement, magnetic and dielectric properties of Sr2+-Co2+-doped Zn2Y-type hexaferrites

In this experimental study, Sr2+-Co2+ was doped in Zn2Y-type hexaferrite to improve its magnetic and dielectric properties. Sol-gel auto combustion was used to synthesize Ba2-xSrxZn2-yCoyFe12O22 (x ​= ​0.0, 0.4, 0.8 and y ​= ​0.0, 0.5, 1.0), and the Retrieved refinement of XRD data confirmed the single-phase Y-type. Lattice constants a and c decreased from 5.867 to 5.854 Å and 43.566 to 43.470 Å, respectively. FTIR identified the absorption bands of hexaferrite at 405 cm-1 and 546 ​cm−1. An average grain size from FESEM decreased from 350 to 250 ​nm. Saturation magnetization and coercivity from M-H hysteresis loop for x ​= ​0.0, y ​= ​0.0, x ​= ​0.4, y ​= ​0.5, and x ​= ​0.8, y ​= ​1.0 are 40.04 emu/g, 42.77emu/g, 52.91emu/g, and 381.24 ​Oe, 261.44 ​Oe, 236.14 ​Oe respectively. The decrease in grain size, coercivity, and an increase in saturation magnetization make the prepared sample suitable for application in magnetic recording media. The material also deemed ideal for microwave devices due to its decreased dielectric constant values

Comparison of Structural, dielectric and magnetic investigation of Cr3+ substituted Mg-Cu, Mg-Zn, and Mg-Ni ferrites system

• Studied the effect of Cr 3+ substitution on the structural, dielectric, and magnetic properties of Mg 0.5 M 0.5 Fe 1.5 Cr 0.5 O 4 (M = Cu, Zn, and Ni) ferrite system prepared by sol–gel method. • The XRD patterns showed a single spinel phase. • The magnetic saturation (M s ), magnetic moment (M r ), and Coercivity (H c ) is found to be the highest for the Cr substituted Mg-Ni ferrite system. • All the synthesized samples showed ferrimagnetic behavior. • Thus, the magnetic and structural properties of (Mg 0.5 M 0.5 Fe 1.5 Cr 0.5 O 4 (M = Cu, Zn, and Ni) NPs can be favorable for their potential use in high-density recording media applications. Effect of Cr 3+ substitution on the structural, dielectric, and magnetic properties of Mg 0.5 M 0.5 Fe 1.5 Cr 0.5 O 4 (M = Cu, Zn, and Ni) ferrite system prepared by sol–gel method. All ferrites prepared samples’ powder; X-ray diffraction patterns confirmed the formation of single-phase cubic spinel structures with Fd -3 m space group. It possesses a monophasic cubic-spinel lattice structure with an average crystallite size ranging from 25 to 44 nm. The lattice constant determined by XRD analysis falls between 8.497 Å and 8.392 Å. Furthermore, the crystallite size determined by XRD data is well matched with the particle size determined by scanning electron microscopy images. Using an LCR Meter, the dielectric parameters of the samples, such as dielectric constant ( ε ’) and dielectric loss tangent (tan δ ), were studied as a function of frequency in the range of 100 Hz to 5 MHz at room temperature. The dielectric constant and loss tangent among the samples show a normal dielectric behavior with a frequency which reveals that the dispersion is a result of the Maxwell-Wagner type interfacial polarization and hopping of electrons between the Fe 2+ and Fe 3+ ions. The hysteresis curve exhibits the particles are soft ferrimagnetic with maximum saturation magnetization, Ms = 38.55 emu/g due to Cr substituted Mg-Ni ferrite. The squareness ratios were discovered to be less than 0.5, indicating that our particles have a single-domain ferrimagnetic isotropic nature. Thus, the magnetic and structural properties of (Mg 0.5 M 0.5 Fe 1.5 Cr 0.5 O 4 (M = Cu, Zn, and Ni) NPs can be favorable for their potential use in high-density recording media applications.

Tailoring the structural and magnetic traits of copper modified BaFe12O19 nanostructured hexaferrites for recording media application

Barium nanohexaferrites, with a chemical composition of Ba1-0.5xCu0.5xFe12O19 (x = 0.0, 0.1, 0.2, 0.3) have been successfully produced using the sol–gel auto-combustion approach for tuning its structural, morphological, optical and magnetic properties. The current work has been carried out to control the coercivity of synthesized specimens, with the modification of copper ions at the barium sites of BaFe12O19 hexaferrites. The XRD patterns of synthesized specimens’ shows the formational of hexagonal-like crystal structure with P63/mmc space geometry. In the XRD diffraction patterns, the characteristic peaks (110), (008), (107), (114), (108), (203), (205), (206), (1011), (300), (217), (2011), (220), (2014)along with some impurity phases of hematite (α-Fe2O3) were observed. The crystallite size “D” was estimated from the observed XRD patterns using the Debye-Scherrer formula in the range of 41.94–83.91 nm respectively. The FESEM studies of the BM2 and BM3 specimens reveal the presence of agglomerated grains with a hexagonal shape and an average size of ∼ 277 and ∼ 469 nm respectively. The energy dispersive X-ray spectra of synthesized nanohexaferrites shows only peaks of copper, iron, barium, and oxygen which clearly confirms the higher purity of pure and doped barium hexagonal nanoferrites. The transmission electron micrograph of BM1 nanohexaferrite illustrates the production of the nanoparticles that are agglomeratedand spherical, and have an average particle size of 53.32 nm. The Raman spectrum of undoped and copper doped BaFe12O19 hexagonal nanoferrites shows the formation of seven Raman active vibrational modes in the frequency range of 200–800 cm−1. At room temperature (300 K), the magnetic traits of the produced barium hexagonal nanoferrites were measured, and using these measurements, a variety of magnetic parameters (Ms, Hc, Mr, and Ha) were reported. The value of saturation magnetization (Ms) increases from 37.75 emu/g to 59.97 emu/g with increased low copper content up to x = 0.1. In contrast, with the increasing copper content up to x = 0.3, the value of Ms shows a decline to 28.31 emu/g. In this work, admirable values of Ms (28.31–59.97 emu/g) and Hc (684–2563 Oe) were obtained, making these nanohexaferrites as beneficial candidates for the recording media and EMI shielding applications.

Dysprosium doped Cu0.8Cd0.2DyxFe2-xO4 nano ferrites: A combined impact of Dy3+ on enhanced physical, optical, magnetic, and DC-electrical properties

The current study focuses on the influence of rare-earth Dy3+ ion substitution on the structural, optical, electrical, and magnetic properties of Cu0.8Cd0.2Fe2O4 nano-ferrites. A series of Dy3+ doped Cu–Cd nano-ferrites with the chemical composition of Cu0.8Cd0.2DyxFe2-xO4 (x = 0.00, 0.025, 0.05, 0.075, and 0.10) were fabricated by CSGAC (citrate sol-gel auto combustion) technique using the corresponding elements in nitrate state and grounded powders were calcined at 650 °C for 4 h. These ferrite nanoparticles (NPs) structural, optical, magnetic, and electrical properties were investigated using P-XRD, FE-SEM, HR-TEM, FTIR, UV–Vis, ESR, VSM, and I–V measurements. The purity of the crystal structure, phase formation, and the various structural parameters of Cu–Cd-Dy nanoparticles have been analyzed from P-XRD data. The evaluated crystalline size ranges between 13.82 and 18.32 nm, and the lattice constant is between 8.349 and 8.385 Å. We observed the particles-size of 40–60 nm from HR-TEM and the grain size of 48–80 nm from FE-SEM images. The observed FTIR spectra demonstrated the spinel structure in the presence of the stretching bonds of metal-oxides and functional groups. The semiconducting character of the produced NPs is confirmed by the optical bandgap, which is in the range of 1.62 eV–1.73 eV. The g-value obtained from the electron spin resonance (ESR) spectroscopy is in the range of 2.613-2.333. The coercivity (Hc) reduced from 557.29-183.89 Oe at 300 K and 749.85-410.72 Oe at 15 K, respectively, with Dy3+ concentration. The maximum saturation magnetization obtained at 300 K temperature for x = 0.025 is 32.53 emu/g, whereas at 15 K for x = 0.1 is 38.85 emu/g. The results of the present examined samples with improved Hc, Ms, and Mr values at low temperature (15 K) than room temperature (300 K) revealed that Dy3+ doped Cu0.8Cd0.2Fe2O4 nanoparticles are helpful for high-density recording media application. By increasing the Dy3+ addition, the resistivity values were observed to increase from 9.107×106 to 1.166×108 Ω-cm.

Compositional Dependence of Magnetocrystalline Anisotropy, Magnetic Moments, and Energetic and Electronic Properties on Fe-Pt Alloys.

This work reported the first-principles calculations for the compositional dependence of the energetic, electronic, and magnetic properties of the bimetallic Fe-Pt alloys at ambient conditions. These hybrid alloys have gained substantial attention for their potential industrial applications, due to their outstanding magnetic and structural properties. They possess high magnetocrystalline anisotropy, density, and coercivity. Four Fe-Pt alloys, distinguished by compositions and space groups, were considered in this study, namely P4/mmm-FePt, I4/mmm-Fe3Pt, Pm-3m-Fe3Pt, and Pm-3m-FePt3. The calculated heats of formation energies were negative for all Fe-Pt alloys, demonstrating their stability and experimentally higher formation probability. The P4/mmm-FePt alloy had the lowest magnetic moment, leading to durable magnetic hardness, which made this alloy the most suitable for permanent efficient magnets, and magnetic recording media applications. Moreover, it possessed a relatively large magnetocrystalline anisotropy energy value of 2.966 meV between the in-plane [100] and easy axis [001], suggesting an inside the plane isotropy.

Correlation between Composition and Magnetic Properties of SrFe&lt;sub&gt;12&lt;/sub&gt;O&lt;sub&gt;19&lt;/sub&gt;/Co Nanocomposite Synthesized by the High Energy Ball-Milling Process

Nanocomposites (NCs) (100-x) SrFe12O19/x Co (x = 10, 20, and 30 wt. %) were produced using the high energy ball-milling (HEBM) process. The effects of hard/semi-hard ratio and annealing temperature (800, 900, and 1000 °C) on the exchange-spring in magnetic NCs were discussed. X-ray diffraction examination showed the coexistence of M-type hexaferrite SrFe12O19 (SFO) as the hard phase and CoFe2O4 spinel ferrite (CFO) as the semi-hard phase. Using a scanning electron microscope (SEM), the morphology and elemental analysis of the NCs were analyzed. The magnetic performances were investigated via a vibrating sample magnetometer at room temperature. With increasing the CFO content and annealing temperature, the hysteresis loop became narrower and possessed semi-hard magnetic properties. The 10 wt. % Co NCs annealed at 800 °C had the highest coercivity of Hc = 4.2 kOe. These results are correlated with switching field distribution plots that have indicated the efficient exchange-spring between SFO and CFO phases NCs annealed at 800 °C. The studied samples can be a promising candidate in permanent magnets and magnetic recording media applications.

Microstructural segregation in high anisotropy [Co/Pt]n superlattice films

We show microstructural segregation in oxide containing [Co/Pt]n superlattice films with strong perpendicular magnetic anisotropy for application in advanced high-density magnetic recording media. By adding optimized mixtures of oxides into the Co and Pt layers of the superlattice, films with columnar grains, ~8nm grain pitch (GP), σGP/<GP>~17% and controlled intergranular exchange are demonstrated. The magnetic, microstructural and crystal properties of these films were investigated as a function of Pt thickness and oxide content.

Néel Skyrmionic States and Chiral Stripes in the Magnetic Bilayer with Transverse Easy Axis

Chiral spin structures, such as skyrmions, are topologically nontrivial magnetization configurations, which have potential applications in magnetic recording media. In particular, an antiferromagnetically coupled system that hosts skyrmions is of great interest because of high-speed skyrmion motion and reduced skyrmion Hall effect. Here, we consider TbCo/GdFe-based amorphous ferrimagnetic system showing chiral stripe domains and Neel-type skyrmions. It is observed that skyrmionic configurations are stabilized with the help of dipolar interactions that exist in the system. Optimized thicknesses of TbCo (30 nm) and GdFe (6 nm) show isolated skyrmions in both the layers with average skyrmion diameter of 40 ± 5 nm. We have also investigated a phase diagram in a wide range of layer thickness, which represents the presence of the mixture of either vortex, chiral stripes, or/and Neel-type skyrmions. To understand the underlying phenomena which help chiral ferrimagnetism in this kind of amorphous system, we perform layer-resolved micromagnetic modeling. We found variety of chiral textures in a wide thickness range of ferrimagnetic bilayer systems, which may be useful for fundamental understanding of formation of skyrmion and their application in spintronic devices.

Scrutiny and correlations of structural, magnetic, and dielectric properties of M-type strontium hexaferrite (SrFe12O19) for permanent magnet applications

Strontium hexaferrite has achieved immense attention in industries, manufacturing crucial components for devices, technological applications, and machine making due to its high coercivity value. The efficient technique of sol–gel auto-combustion was espoused for the synthesis, and the morphological studies affirmed the hexagonal shape of the particles. The magnetic analysis revealed the sample being a potential substance for perpendicular recording media applications. The dielectric studies disclosed relaxations and polarization effects existing in the material. The linkage of structural, magnetic, and dielectric properties and their inter-influences are the remarkable consequences of the research work.

Novel ferrimagnetic nanomaterial Sr(1−x)LaxGdySmzFe(12−(z+y))O19 for recording media applications: experimental and theoretical investigations

Developed novel ferrimagnetic nanomaterial Sr(1−x)LaxGdySmzFe(12−(z+y))O19 has a significant function in industry, which could be beneficial for recording media applications.

High temperature magnetic behavior of Ba0.5Sr0.5Fe12O19 nanoceramics for high density recording media applications

M − type barium strontium hexagonal ferrite (Ba0.5Sr0.5Fe12O19) is prepared using citrate precursor based sol–gel method. The X- ray diffraction pattern reveals pure phase synthesis of samples with hexagonal crystal system indexed to P63/mmc space group. The average grain size is found to be above 52 nm. Particle size and lattice strains monotonically increased with increase in annealing temperature. The Williamson-Hall plot is drawn and analyzed to find out crystallite size and induced lattice strains in samples. The lattice parameters are determined with Fullprof Rietveld refinement of XRD pattern which shows noticeable increments. SEM morphological analysis is in consistent with XRD patterns. Vibrating sample magnetometer is used for finding parameters like magnetization, coercivity and anisotropy constants, which is maximum for Ba0.5Sr0.5Fe12O19 annealed at 1000℃. All the prepared nanomaterials show appreciable Magnetization 43.23 – 57.48 emu/g, Retentivity 21.33 – 29.26 emu/g at 300 Kelvin. Coercivity values showed drastic increment from 1196 to 3203 Oersted. Curie temperature gets shifted to 449℃ from 442℃ for samples annealed at 1100℃. Therefore, influence of lattice strain on structural and magnetic properties Ba0.5Sr0.5Fe12O19 ceramics at room temperature, and at elevated temperatures is explored in this article.

Synthesis and tuning the electro-magnetic properties of Co-Cr substituted Sr-hexaferrite towards diverse usages

Strontium hexaferrite is one of the powerful commercial magnets due to its unique characteristic combination of physical, magnetic, and dielectric properties. According to the necessity, their magnetism may be altered as either hard or soft by substitutional effectiveness of the transition elements and optimization of processing parameters. Here, SrFe12-(x+y)CoxCryO19 (x,y = 0,0; 0,1; 0.25,0.75; 0.50,0.50; 0.75,0.25; 1,0) nano ferrites have been successfully synthesized by the sol–gel self-propagation process and the impacts of Co-Cr on the microstructure, densification, magnetic, dielectric, and electrical properties have been analyzed. The XRD data discloses the crystalline ferrite phase with a hexagonal structure (P63/mmc). It is found that the magnetic properties can be tuned up effectively by the substitutions. The samples show a range (0.02–0.48) of the squareness (Mr/Ms) ratio suitable for diverse industrial applications. SrFe11CrO19 composition reveals magnetic improvement in Ms (60 emu/g) and Hc (6.3 kOe) along with decent energy product, i.e., 27.17 MGOe, optimized to approach for a permanent magnet. SrFe11Co0.75Cr0.25O19 & SrFe11CoO19 compositions show a great dilution in hard magnetism having Ms of 71 emu/g along with Hc of 36.21 Oe and 3.23 Oe, respectively. It has opened up the opportunity of possible emersion of the hard magnet in the magnetic recording media application. The proposed work is expected to offer a good notion to modify strontium hexaferrite in order to expand its application areas.