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Due to the excessive use of electronic devices in this modern technological age, the issue of electromagnetic interference (EMI) has become a concern. To address this, Ca–Pb W-type hexaferrites were synthesized with the composition Ca0.5Pb0.5Co2−xMgxLayFe16−yO27, where x and y vary between 0.0 and 1.0, with a step of 0.2 and 0.02, respectively. The samples were prepared using the sol–gel auto-combustion method. The results of the X-ray diffraction analysis showed the formation of a single-phase hexaferrite structure by examining its structural parameters. This was confirmed as all the peaks observed matched the reference pattern stored in the ICDD database with the number 01-082-0041. Scherrer's formula was used to calculate crystallites size which ranged from 41 to 76 nm. The formation of hexaferrites was confirmed using Fourier transform infrared spectroscopy, which detected two absorption bands below 1000 cm−1. Energy-dispersive X-ray spectroscopy revealed that all of the sample's elements were present. Scanning electron microscopy micrographs revealed the shape and distribution of the particles. Frequency-dependent dielectric parameters were evaluated for all concentrations in a range between 1.0 MHz and 3 GHz. At frequencies that are relatively low, the materials exhibit high values of both dielectric constant and dielectric loss. Furthermore, the AC conductivity of these materials is significantly low at lower frequencies. However, as the frequency increases, the conductivity of the materials gradually begins to increase, and this rise is marked by the emergence of resonance peaks. These characteristics make the material well-suited for use as electromagnetic interference (EMI) filters and chokes. [ABSTRACT FROM AUTHOR]

The rare earth (Yb3+) substituted W-type hexagonal ferrites with composition CaPb 2-x Yb x Fe 16 O 27 (x = 0.0, 0.5, 1.0, 1.5, 2.0) were synthesized by a facile and cost-effective sol-gel auto combustion method with post heat treatment. The synthesized hexagonal ferrites were characterized by a variety of analytical techniques, and an impedance analyzer was used to investigate the effects of Ytterbium on structural, magnetic, spectral and dielectric properties. The relationship between their impedance, structure and dielectric properties was investigated. The X-ray diffraction patterns verify the presence of single-phase W-type hexagonal ferrites. Physical properties such as D bulk (bulk density), D xrd (X-ray density), and P (porosity) of the CaPb 2-x Yb x Fe 16 O 27 W-type hexagonal ferrites were calculated. The bulk density of all the samples was decreased, and X-ray intensity was increased with the Ytterbium replacement in the W-type hexaferrite. By adding Yb3+ ions, the lattice parameters, cell volume and X-ray density were reduced due to the substitution of ytterbium with smaller ionic radii compared to the lead ion with large ionic radii. The AC-conductivity was increased from (1.523 × 10−5 to 6.699 × 10−5) Ωcm−1. The dielectric constant and tangent loss was found to decrease substantially. The magnetic properties were found to enhance by the substitution of Yb3+. The low coercivity value of Yb3+ substituted W-type hexagonal ferrites are suitable for magnetic recording media operated at a high-frequency regime. The enhancement of electrical, dielectric and magnetic characteristics suggests these materials as promising for multi-layer chip inductors (MLCIs) circuit applications. [ABSTRACT FROM AUTHOR]

M -type hexagonal ferrites with compositions Ca 1 − x CrxFe 1 2 O 1 9 at (x = 0. 1 , 0.2, 0.3, 0.4, 0.5) were successfully prepared by sol–gel auto combustion method and then immersed with polyvinyl alcohol (PVA) by ultrasound-assisted in situ emulsion technique. The results indicate that the synthesized nanoparticles were diffused homogeneously in PVA retaining the size and shape of the particle. The single-phase M -type hexagonal structure was revealed by X-ray diffraction (XRD) with extra 101 peak of PVA at 2 θ = 1 8 ∘ . The suitable signal-to-noise ratio in the high density recording media can be achieved due to the small particle size of the prepared composites as compared to pure hexaferrites. The interaction between PVA and nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) images revealed the homogeneous distribution of grains, the crystallite size was measured from SEM (25–38 nm), and it is also in agreement as calculated from the Scherer formula. Dielectric properties were also explored in the range of 1 MHz–3 GHz frequencies. Dielectric constant and dielectric loss were found to decrease with increasing frequency and decrease with the addition of ferrite ratio in the polymer matrix. This impact is because of the grain boundary at low frequency regime. The occurrence of resonance at high frequency regime recommends the investigated samples for multilayer chip inductor. The formation of PVA-Ferrite Nanocomposites was confirmed by the FTIR in the range of 3500–400 cm–1 wavenumbers. The FTIR spectra of ferrite-polymer composites (PF3,PF5) were shown. The absorption bands in the range of 500–600 cm–1 wavenumbers are due to stretching vibrations at tetrahedral sites and absorption bands in the 400–500 cm–1 wavenumbers demonstrate the octahedral site formation in the M-type hexagonal ferrites structure. The absorption band at 1600 cm–1 is due to the stretching bands of hydroxyl group -O-H. Slight shifts in the bands were recorded due to the addition of polymer. Due to the interaction of ferrites-polymer, force constant and electron density were found to be decreased. [ABSTRACT FROM AUTHOR]

The x-type hexaferrites have been getting considerable attention owing to their promising application in electronic fields. Though, the growth of nanosized crystal X-type hexagonal ferrites is still a big challenge. Herein, the synthesis of nanosized X-type hexagonal ferrites Ca 2 Co 2−x Zn x Fe 28 O 46 (X = 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0) with high quality is reported using the auto-combustion sol-gel method. The objective of the study was to improve the structural and dielectric properties of X-type hexagonal ferrite which was achieved through variation of concentration of cobalt and zinc. Structural, morphological, and dielectric properties were investigated. X-ray diffraction (XRD) patterns confirmed the single-phase x-type hexagonal structure. The crystal size of all samples was in the range of 22.7–23.8 nm. Other parameters such as d -spacing, lattice parameters, unit cell volume, dislocation density, atomic packing fraction, degree of crystal lattice distortion, number of the unit cells, and volume of particles were also calculated. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of metal oxide bonds with two absorption bands at 574 cm−1 and 424 cm−1. The morphology of the prepared Ca 2 Co 2−x Zn x Fe 28 O 46 with the variation of Co and Zn was examined by scanning electron microscopy. Increasing crystallinity and agglomeration were observed with the upsurge in Zn and Co. The dielectric properties of Ca 2 Co 2−x Zn x Fe 28 O 46 with the variation of Zn and Co revealed that these materials might be considered good candidates for modern devices. [Display omitted] • Nanosized X-type hexagonal ferrites was synthesized by auto-combustion sol-gel. • Crystal size of all samples was in the range of 22.7–23.8 nm. • Dielectric properties revealed that materials are good candidate for devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • M type hexaferrites with composition Pb 1-x Cr x Fe 12 O 19 x = (0.0,0.1,0.2,0.3,0.4,0.5) were synthesized by the sol-gel auto combustion technique. • Peaks of the XRD pattern match well with the standard pattern of P63/mmc group with JCPDS card No (43-0002). • Crystallite size lies in the range of 63–53 nm. Lattice parameters, crystallite size and cell volume was found to decrease with the substitution of Cr3+ content. • Dielectric constant and ac conductivity (σ ac) increases gradually with the increase in Chromium doping. Mofreover, Pb 1-x Cr x Fe 12 O 19 with x = 0.2 have exceptional dielectric properties with significant Q-value (4900). • These samples may suitable for high frequency applications such as phase shifter, modulators and also in longitudinal recording media. Chromium substituted M-type hexagonal ferrites with nominal composition Pb 1-x Cr x Fe 12 O 19 where x= (0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared via sol gel route. Structure of the single phase lead hexaferrite was estimated from X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) confirmed the formation of hexagonal platelets with an average grain size in the range of 53–63 nm. Crystallite size, lattice parameters and cell volume was found to decrease with the increase of Chromium concentration. Magneto crystalline anisotropy and saturation magnetization has been explored through the law of approach to the saturation magnetization. Saturation magnetization first increased and then found to be maximum (64 emu/g) at 30% of Cr3+ doped lead hexaferrite and minimum coercivity (6.54 KOe) was perceived for this composition. Dielectric constant, dielectric loss, tangent loss, real and imaginary part of electric modulus, ac conductivity and Q-values of the prepared samples were also explained. With the increase of dopant (Cr3+) concentration, dielectric constant was increased gradually. These characteristics are suitable for various applications such as phase shifter, modulators, stealth technologies and also in Multilayer chip inductor. [ABSTRACT FROM AUTHOR]