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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 structural, magnetic, and dielectric properties of Yb ions substituted Ca-hexaferrites (Ca-HFs) synthesized using the citrate sol–gel method were studied. XRD and SEM, techniques were used to evaluate the size and shape of the samples. X-ray powder diffraction (XRD) patterns of prepared samples revealed the production of a single M-type single phase hexagonal ferrite with space group 167: R-3c, hexagonal of P63/mmc for structural characterization. Using a scanning electron microscope, the surface morphology of the particle was investigated, and the particle size was determined (SEM). FTIR spectra confirmed the iron–oxygen bands of X-type hexagonal ferrites at tetrahedral and octahedral sites. The high influence of Yb+3 substitutions on the FTIR spectra further confirmed that the dopants play a significant role in these ferrites. The electrical and dielectric properties of Yb substituted Ca-HFs were investigated using the complex impedance spectroscopy technique at various temperatures, frequencies, and substitution ratios. Yb substitution was discovered to have a significant impact on dielectric loss, dielectric constant, Ac conductivity, and dissipation factor. It was fascinating to see how Ytterbium replacement resulted in a significant improvement in magnetic characteristics. With a given substitution ratio, activation energy levels can be altered to a certain level. The Verway Hopping Model, Maxwell Wagner Model, and Koop's theory were used to describe the conduction and polarization mechanisms. The trend was also influenced by the substitution of Yb. Eddy current losses, devices like Multi-Layer Chip Inductors (MLCI), and other microwave applications can benefit from the achieved ranges of both features. [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]

Sol-gel auto combustion was used to create a sequence of soft ferrites, NixMg1-xFe1.9Sm0.1O4(x = 0.0, 0.2, 0.4 & 0.6). The XRD, FTIR, UV-vis, & four probe I-V techniques, respectively, were used to evaluate the structural, optical, and electrical properties. The cubic crystal structure was confirmed by the XRD pattern. The range of 25.71 - 33.67 nm was found to be the average crystallite size. FTIR spectra provided evidence of the tetrahedral band's existence. With the enhancement of Ni2+ concentration, Eg was determined from 2.28-3.21 eV. It was confirmed by the ranges of DC electrical resistivity that materials might be used in transformers to lessen eddy current losses. [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]

A significant structural modification and enhancement of the electrical and magnetic properties with dilute substitution of Zr (≤1mol.%) in the Bi0.8La0.2Fe1-xZrxO3 system has been reported. A mixture of rhombohedral and orthorhombic phases was detected in these conventionally sintered ceramics. Transition from a leaky state to an insulating state was observed upon Zr substitution. This is the first time that a drop in the electrical conductivity as large as 6 orders of magnitude for doping as small as 0.25mol. % in bismuth ferrite systems has been reported. An investigation on the nature of this abrupt transition revealed the dominant role of defects. A proper consideration of possible defect reactions taking place during and after sintering satisfactorily accounts for the observed modulation in the electrical properties. Both AC and DC measurements indicate that, before Zr substitution, ptype hopping conduction prevails with an activation energy as low as ~0.57 eV, whereas the Zr substitution makes oxide ion migration the central mechanism for conduction with the activation energy of ~0.96-1.08 eV. In contrast to that, the magnetic properties of the compounds experience a more subtle effect; a gradual modification of saturation magnetization and coercivity with Zr substitution is observed. Curve fitting of the magnetic hysteresis loops not only allowed extraction of three separate contributions from the magnetic response but also helped to explain the effects of Zr on the magnetic properties. Modifications of structural characteristics and magnetic anisotropy of the samples are believed to be the primary driving force behind the improvement in the magnetic properties. [ABSTRACT FROM AUTHOR]

• The samples Ca 0.5 Ba 0.5-x Cu x Fe 2 O 4 (x = 0.00, 0.125, 0.250, 0.350, 0.500) spinel ferrites prepared by sol–gel auto combustion method results in enhanced structural, dielectric and magnetic properties. • XRD patterns of samples indicate that the peaks match well with the standard patterns of the spinel ferrites. • Crystallite size lies in the range of 37.43–50.07 nm. • At room temperature the conductivity of ferrites is due to impurity, as at higher temperature conductivity is occurring through polaron hopping. • Dielectric constant according to Maxwell–Wagner model the dielectric substance contains with heterogeneous structure thought that good conducting grains separated by highly resistant thin grain boundaries. • Dielectric losses very essential part of the sum core loss in magnetic materials, According to Hudson theory. Copper-substituted spinel ferrites with nominal composition Ca 0.5 Ba 0.5-x Cu x Fe 2 O 4 (x = 0.00, 0.125, 0.250, 0.350, 0.500) were successfully prepared by the sol–gel auto combustion route. The fabricated Nano-ferrites underwent a five-hour annealing process at 800 °C in a furnace. By the X-ray diffraction (XRD) analysis and dielectric measurements, the structural and electrical behavior of Ca 0.5 Ba 0.5-x Cu x Fe 2 O 4 nanoparticles were examined. Formations of a single-phase cubic structure of all prepared samples were estimated by the X-ray diffraction analysis. Crystallite size ranges from 37.43 to 50.07 nm. With the addition of Cu2+ cation, the lattice parameter, dielectric characteristics, and magnetic parameters were enhanced. It was observed that dielectric properties were improved significantly with the doping of copper. The dielectric constant and dielectric loss were found to decrease at high frequencies. On the other hand, an increase in AC conductivity was observed with increasing frequency by Maxwell Wagner and Koop's models. The VSM study confirms the improved magnetic properties of the sample. Remanent magnetization, saturation magnetization, and coercivity were improved significantly with the doping of copper cation. Based on these improved dielectric and magnetic characteristics, the prepared materials are strongly recommended for different electronic components and energy storage devices. [ABSTRACT FROM AUTHOR]

The main theme of this work is to synthesize and investigate different properties of Pr3+‐Cu2+ substituted X‐type hexaferrite Sr2‐xPrxCo2Fe28‐yCuyO46 with concentration (x = 0, 0.02, 0.06, 0.1 and y = 0, 0.1, 0.3, 0.5) by adopting the sol–gel method. The XRD patterns show the single phase for all the samples. The Pr3+‐Cu2+ substitution in pure X‐type hexaferrites changes the structural parameters. The increment in dielectric properties with Pr3+‐Cu2+ substitution is observed and the patterns show anomalous dielectric behavior. The FTIR analysis also confirms the single phase for the prepared materials. The magnetic properties of the material are enhanced with additives. The difference in saturation magnetization, coercivity, and remanence is observed on the basis of allocated cations onto the different lattice sites. The linear increase in saturation magnetization, remanence, and coercivity make them useful as permanent magnets. The thermal analysis is carried out to know the sintering temperature at which the single X‐type phase can be attained. The material exhibits the minimum value of reflection loss (microwave absorption) at higher frequencies that make this material useful to act as microwave absorbing material (MAM) for super high frequency (SHF) devices. [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]

Abstract: Effect of Pr–Ni substitution on structural and magnetic properties of Ca0.5Ba0.5−x Pr x Ni y Fe12−y O19 (x=0.00–0.10 and y=0.00–1.00) prepared by the sol–gel auto combustion method were investigated. The XRD analysis confirmed the single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as Pr–Ni content increases, which is attributed to the ionic size of the implicated cations. The Pr–Ni seems to be completely soluble in the lattice. Transmission electron microscopy reveals that the grain size decreases with increase of Pr–Ni substitution. The coercivity and remanent magnetization ranges from 1511 to 1925 (Oe) and 21.4 to 26.5 (emu/g), respectively. The coercivity values of all the samples fall in the range of M-type hexa-ferrites. [Copyright &y& Elsevier]

Highlights: [•] Tb–Zn substituted Ca0.5Ba0.5Fe12O19 samples exhibit single magnetoplumbite phase. [•] Lattice parameters a and c have increasing values. [•] Coercivity can be tuned at lower substitution level [•] Crystallites size was found in the range 18–25nm by TEM and by Scherrer formula. [•] These hexa-ferrites are suitable for microwave devices and magnetic recording media. [Copyright &y& Elsevier]

Cadmium ion doped in Zn–Mn soft ferrites was synthesized by co-precipitation method. Cadmium content can improve the micro-structure, magnetic, electrical, optical, and vibrational properties. Single-phase cubic structure of all samples of cadmium-doped Zn–Mn soft ferrites was confirmed by using X-ray diffraction technique. Crystalline size of the material was investigated by using XRD pattern. FTIR analysis observed that the metal oxide group (M–O) exists in the presented samples. The DC resistivity decreased as the concentration of cadmium and temperature increases, and also, with the increase in cadmium contents, optical band gap decreased and Raman shift increased. [ABSTRACT FROM AUTHOR]

In the present investigation, the divalent basic element "Sr2+" was replaced with another divalent element "Mg2+" to understand the influential effect of Mg2+ on structural, electrical, dielectric and FTIR properties of Sr2+ based R-type hexagonal ferrites Sr 1-x Mg x Fe 4 Sn 2 O 11 with composition (x = 0.0, 0.1, 0.2, 0.3). The material was synthesized by sol-gel auto combustion method and sintered at 800 °C temperature for development of the required phase. The XRD and FTIR analysis revealed the formation of single-phase R-type hexagonal ferrites. It was observed that the values of lattice parameters a (Å), c (Å), crystallite size (nm), X-ray density (g/cm 3 ) and unit cell volume V (Å) 3 changed with Mg2+ substitution. The Scherer formula was used to find the crystallite size which varied in the range from 11 to 13 nm for all synthesized samples. The FTIR spectra also indicated the presence of negligible amount of moisture and Nitrogen in sample, absorbed from the atmosphere. The dielectric constant results showed the higher values for Mg2+ substituted samples than the pure sample. Furthermore, Debye function was used for the fitting of the dielectric constant results which indicated the participation of more than one ion in the increment of dielectric constant. The AC conductivity increased with the increase of frequency, consequently the experimental result was compared with theoretical results by Jonscher's power law which elicited the conduction mechanism. The P-E (polarization vs. electric field) loops substantiated the decrease in saturation and remnant polarization with Mg+2 content. The electrical resistivity of synthesized sample unveiled the resistive nature of sample significantly. It is suggested that the present R-type ferrites are useful in microwave absorption devices and in transformer to reduce the eddy current losses. [ABSTRACT FROM AUTHOR]

Nanocrystalline Mn-Zn ferrite nanopowders (Mn0.5Zn0.5Fe2O4) were synthesized by co-precipitation technique and post-fabrication annealing has been performed at different temperature ranges from 400 to 700 °C for 2 h. The effect of annealing on morphology, crystalline phase formation, cation distribution, lattice constant, particle size, magnetic properties, and optical properties was studied by scanning electron microscopy (SEM), x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and UV-visible spectroscopy (UV-Vis) respectively. The crystallite size increased from 14 to 24 nm with the annealing temperature owing to the grain growth process or more technically we say Ostwald ripening mechanism. The decomposition of ferrites at low-temperature results in the formation of hematite Fe2O3 eventually reduced the magnetic properties of ferrites. The hematite, impurity phase, started to dissolve or converted into the ferrite phase after 600 °C. The sample annealed at 700 °C shows a better crystalline structure, phase formation, and larger magnetization compared to the other ferrite samples. The improved magnetic behavior after heat treatment is due to the better alignment of domains at the cost of the grain growth process. The UV-Vis spectroscopy result revealed the maximum absorbance at 380 nm. [ABSTRACT FROM AUTHOR]

A series of W-type Ba-based Co-W ferrites with composition BaCoxCd2-xFe16O27 (x - 0.0, 0.1, 0.2, 0.3, 0.4 & 0.5) were fabricated by co-precipitation process at sintering 1100 °C for 8 h. In order to investigate structural, optical, electrical and magnetic properties XRD, FTIR, IV and VSM tools were employed to confirm the formation of ferrites phase. Crystallite size was observed in the range of 71.79 - 27.88 nm with the increase of cobalt contents to confirm the formation of W-type phase. FTIR investigated the existence of metal oxide (M - O). Electrical resistivity increased in the range of 0.2315 x 107 - 0.5329 x 107 ohm.cm. Saturation magnetization (Ms) of the synthesized sample were observed in the range (37.36 emu/g to 87.42 emu/g) and remanance (Mr) found (2.21 emu/g to 27.81 emu/g) while coercivity (Hc) observed in the range (42.58 Oe to 346.55 Oe). Explored results revealed that such type of behavior by material is suitable for application of magnetic recording media. [ABSTRACT FROM AUTHOR]

A series W-type BaMe2Fe16O27 ferrites withcomposition BaZnxCo1-xFe16O27(x - 0.0, 0.1, 0.2, 0.3, 0.4 &0.5) were manufactured by co-precipitation method sintering at 1100°C for 8 h. XRD, FTIR, SEM, UV-vis and I-V techniques were applied to investigate structural, optical, morphological and electrical properties respectively. Crystallite size was observed in the range of (37.58 nm-54.75 nm) revealed by XRD and was confirmed by SEM analysis. IR exposed the existence of metal oxides (M-O). Optical band gap was in (3.0 eV-5.2 eV) range which proved the trend of DC resistivity in increasing trend. Activation energy discovered the conversion of ferrimagnetism to paramagnetism characteristics confirming the W-type materials are highly suitable for novel application. [ABSTRACT FROM AUTHOR]

Holmium (Ho 3+ ) substituted W-type hexagonal ferrites (BaCo 2 Fe 16 O 27 ) were prepared by sol gel auto-combustion technique. The precursors were prepared by Ba 2+ , Fe 3+ nitrates solutions with citric acid as chelating agent. The prepared powder was sintered at 950 °C for 8 h to produce a single phase of W-type hexa ferrite with corresponding crystallite size ranging from 34 nm to 44 nm. The thermal decomposition of nitrate-citrate gel of as-prepared powder was investigated by TGA and DTA. The FTIR spectral study reveals the presence of two absorption bands which are characteristics of hexaferrites. DC electrical resistivity increases from 3.01×10 9 to 5.69×10 10 (ohm-cm). The real and imaginary parts of dielectric constant (ɛʹ, ϵ״) and dielectric loss tangent (tan δ) are determined in the frequency range of 20 Hz–1 MHz. It was observed that both real and imaginary parts of the dielectric constant and tanδ decrease with the increase of frequency on the basis of Wagner and Koop's theory. [ABSTRACT FROM AUTHOR]

Y-type hexa-ferrite Sr 1.8 Sm 0.2 Co 2 Ni 1.50 Fe 10.50 O 22 was synthesized via micro-emulsion route. Ferrite/PST composites were obtained by mixing the different ferrite ratio in the pure PST matrix. The microstructure was examined by scanning electron microscopy (SEM) and exhibited heterogonous distribution of grains. A keen observation of these SEM images revealed that the grain morphology changes noticeably with increasing ferrite filler contents. The electrical modulus, Cole–Cole plots and quality factor of ferrite polymer composites have been investigated in the frequency range (1 MHz to 3 GHz). The field dependent magnetic properties of the prepared samples were investigated at room temperature by using vibrating sample magnetometer (VSM). The shape of hysteresis loops and linearity of M s , M r , H c values vs. ferrite contents unfold that the ferrite nanoparticles are evenly dispersed within the composite. The occurrence of resonance at high frequency suggests that the present investigated composite samples are best candidate for multilayer chip inductors. [ABSTRACT FROM AUTHOR]

Polycrystalline ferrites with chemical formula MgY 2 x Fe 2−2 x O 4 ( x =0.0 to 0.12) have been fabricated by a double sintering ceramic technique. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Impedance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. A slight increase in lattice constant is observed for x =0.02 and thereafter it decreased for higher Y-contents. The increase in lattice constant is attributed to the difference in ionic radii of the cations involved and decrease led to the formation of secondary phase (YFeO 3 ). The substitution of yttrium impedes the grain growth. The resistivity at 298 K was significantly enhanced as the Y 3+ was increased. The FTIR band positions in the range of 370–1100 cm −1 exhibited two main absorption bands. These bands confirmed the completion of solid state reaction. As the Yttrium contents were increased the dielectric parameters were greatly influenced. Both the observed/optimized electrical and dielectric parameters suggested the potential use of the Y-doped MgFe 2 O 4 ferrites in high frequency devices fabrication. [ABSTRACT FROM AUTHOR]

Abstract: Single phase nanostructured (Eu–Ni) substituted Y-type hexaferrites with nominal composition of Sr2Co2−x Ni x Eu y Fe12−y O22 (x=0.0–1, y=0.0–0.1) were synthesized by the microemulsion method. Temperature dependent DC electrical conductivity and drift mobility were found in good agreement with each other, reflecting semiconducting behavior. The presence of Debye peaks in imaginary electric modulus curves confirmed the existence of relaxation phenomena in given frequency range. The AC conductivity follows power law, with exponent (n) value, ranges from 0.81–0.97, indicating that the mechanism is due to polaron hopping. In the present ferrite system, Cole–Cole plots were used to separate the grain and grain boundary effects. Eu–Ni substitution leads to a remarkable rise of grain boundary resistance as compared to the grain resistance. As both AC conductivity and Cole–Cole plots are the functions of concentration, they reveal the dominant contribution of grain boundaries in the conduction mechanism. It was also observed that the AC activation energy is lower than the DC activation energy. Appreciable improved values of quality factor suggested the possible use of these synthesized materials for power applications and high frequency multilayer chip inductors. [Copyright &y& Elsevier]

Highlights: [•] Single phase nanostructured Sr2Co2−x Ni x Eu y Fe12−y O22 were synthesized by the microemulsion method. [•] The materials show semiconducting behavior. [•] The high resistivity makes these materials useful for high frequency applications. [•] The Curie temperature decreases with the substituents. [ABSTRACT FROM AUTHOR]

Highlights: [•] The decreasing trend of saturation magnetization is attributed to the weakening of exchange interactions. [•] The change in lattice constant at x >0.04 indicated the solubility limit of Gd in the spinel lattice. [•] The high coercive Li–Mg ferrites may be suitable for high frequency microwave absorption. [Copyright &y& Elsevier]

Abstract: Eu substituted MnZn-ferrites with nominal composition Mn0.78Zn0.22Eu x Fe(2−x)O4 (x=0.0, 0.02, 0.04, 0.06, 0.08 and 0.10) were prepared by co-precipitation technique. The effect of Europium substitution on electrical transport properties of Mn–Zn ferrites is reported. XRD analysis reveals fcc phase in all the samples along with few traces of second phase. The lattice constant shows decreasing trend with the substitution of Eu due to partial solubility of Eu-ions in the lattice. Room temperature resistivity both at 10 and 20V shows on average an increasing trend. This increase in resistivity is attributed to the unavailability of Fe+3 ions in the lattice due to Eu-substitution. The dc resistivity decreases with temperature for all the samples at 10V and 20V indicating the semiconducting behavior of these samples. Room temperature dc resistivity and activation energies show similar trend both at 10V and 20V indicating that the samples with high resistivity have high activation energies and vice versa. The dielectric constant (ε′), complex dielectric constant (ε″) and loss tangent of these samples decreased with the increase of Eu-concentration, following the Maxwell–Weigner model. [Copyright &y& Elsevier]

We investigated electrical properties of nanostructured LaSrFeO (0 ≤ x ≤ 1) from 300 K-400 K. The nanostructured LaSrFeO (0 ≤ x ≤ 1) was synthesized by citrate gel method requiring no pH control. X-ray diffraction pattern showed that single phase LaFeO with an orthorhombic structure was formed. The structure changed into rhombohedral for x = 0.5 and it became cubic for x = 1.0. For x ≤ 0.5, our material showed non-linear current-voltage characteristics and for x > 0.5 it showed linear current-voltage characteristics. Poole Frenkel type conduction mechanism was found to be operative in LaFeO from 300 K-400 K. The experimental values of field-lowering coefficient were by 2.56-6.41 times higher than the predicted value and were attributed to the presence of localized fields. The increase in conductance with Sr content was due to formation of Fe ions in addition to Fe with the increase in Sr content. Impedance spectroscopy and ac conductivity analysis of LaSrFeO (0 ≤ x ≤ 1) was also carried out in the temperature range from 300 K-400 K and frequency was varied from 20 Hz - 2 MHz. The ac conduction followed the correlated barrier hopping model in LaSrFeO. [ABSTRACT FROM AUTHOR]

• A series of R-type hexagonal ferrites were prepared by Sol-Gel method. • The XRD analysis showed that the R-type hexagonal structure. • The c/a ratio of these samples falls in the range of R-type hexagonal ferrites. • The dielectric properties changes with the increase of Pr3+ contents. • The peculiar magnetic properties were observed with Pr substitution. A series of rare earth Pr3+ element substituted, Sr 1-x Pr x Mn 2 Fe 4 O 11 (x = 0, 0.02, 0.06, 0.1) R-type hexagonal ferrites has been synthesized by adopting the Sol-gel method. The influence of Pr-substitution on its structural, electrical, dielectric and magnetic behavior was examined. XRD patterns indicate the single phase for all the samples. The lattice parameters and unit cell volume changed with the substitution of Pr3+ contents. The electrical resistivity of the sample significantly varied with the substitution of Pr3+ ions. The sample with the Pr3+ concentration x = 0.1 was observed to have highest resistivity among the others. The dielectric constant was found to decrease at high frequencies for all samples. The tangent loss revealed the hopping type conduction between Fe3+ and Fe2+ sites. The increase in AC conductivity was observed as a function of frequency. The sample with concentration x = 0.1 revealed the maximum value of polarization. A peculiar magnetic trend was observed for all samples upon the substitution of Pr-contents. The unsubstituted sample exhibited the soft ferrimagnetic properties while the paramagnetic behavior was observed for Pr concentration x = 0.02 and last two concentrations (x = 0.06 and 0.1) unveiled the superparamagnetic nature. [ABSTRACT FROM AUTHOR]