Preparation of multiferroic composites of BaTiO3–Ni0.5Zn0.5Fe2O4 ceramics

Magneto-electric coupling in ceramic composites formed by ferroelectric and ferromagnetic phases can be obtained via an adequate mechanical coupling between the individual piezoelectric and magnetostrictive phases (product property). In the present work, the possibility of forming diphase ferroelectric–ferromagnetic ceramics has been investigated. Composites of xBaTiO₃–(1 − x)Ni_0.5Zn_0.5Fe₂O₄ with x = 0.5, 0.6 and 0.7 were prepared according two different procedures: (i) by direct mixing powders of perovskite BaTiO₃ and Ni_0.5Zn_0.5Fe₂O₄ spinel prepared by solid state and (ii) by coprecipitating Fe^III–Ni^II–Zn^II nitric salts in a NaOH solution in which the BaTiO₃ powders were previously dispersed. Optimum processing parameters for good homogeneity, densification and for a reduction of the chemical reactions at the interfaces ferroelectric-ferrite were found. A temperature and composition-dependent magnetic order is present in all the composites, with a dilution effect of the magnetisation due to the presence of the non-ferromagnetic phase. A diffuse ferroelectric–paraelectric transition due to the BaTiO₃ phase was identified by the temperature-dependence of the permittivity and losses, showing that at room temperature the material preserves a ferroelectric order. The interfaces play important roles in the dielectric properties, causing space charge effects and Maxwell–Wagner relaxation, particularly at low frequencies and high temperatures. The combined ferroelectric and magnetic ordering will result in magneto-electric coupling in this material; further investigations are necessary.     

Graphene anchored Ce doped spinel ferrites for practical and technological applications

Graphene plays a remarkable role as a supporting material for the fabrication of a variety of nanocomposites. This work presents the fabrication of graphene-based Ce doped Ni–Co (Ni_0.5Co_0.5Ce_0.2Fe_1.8O₄/G) ferrite nanocomposites. Ni_0.5Co_0.5Fe₂O₄ and Ni_0.5Co_0.5Ce_0.2Fe_1.8O₄ were prepared using sol gel method. However, Ce doped Ni–Co spinel nanoferrite was chemically anchored on the surface of graphene. Different characterizations techniques were adopted to investigate the variations in the properties of ferrite composite due to the incorporation of graphene. Thermal analysis revealed 18% heat weight loss of Ce doped Ni–Co ferrite sample during treatment up to 1000 °C respectively. X-ray diffraction analysis depicted the presence of spinel phase structure of all synthesized nanocomposites. Fourier transform infrared analysis revealed two absorption bands of tetrahedral and octahedral sites of the spinel phase and presence of graphene contents in the Ni_0.8Ce_0.2CoFeO₄/G composite. FESEM images revealed an increased agglomeration due to the presence of graphene in the Ce doped Ni–Co ferrite composites. Graphene based Ce doped Ni–Co ferrite nanocomposite showed highest conductivity (4.52 mS/cm) than other ferrite composites. Magnetic characteristics showed an improvement in the Ni–Co ferrite sample by the substitutions of Ce³⁺ ions and graphene contents. The improvement in the properties of these nanocomposites makes them potential material for many applications such as fabrication of electrodes, energy storage and nanoelectronics devices.     

Low-loss insulating-conductive ceramic composite with giant permittivity and high permeability using glass phase as separating layer

The control of dielectric loss in insulating-conductive ceramic composites is of great significance for the enhancement of the comprehensive performance of next-generation devices. In this work, a low-activity precursor co-sintering method was proposed to prepare low-loss BaTiO₃(BTO)/Ni_0.5Zn_0.5Fe₂O₄(NZFO) ceramic composite by using 2PbO–B₂O₃(PBO) glass as insulating layer. XRD and SEM were used to reveal the phase composition and the morphology of the composite. Results showed that the conductive networks can be successfully cut off by PBO glass separating layer inside the composite (1−x)BTO/xNZFO where x is the molar fraction of NZFO ferrite, giving rise to decreased dielectric loss in a wide compositional range between x=0.1–0.7 while retaining considerable effective permittivity and initial permeability. Excess amount of PBO glass is not favorable for the formation of separating layer due to the chemical reactions occurring between the constituent phases and the glass phase; meanwhile, accompanied by the decrement in dielectric loss, the initial permeability of the composite decreases linearly with increasing PBO content.     

Dielectric,magnetic and magnetoelectric properties of Ni0.5Zn0.5Fe2O4+Pb(Zr0.48Ti0.52)O3 composite ceramics

Magnetoelectric composite ceramics of spinel ferrite Ni_0.5Zn_0.5Fe₂O₄ (NZFO) with high magnetic permeability and tetragonal perovskite Pb(Zr_0.48Ti_0.52)O₃ (PZT) with high piezoelectric constant were synthesized by common solid state reaction method. XRD and SEM showed that high dense composite ceramics without any foreign phases were obtained. The ceramics showed excellent dielectric and magnetic properties, which were stable in a large frequency range. The dielectric peak became wider with the ferrite content in the permittivity spectrum with temperature. With the increase in the ferrite content, the magnetic Curie temperature shifted to higher temperature and closed to that of the pure ferrite. In addition, the magnetoelectric coefficient enhanced as the increase in the ferrite content. The properties of the composite ceramics could be adjusted by the ferrite content. These research results provided a powerful experimental basis for the sensor and transducer in microelectronic and microwave devices.     

Selective synthesis of 3-picoline via the vapor-phase methylation of pyridine with methanol over Ni1-x Co x Fe2O4 (x = 0, 0.2, 0.5, 0.8 and 1.0) type ferrites

A series of Ni–Co ferrites with the general formula Ni_1-x Co _x Fe₂O₄ (x = 0, 0.2, 0.5, 0.8 and 1.0) was prepared by a low-temperature hydroxide coprecipitation route. The catalyst systems were characterized by adopting various physico-chemical techniques. Alkylation of pyridine with methanol was carried out in a down-flow vapor-phase reactor. The influence of surface acid–base properties, cation distribution in the spinel lattice and various reaction parameters are discussed. It was observed that the systems possessing x values 0.5 are selective for 3-picoline formation, whereas the ones with x values 0 and 0.2 give a mixture of 2- and 3-picolines. Pyridine conversion increased with the progressive substitution of Ni²⁺ ions by Co²⁺ ions. Cation distribution in the spinel lattice influences their acidic and basic properties, and these factors have been adequately considered as helpful to evaluate the activity of the systems.     

Processing and characterization of nano-magnetic Co0.5Ni0.5Fe2O4 system

Various techniques such as X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron micrographs (SEM), energy dispersive X-ray (EDX) and a vibrating sample magnetometer (VSM) were used to investigate the structural, morphological, and magnetic properties of spinel Co_0.5Ni_0.5Fe₂O₄ system. XRD and IR analyses enabled us to determine the functional group and structural parameters of Co_0.5Ni_0.5Fe₂O₄. EDX measurements showed the concentrations of O, Ni, Fe, and Co species involved in Co_0.5Ni_0.5Fe₂O₄ specimen from the uppermost surface to the bulk layers. The magnetization and coercivity of the as synthesized composite were 77 emu/g and 128 Oe, respectively.     

Mg0.5Ni0.5Fe2O4 nanoparticles as heating agents for hyperthermia treatment

In the present work, Mg_0.5Ni_0.5Fe₂O₄ nanopowders were prepared by a sol-gel combustion method. The magnetic properties, heat generation ability in an AC magnetic field and cytotoxicity of the mixed ferrite nanopowders were investigated. The results showed that the powders have crystalline spinel structure with a particle size in the range of 20-90 nm. Maximum saturation magnetization (Ms) of 51 emu/g was obtained for the Mg_0.5Ni_0.5Fe₂O₄ nanoparticles calcined at 900°C. The results showed that, the coercivity (Hc) of the Mg_0.5Ni_0.5Fe₂O₄ initially increases up to 700°C and then decreases with increasing temperature, whereas the Ms of the samples continuously increases. The Mg_0.5Ni_0.5Fe₂O₄ sample exhibited a temperature increase up to 45°C during 10 minutes in the exposure of magnetic field of 200 Oe. By increasing the viscosity of ferrofluid, the heat generation ability of nanoparticles reduced up to 9% at magnetic field of 200 Oe. Cell compatibility of the ferrite powders was studied by MTT assay using MG63 cell line proliferation. MTT results showed that calcination temperature of the Mg_0.5Ni_0.5Fe₂O₄ nanoparticles significantly affects the cell compatibility.     

Ferroelectric and magnetic properties in (1−x)BiFeO3–x(0.5CaTiO3–0.5SmFeO3) ceramics

Multiferroic ceramics were prepared and characterized in (1?x)BiFeO₃–x(0.5CaTiO₃–0.5SmFeO₃) system by a standard solid‐state reaction process. The structure evolution was investigated by X‐ray diffraction and Raman spectrum analyses. The refinement results confirmed the different phase assemblages with varying amounts of polar rhombohedral R3c and nonpolar orthorhombic Pbnm as a function of the substitution content. In the compositions range of 0.2≤x≤0.5, polar R3c and nonpolar Pbnm coexisted, which was referred to polar‐to‐nonpolar morphotropic phase boundary (MPB). According to the dielectric and DSC analysis results, the ceramics with x≤0.2 changed to diffused ferroelectric, and the ferroelectric properties were enhanced significantly. Two dielectric relaxations were detected in the temperature range of 200‐300 K and 500‐700 K, respectively. The high‐temperature dielectric relaxation was attributed to the grain‐boundary effects. While the low temperature dielectric relaxation obtained in the samples with x=0.3‐0.5 was related to the charge transfer between Fe²⁺ and Fe³⁺. The magnetic hysteresis loops measured at different temperature indicated the enhanced magnetic properties in the present ceramics, which could be attributed to the suppressed cycloidal spin magnetic structure by Ti ions. In addition, the rare‐earth Sm spin moments might also affect the magnetic properties at relatively lower temperature.     

Effect of bimetallic (Ni and Co) substitution on magnetic properties of MnFe2O4 nanoparticles

Nickel and cobalt substituted manganese ferrite nanoparticles (NPs) with the chemical composition Ni_xCo_xMn_1–2xFe₂O₄ (0.0≤x≤0.5) NPs were synthesized by one-pot microwave combustion route. The effect of co-substitution (Ni, Co) on structural, morphological and magnetic properties of MnFe₂O₄ NPs was investigated using XRD, FT-IR, SEM, VSM and Mössbauer spectroscopic techniques. The cation distribution of all products were also calculated. Both XRD and FT-IR analyses confirmed the synthesis of single phase spinel cubic product for all the substitutions. Lattice constant decreases with the increase in concentration of both Co and Ni in the products. From ⁵⁷Fe Mössbauer spectroscopy data, the variations in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values with Mn²⁺, Ni²⁺ and Co²⁺ substitution have been determined. While the Mössbauer spectra collected at room temperature for the all samples are composed of magnetic sextets, the superparamagnetic doublet is also formed for MnFe₂O₄ and Ni_0.2Co_0.2Mn_0.6Fe₂O₄ NPs. The magnetization and Mössbauer measurements verify that MnFe₂O₄ and Ni_0.2Co_0.2Mn_0.6Fe₂O₄ NPs have superparamagnetic character. The saturation and remanence magnetizations, magnetic moment and coercive field were determined for all the samples. Room temperature VSM measurements reveals saturation magnetization value close to the bulk one. It has been observed that the saturation magnetization and coercive field increase with respect to the Ni and Co concentrations.     

Magneto-dielectric laminated Ba(Fe0.5Nb0.5)O3-Bi0.2Y2.8Fe5O12 composites with high dielectric constant and high permeability

Magneto-dielectric laminated ceramic composites of xBa(Fe_0.5Nb_0.5)O₃-(1-x)Bi_0.2Y_2.8Fe₅O₁₂(BFN-BYIG) with high volume fractions of the giant dielectric constant material BFN (x=10, 30, 50, 70 wt%) were fabricated by the solid-state sintering method. Microstructure, dielectric and magnetic properties of the composites were investigated. The composites possess stable dielectric properties in the frequency range from 100 Hz to 1 MHz with high dielectric constant and low dielectric loss. The maximum permeability of the magneto-dielectric laminated composites reaches up to about 25. And the magnetic behaviors are strongly dependent on the mass ratio of BYIG. The results indicate that such multilayer structures of BFN/BYIG can enhance the permeability and decrease the dielectric and magnetic loss efficiently.     

Thermal stability and local atomic structure of (Na0.5K0.5)NbO3 doped BaTiO3 ceramics

Dielectric properties of x(Na_0.5K_0.5)NbO₃–(1−x)BaTiO₃ (x=0.00 and 0.06) specimens were investigated in terms of changes in local atomic structure, according to the phase transition by elevating the overall temperature. A 0.06(Na_0.5K_0.5)NbO₃–0.94BaTiO₃ (NKN–BT) specimen exhibited enhanced temperature stability along with an increased dielectric constant. The degree of reduction in tetragonality (c/a) at the Curie temperature was smaller in NKN–BT compared to that in pure BaTiO₃, as calculated by Rietveld refinement. From a comparison of the pre-edge region in the Ti K-edge, it was determined that the off-center displacement of the Ti atom was also raised to 13.4% through NKN substitution, with a change in local orientation from the [001] to the [111] directions. The substitution by NKN, which has a different ionic radius and electrical charge compared with BaTiO₃, causes structural distortion of the TiO₆ octahedra in the NKN–BT lattice, resulting in local polarization. These structural changes lead to the temperature stability of the dielectric constant and an overall improvement in the electrical properties of BaTiO₃.     

Magnetic and ferroelectric domain structures in BaTiO3–(Ni0.5Zn0.5)Fe2O4 multiferroic ceramics

BaTiO₃–(Ni_0.5Zn_0.5)Fe₂O₄ composites prepared by co-precipitation were investigated. The macroscopic magnetic properties derived from the magnetic phase (low coercivity, almost no M(H) hysteretic behavior and high permeability) are preserved in the composite. The dielectric properties are strongly influenced by interface phenomena (Maxwell-Wagner), due to the local electrical inhomogeneity. At low frequencies, the composites present thermally activated conductivity and relaxation, while at 1 MHz permittivity of around 500 and tan δ < 8% is obtained at room temperature. The multiferroic character was demonstrated at nanoscale by the presence of the magnetic and ferroelectric domain structure in the same region. Imprint polarisation in the regions corresponding to the ferroelectric phase is found, as result of an internal electrical field created at the interfaces between the (Ni,Zn)-ferrite and BaTiO₃ regions.     

Low‐Temperature Sintering Li2MoO4/Ni0.5Zn0.5Fe2O4 Magneto‐Dielectric Composites for High‐Frequency Application

The coexistence of Li₂MoO₄ (LMO) and Ni_0.5Zn_0.5Fe₂O₄ (NZO) has been proven and their low‐temperature‐sintered magneto‐dielectric composites (1?x)LMO–xNZO (volume fraction factor x = 0.1, 0.3, 0.5, 0.7) were prepared by the conventional solid‐state reaction method and were sintered below 700°C. It is found that the optimal sample (x = 0.5) has good and relatively stable magneto‐dielectric performance in the frequency range from 10 MHz to 1 GHz with permittivity between 7.14 and 6.84, dielectric loss tangent between 0.09 and 0.02, and permeability between 5.23 and 3.30, magnetic loss tangent between 0.06 and 0.65, respectively. Furthermore, the verified chemical compatibility with silver indicates that the LMO–NZO ceramics are potential for low‐temperature cofired ceramic application and their multifunctional magneto‐dielectric properties also make them for potential applications in electronic devices.     

Effects of BiMO3 on dielectric,ferroelectric, and piezoelectric properties of perovskite lead‐free piezoelectric BaTiO3–(Bi0.5Na0.5)TiO3 ceramics

New lead‐free piezoelectric ceramics of 0.9BaTiO₃–(0.1?x)(Bi_0.5Na_0.5)TiO₃–xBiMO₃, M=Al and Ga, where x=0.00‐0.10, were fabricated by the solid‐state reaction technique. The effect of BiMO₃ contents on the perovskite structure, phase transition, and dielectric, ferroelectric, and piezoelectric properties was investigated. X‐ray diffraction patterns showed that the ceramics exhibit a monophasic perovskite phase up to x=0.06, suggesting stabilized perovskite structures with B‐site aliovalent substitutions. Compositional‐dependent phase transitions were observed from tetragonal to pseudo‐cubic phase with increasing BiMO₃ amounts. Al³⁺ ions were found to stabilize the transition temperature of the ceramics, while significantly decreasing transition temperature, and a change in the dielectric peak were found with an increasing amount of Ga³⁺. Regarding Al³⁺ substitution, the remanent polarization (P_r) values were found to decrease slightly with the Al³⁺ amount. With regard to Ga³⁺ substitution, P_r values decreased with the Ga³⁺ amount up to 0.06 and then increased slightly. The ceramics became softer with a higher degree of substitution according to the lower coercive field (E_c), when compared with 0.9BaTiO₃–0.1(Bi_0.5Na_0.5)TiO₃ ceramics. Ceramics with a lower degree of substitution and tetragonal phase showed butterfly strain loops that correlated with normal ferroelectric behavior.     

Preparation and investigation of structure,magnetic and dielectric properties of (BaFe11.9Al0.1O19)1-x - (BaTiO3)x bicomponent ceramics

(BaFe_11.9Al_0.1O₁₉)_1-x - (BaTiO₃)_x with x?=?0, 0.25, 0.5, 0.75 and 1 bicomponent ceramics has been prepared from single-phase compounds of BaFe_11.9Al_0.1O₁₉ (x?=?0) (BFO) and BaTiO₃ (x?=?1) (BTO) by a standard ceramic technique. The constituent materials have been chosen considering their perspective ferrimagnetic and ferroelectric properties, respectively for BFO and BTO. Moreover, Ba-hexaferrites are reported to exhibit ferroelectricity at room temperature as well, and the combination of two ferroelectric phases is of interest. Systematic investigations of the structural, magnetic and dielectrical properties versus chemical composition (x) have been performed. The ferrimagnetic phase transition temperature is almost independent of the BTO content, which is determined by intensity of the Fe³⁺-O^2--Fe³⁺ indirect superexchange interactions in the BFO hexaferrite phase. However, the coercivity of composite samples is lower due to the contribution of the microstructure-dependent shape anisotropy to the total magnetic anisotropy energy. The permittivity vs. temperature behavior confirmed the existence of two ferroelectric phase transitions corresponding to structural phase transitions in BTO at ~ 400?K and BFO at ~ 700?K. It has been observed that the dielectrical properties of composite samples, including the temperatures of the phase transitions, critically depended on concentration x which affects the composite microstructure. This behavior has been discussed in terms of microstructure analysis and such parameters as the grain size, porosity and density.     

FexCo0.5−xNi0.5-SDC anodes for low-temperature solid oxide fuel cells

Trimetal alloys, Fe_xCo_0.5−xNi_0.5 (x = 0.1, 0.2, 0.25, 0.3, 0.4), were studied as anodes for low-temperature solid oxide fuel cells (LT-SOFCs) based on GDC (Ce_0.9Gd_0.1O_1.95) electrolytes. The alloys were formed by in situ reduction of Fe_xCo_0.5−xNi_0.5O_y composites, which were synthesized using a glycine-nitrate technique. Symmetrical cells consisted of Fe_xCo_0.5−xNi_0.5-SDC electrodes and GDC electrolytes, and single cells consisted of Fe_xCo_0.5−xNi_0.5-SDC (Ce_0.8Sm_0.2O_1.9) anodes, GDC electrolytes, and SSC (Sm_0.5Sr_0.5CoO₃)-SDC cathodes were prepared using a co-pressing and co-firing process. Interfacial polarization resistances and I-V curves of these cells were measured at temperature from 450 to 600 °C. With Fe_0.25Co_0.25Ni_0.5-SDC as anodes, the cells showed the lowest interfacial resistance and highest power density. For example, at 600 °C, the resistance was about 0.11 Ω cm² and power density was about 750 mW cm⁻² when humidified (3% H₂O) hydrogen was used as fuel and stationary air as oxidant. Further, the cell performance was improved when the molar ratio of Fe:Co:Ni approached 1:1:2, i.e. Fe_0.25Co_0.25Ni_0.5. In addition, higher power density and lower interfacial resistance were obtained for cells with the Fe_0.25Co_0.25Ni_0.5-SDC anodes comparing to that with Ni-SDC anodes, which have been usually used for LT-SOFCs. The promising performance of Fe_xCo_0.5−xNi_0.5 as anodes suggests that trimetallic anodes are worth considering for SOFCs that operate at low-temperature.     

Two phase Mg0.7Cd0.3Fe2O4–BaTiO3 composite ceramics with excellent magneto-dielectric properties for antennas in GHz band

Two phase-based composites comprising barium titanate (BaTiO₃) and spinel magnesium ferrite (1-x)Mg_0.7Cd_0.3Fe₂O₄ +xBaTiO₃ (x = 0.00, 0.03, 0.06, 0.09, and 0.12) were investigated. The phase structure revealed the coexistence of the perovskite BaTiO₃ and spinel MgFe₂O₄ phases. The microstructural analysis indicated that the average crystallite size initially increased and then decreased, as the increase in x weakened magnetisation, decreased saturation magnetisation (from 47.5 to 35.9 emu/g) and coercivity (150–0 Oe) were obtained, resulting in reduced permeability at low frequency. The permittivity gradually increased owing to tuning by barium titanate, which has strong dielectric properties, promising a relatively large miniaturisation factor. Further, low magnetic loss (tan δ_μ ∼10⁻²) and dielectric loss (tan δ_ε ∼ 10⁻² to 10⁻³) guarantee high quality factor. The low losses and enhanced dielectric properties of the as-synthesised composites could be conducive to improving the behaviour of such magneto-dielectric composite systems in microwave applications.     

Effect of Ni2+ substitution on structural,magnetic, dielectric and optical properties of mixed spinel CoFe2O4 nanoparticles

Nanoparticles of Co_1−xNi_xFe₂O₄ with x=0.0, 0.10, 0.20, 0.30, 0.40 and 0.50 were synthesized by co-precipitation method. The structural analysis reveals the formation of single phase cubic spinel structure with a narrow size distribution between 13–17 nm. Transmission electron microscope images are in agreement with size of nanoparticles calculated from XRD. The field emission scanning electron microscope images confirmed the presence of nano-sized grains with porous morphology. The X-ray photoelectron spectroscopy analysis confirmed the presence of Fe²⁺ ions with Fe³⁺. Room temperature magnetic measurements showed the strong influence of Ni²⁺ doping on saturation magnetization and coercivity. The saturation magnetization decreases from 91 emu/gm to 44 emu/gm for x=0.0–0.50 samples. Lower magnetic moment of Ni²⁺ (2 µ_B) ions in comparison to that of Co²⁺ (3 µ_B) ions is responsible for this reduction. Similarly, overall coercivity decreased from 1010 Oe to 832 Oe for x=0.0–0.50 samples and depends on crystallite size. Cation distribution has been proposed from XRD analysis and magnetization data. Electron spin resonance spectra suggested the dominancy of superexchange interactions in Co_1−xNi_xFe₂O₄ samples. The optical analysis indicates that Co_1−xNi_xFe₂O₄ is an indirect band gap material and band gap increases with increasing Ni²⁺ concentration. Dispersion behavior with increasing frequency is observed for both dielectric constant and loss tangent. The conduction process predominantly takes place through grain boundary volume. Grain boundary resistance increases with Ni²⁺ ion concentration.     

Structural and electromagnetic properties of Ni0.5Zn0.5HoxFe2-xO4 ferrites

Ni-Zn ferrites with a nominal composition of Ni_0.5Zn_0.5Ho_xFe_2-xO₄ (x = 0–0.06) were prepared by conventional solid state reaction through using analytical-grade metal oxides powders as raw materials. The phase composition, microstructure, magnetic properties and dielectric performance of the as-prepared samples were investigated. The doped Ho³⁺ ions could enter into the crystal lattice of the resultant spinel ferrites, causing the expansion of the unit cell, reaching a saturated state when x = 0.015; and the additional Ho³⁺ ions would form a foreign HoFeO₃ phase at the grain boundary. The grain size and densification of the samples initially decreased after a small amount of Ho³⁺ ions was doped, but then increased with more Ho³⁺ ions added. The saturation magnetization decreased gradually with increasing substitution level of Ho³⁺ ions. The Curie temperature and coercivity raised initially and declined later with increasing content of Ho³⁺ ions in the samples, reaching their maximums of 305 °C with x = 0.015 and 2.99 Oe with x = 0.03, respectively. The variation of complex permeability versus Ho³⁺ ions substitution level presented an opposite trend to that of coercivity. The dielectric loss increased slightly after the introduction of a small amount of Ho³⁺ ions, but reduced significantly with more Ho³⁺ ions doped.     

Investigations of Structural and Magnetic Properties of Nanostructured Ni0.5+xZn0.5‐xFe2O4 Magnetic Feeders for CSEM Application

Marine CSEM is a new technique for detection of deep target hydrocarbons. Aluminum EM antenna was developed, and nanostructured NiZn magnetic feeders were used to increase the field strength from EM antenna for deep hydrocarbons. The doping of Ni²⁺ was aimed at the optimization of initial permeability and magnetic losses. Ni_0.5+xZn_0.5‐xFe₂O₄ (x = 0.3) samples sintered at 950°C presented highest initial permeability (106.23) and low magnetic loss (0.0002) as compared to other samples. Due to better magnetic properties, Ni_0.5+xZn_0.5‐xFe₂O₄ (x = 0.3) samples were used as magnetic feeders for EM antenna. Magnitude of EM waves from the antenna increased up to 186%.