Ferrite Li0 Research Articles

Synthesis of New Complex Ferrite Li0.5MnFe1.5O4: Chemical-Physical and Electrophysical Research.

In this article, the sol-gel method was used as a synthesis method, which shows the physicochemical nature of the synthesis of a new complex material, ferrite Li0.5MnFe1.5O4. The structure and composition of the synthesized ferrite were determined by X-ray phase analysis. According to analysis indicators, it was found that our compound is a single-phase, spinel-structured, and syngony-cubic type of compound. The microstructure of the compound and the quantitative composition of the elements contained within it were analyzed under a scanning electron microscope (SEM). Under a scanning electron microscope, microsystems were taken from different parts of Li0.5MnFe1.5O4-type crystallite; the elemental composition of crystals was analyzed; and the general type of surface layer of complex ferrite was shown. As a result, given the fact that the compound consists of a single phase, the clarity of its construction was determined by the topography and chemical composition of the compound. As a result, it was found that the newly synthesized complex ferrites correspond to the formula Li0.5MnFe1.5O4. The particles of the formed compounds have a large size (between 50.0 μm or 20.0 μm and 10.0 μm). Electrophysical measurements were carried out on an LCR-800 unit at intervals of 293-483 K and at frequencies of 1.5 and 10 kHz. An increase in frequency to 10 kHz led to a decrease in the value ε in the range of the studied temperature (293-483 K).

Structural and electrical conduction properties of Y3+ ions substituted Li-Zn-Ti ferrites

Rare earth yttrium substituted lithium ferrites Li0.5Zn0.1Ti0.1Y x Fe2.3– x O4 with nominal composition x = 0.00 to 0.10 in steps of 0.02 was prepared by the conventional ceramic method. The samples were sintered at 1050 °C for 6 h using resistive conventional heating. X-ray diffraction (XRD) patterns confirmed the formation of a single phase with a spinel structure. FTIR studies also confirmed the tetrahedral and octahedral metal-oxygen bonding of the spinel structure. Structural parameters like density, lattice constant, and crystallite size, site distances, bond length distances were measured from XRD data. The crystallite size reduces while the density increased with the progressive substitution of Y3+ ions. The Fe3+ ions at the A and the B sites mainly contributes to the electromagnetic properties of ferrites. Y3+ ions preferably entering the B sites can significantly interfere with the conduction mechanism of lithium ferrites. The objective of the present work is to find out the effect of Y3+ substitution on the structural and electrical conduction response Li-Zn-Ti ferrites. The DC resistivity initially is found to increase for concentration x = 0.04 and then decrease with further substitution. The study of the temperature dependence of DC resistivity depicts two types of conduction mechanisms in the range studied. The results obtained are analyzed and presented in the paper.

Study of physical properties of the Li0.5MgFe1.5O3.5 ferrite nanoparticles.

In the present research study, the structural, optical, magnetic, electrical and dielectrical properties of the spinel ferrite Li0.5MgFe1.5O3.5, synthesized using a sol-gel auto-combustion method were studied. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy revealed that this sample crystallizes in a cubic spinel structure with space group Fd3̄m. Moreover, the optical investigation by UV-visible spectroscopy has revealed that the band gap for our sample is (E g = 2.87 eV), which shows that our compound is a potential candidate for optoelectronic applications. The values of the remanent magnetization M r = 0.13 emu g-1, of the coercive field H C = 4.65 Oe deduced from the hysteresis loop, are very low, suggesting the superparamagnetic behavior of our sample. Additionally, the temperature coefficient of resistance (TCR) is -19% affirmed that Li0.5MgFe1.5O3.5 ferrite is a good candidate for detecting infrared radiation and infrared bolometric applications. Indeed, the activation energies were calculated from the imaginary part of the impedance, the electrical conductivity, and the imaginary part of the modulus, thus demonstrating that the charge carriers involved in the processes of conduction and relaxation are the same.

TG, DSC, XRD, and SEM studies of the substituted lithium ferrite formation from milled Sm2O3/Fe2O3/Li2CO3 precursors

Formation of substituted lithium ferrite Li0.5SmxFe2.5–xO4 (where x = 0.06 and 0.2) from Sm2O3/Fe2O3/Li2CO2 precursors was studied by X-ray diffraction analysis, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The mixture of powders was subjected to preliminary mechanical activation in a planetary mill. We analyzed samples based on the precursors and synthesized at 900 °C for 4 h in a laboratory furnace. It was found that ball milling of the precursors mixture in a planetary mill increases the powder reactivity. In spite of this, no substituted lithium ferrites were formed. It was shown that a two-phase composite that consists of pure lithium ferrite Li0.5Fe2.5O4 and SmFeO3 is formed during synthesis. An increase in the Sm2O3 content in the initial mixture provides an increase in the amount of the formed SmFeO3 phase. The synthesis of Li0.5Fe2.5O4 ferrite was confirmed by XRD analysis data, the Curie temperature (627–630 °C) measured using TG analysis in a magnetic field, and by the presence of an endothermic peak on the DSC curve corresponding to the order–disorder transition in the Li0.5Fe2.5O4 phase.

Lithium ferrite (Li0.5Fe2.5O4): synthesis, structural, morphological and magnetic evaluation for storage devices

Lithium ferrite Li0.5Fe2.5O4 has been synthesized by the use of the sol–gel technique. X-ray diffractometer (XRD) has been employed to confirm the crystal structure of spinel ferrites. No impurity peaks are detected in XRD graph, which confirms single phase crystal structure. The evaluation of grain size and analysis of external surface morphology of synthesized lithium ferrites has been done by scanning electron microscope (SEM). Average grain size was about equal to 131 nm. Energy dispersive x-ray spectra showed all the elements were present in required proportions. Magnetic characteristics such as saturation magnetization (Ms), remanence (Mr), and coercive force (Hc) have been measured from MH loops. Saturation magnetization has been measured to be 43.69 emu/by law of approach to saturation. The coercivity value lies in the range of few hundred Oersted which is vital condition for electromagnetic materials. Cyclic Voltammetry (CV) measurements were made, to know about the electrochemical performance of the material. CV results show that with the increase in scan rate specific capacitance decreases and the area of the loop increases which is promising for the formation of super capacitors and lithium-ion batteries (LIB's).

The magnetic properties dependence on temperature of Li-ferrite nanoparticle

The chemical formula Li0.5Fe2.5O4 of lithium ferrite prepared by two different chemical methods mentioned as low temperature solid state reaction (LTSSR) and modified combustion method (MCM). The samples showed nanoparticle scale with spinal structure. The magnetic analyses have done by the vibrating sample magnetometer VSM device, and both samples have the same magnetic properties represented by the magnetic saturation, remanence magnetization, and coercive magnetic field. The shape of hysteresis loop showed a soft ferrite and its area decreased with temperature increasing. On the other hand, the magnetic susceptibility decreased with increasing temperature for both samples of ferrite Li0.5Fe2.5O4 prepared. The sample of LTSSR exhibited a magnetic moment of about 0.410-3 JT-1 at applied magnetic field 50 kOe which is approaching the same for the sample prepared by MCM method.

Crystal Chemistry and Magnetic Properties of Polycrystalline Spinel Ferrites Li0.33Fe2.29Zn0.21Mn0.17O4

Crystal Chemistry and Magnetic Properties of Polycrystalline Spinel Ferrites Li0.33Fe2.29Zn0.21Mn0.17O4

Enhanced microwave absorption performance of graphene/doped Li ferrite nanocomposites

In the present study, Microwave absorbing Li-Sr, Li-Co ferrite nanoparticles and RGO/Li-Sr, RGO/Li-Co ferrite nanocomposites containing Li ferrite and reduced graphene oxide (RGO) were synthesized to further improve the microwave absorption performance of Li ferrite nanoparticles (LiFe5O8). The Li-Sr and Li-Co nanoparticles were synthesized by thermal treatment method, the RGO/Li-Sr and RGO/Li-Co nanocomposites were obtained by a polymerization method and were characterized by different techniques. The electromagnetic wave absorption properties of the samples were evaluated by vector network analyzer (VNA) in the frequency range of 2–18 GHz. The magnetic and dielectric loss, impedance matching, and electromagnetic wave absorption of the samples are significantly improved through the addition of RGO. Experimental results revealed that the RGO/Li-Co nanocomposite considerably increased microwave absorption. The minimum reflection loss (RL) of RGO/Li-Co also was found to reach −46.80 dB at the thickness of 3 mm and the effective absorption bandwidth (≤-10 dB) amounted to 6.80 GHz (from 10.52 to 17.32 GHz), which was much higher in comparison with pure Li and Li-Co ferrites nanoparticles. Due to the synergistic effect between magnetic loss and dielectric loss and the good impedance matching, the RGO/Li-Co nanocomposite may be regarded as a new candidate for microwave absorbing materials characterized with a broad effective absorption bandwidth at thin thicknesses.

Effect of sintering temperature on the synthesis of LiZnMnFe microwave ceramics with controllable electro/magnetic properties

Self-propagating high-temperature (SPHT) assisted method was successfully used to obtain soft magnetic ceramics based on the nanostructured powder of multicomponent lithium ferrite Li0·45Zn0·08Mn0·06Fe2·41O4. The influence of various temperature modes of sintering (900–1075 °C) on the microstructure, morphology, phase composition, and magnetic and electromagnetic properties of the initial powder and final ceramic products was analyzed in detail by methods of scanning electron microscopy, transmission electron microscopy, energy-dispersive and atomic absorption spectroscopy, thermogravimetry, calorimetry, X-ray diffractometry, induction magnetometry and measurement of electromagnetic parameters. It was shown that the particle size of the initial powder is 40 nm and depending on the sintering modes, it is possible to obtain lithium-zinc-manganese ferrite ceramics with an average grain size from 0.35 to 2.96 μm and porosity varying from 3.8 to 23.3%. The coercive force, residual induction, and saturation induction of the obtained samples were 51.3–816.6 A/m, 761.40–2131.30 G, and 1234.28–3431.71 G, respectively. It was found that the sample sintered at a temperature of 1075 °C for 8 h demonstrated the most pronounced soft magnetic behavior. The electromagnetic characteristics of the obtained samples also depended on the selected sintering mode and reached their maximum for ceramics sintered at a temperature of 1075 °C (ϵ’ = 11.52; ϵ” = 6.32⸱10−3; tan δϵ = 5.49⸱10−4; ΔH = 280 Oe; ΔHk = 1.87 Oe).

SCS-assisted preparation of magnetically soft Li and LiZnMn ferrite nanopowders with enhanced bioavailability and bioactivity suitable for use in food technology

This article provides information about the bactericidal performances of lithium ferrites nanopowders obtained via heat-treatment of amorphous products of solution combustion approach. XRD, EDX, SEM, and VSM were used to investigate morphology features, structural and magnetic parameters. The inhibition zone test with Escherichia coli, Bacillus cereus, and Staphylococcus citreus as the bacterial source was used to investigate the antibacterial performances. It was found that pure single-phase Li and LiZnMn ferrites with an average size of particles − 35 and 44 nm, respectively, are formed under the SCS-assisted method. The investigation of magnetic behavior indicates the magnetically soft nature of the obtained powders with moderate coercivity force (Hc) values equal to 116.1 Oe for Li-ferrite and 54.3 Oe for LiZnMn-ferrite. When studying the antibacterial activity, the inhibition zones were measured as 16-17 mm for E. coli, 15-25 mm in the case of B. cereus, and 13-16 mm for S. citreus, and the findings is the synthesized compositions are suitable for use in the agricultural sector.

Synthesis of uniform LiZnTi ferrite with enhanced magnetic properties through CuO nanoparticle substitution

In this work, a systematic study of the influences of CuO nanoparticle on the crystal structure, morphological characteristics and magnetic parameters of LiZnTi ferrite is present. The CuO-substituted LiZnTi ferrites (Li0.43−x/2Zn0.27Ti0.13CuxFe2.17−x/2O4; 0 ≤ x ≤ 0.25) are synthesized through solid-phase sintering process. XRD results suggest that there is only spinel structure (space group Fd-3m), meaning the CuO nanoparticle has no effect on phase structure. And the phenomenon that left shift of the diffraction peaks is due to larger Cu2+ ions substitution. SEM images show that the ferrites have uniform and compact grain, which indicates the Cu2+ ions substitution does not deteriorate microstructure. Moreover, the relationships between magnetic properties and Cu2+ ions content have been discussed in detail. Finally, a spinel structure LiZnTi ferrite with uniform grain and optimized magnetic parameters (4πMs = 3904.3 G, Br/Bs = 0.87, Hc = 241.2 A/m and Bs = 306.2 mT) is obtained when Fe3+ ions are replaced by Cu2+ ions (i.e., x = 0.15).

Магнитные и радиопоглощающие свойства поликристаллического феррита-шпинели Li-=SUB=-0.33-=/SUB=-Fe-=SUB=-2.29-=/SUB=-Zn-=SUB=-0.21-=/SUB=-Mn-=SUB=-0.17-=/SUB=-0-=SUB=-4-=/SUB=-

Polycrystalline spinel ferrites of the composition Li0.33Fe2.29Zn0.21Mn0.17O4 were synthesized by using the ceramic technology method at sintering temperatures of 950 ° C, 1000 ° C, 1050 ° C, and 1100 ° C. Magnetic hysteresis loops and magnetic permeability of the experimental samples were studied in the range of magnetic fields of -400–400 A/m. In the frequency range of 0.01–7.0 GHz, the behavior of the complex dielectric and complex magnetic permeability, as well as the reflection coefficient on a metal plate, are investigated. It was found that the optimal sintering temperature range for synthesized ferrites is from 1050 ° C to 1100 ° C. It is shown that the spinel ferrite Li0.33Fe2.29Zn0.21Mn0.17O4 intensely absorbs electromagnetic radiation in the frequency range from 0.05 to 7.0 GHz. Possibilities of practical application of the obtained results are discussed.

Influence of li1+ (alkali metal) ion on structural, optical and magnetic properties of nickel ferrite nanomaterials for multifunctional applications

Lithium substituted nickel ferrite nanoparticles, LixNi1-xFe2O4 (x = 0 and 0.5) synthesized using citrate precursor method at a low annealing temperature of 550 °C. The effect of Lithium on structural, morphology, magnetic and optical properties of nanoparticles has been studied. X-ray diffraction measurements show the formation of cubic spinal crystal. The crystallite size were evaluated by Williamson-Hall plot and found to be 26 nm and 24 nm respectively. Monotonically increase in lattice constant and lattice strain was observed with the substitution of Lithium atom. FTIR measurements show, two characteristics absorption peaks of cubic spinel ferrites at range around 580 cm−1 and 470 cm−1 wave number. Morphology of the sample was studied using Scanning Electron Microscopy and found change in agglomeration due to change in antiparticle interaction. The Indirect band gap were found 2.20 eV for Nickel ferrite and 2.28 eV for substituted Li ferrite. Photoluminescence spectra show that strong luminescence in visible range. Magnetic parameter such as remanence, coercivity, and saturation magnetization increases with increase in lithium ion concentration (Mr- 7.57 emu/g- 14.478 emu/g, Hc −178Oe-192Oe and (36.5 emu/g to 41.5 emu/g). Force constant and bond length were found to dependent on Lithium ion. Thus prepared Lithium substituted ferrite nanomaterials possess pure phase crystal, uniform growth in magnetism with luminescence in visible ranges, which can be useful for multifunctional applications in various areas of science and technology.

Effect of Mn3+ doping on the loss of Li0.37Zn0.26Ti0.12Fe2.37O4 ferrite

In this paper, a series of the gyromagnetic ferrite Li0.43Zn0.26Ti0.12MnxFe2.19−xO4 (x = 0–0.14) samples were prepared with the solid-phase reaction sintering method. The influences of Mn3+ doping on the microscopic morphology, ferromagnetic resonance linewidth, and microwave dielectric loss of LiZnTi ferrite were investigated. Doping in an appropriate amount of Mn3+ will reduce the saturation magnetization of the sample and the magnetocrystalline anisotropy of the ferrite. It also inhibited the generation of Fe2+ and reduced the porosity, to the benefit of keeping the ferromagnetic resonance linewidth (ΔH) of the material and microwave dielectric loss at a low level. The results suggested that when the doping amount of Mn3+ is 0.08, the ferromagnetic resonance linewidth of the material is 27.8 × 103 A m−1, the microwave dielectric loss tangent tanδ ε equals to 0.001, and the B-H hysteresis loop remanence ratio of the sample reaches 0.87, which is a beneficial application in lock-type microwave ferrite devices.

Structural, physical, and magnetic properties of nanocrystalline manganese-substituted lithium ferrite synthesized by sol–gel autocombustion technique

Nanoparticles of spinel ferrite Li0.5–0.5xMnxFe2.5–0.5xO4 (x = 0, 0.25, 0.5, 0.75 and 1) were prepared by sol–gel autocombustion technique. The crystalline phase formation, morphology, cation distribution, and magnetic properties of Li0.5–0.5xMnxFe2.5–0.5xO4 nanoferrite samples were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared (IR) spectroscopy, and vibrating sample magnetometer (VSM). The lattice parameter increases by Mn substitution, while both the crystallite size and Curie temperature (TC) decrease. Values for both the saturation magnetization (Ms) and the coercivity (Hc) were enhanced because both are larger for Mn-substituted samples than those for unsubstituted ones. The addition of Mn2+ ions promotes (Ms) until (x = 0.5) then an appreciable decrease occurs, whereas the coercivity (Hc) increases up to x = 0.25 then it decreases. The role of the substitution with Mn2+ ions in changing all investigated properties of lithium ferrite was explained according to different theories.

Structural properties of magnesium-substituted lithium ferrites

Mg-substituted lithium ferrite Li0.5MgxFe2.5−xO4, where (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0), synthesized through sol–gel auto-combustion method was investigated for their microstructure, cation distribution and magnetic ordering. The results of XRD, SEM and Mossbauer spectroscopy indicate that the Mg2+ concentration plays an important role both in the distribution of cations by spinel lattices and in the change of magnetic fields on 57Fe nuclei in octahedral and tetrahedral environments. By the method of X-ray diffraction structural values such as lattice constant and cation distribution by octahedral and tetrahedral sublattices were determined. Also dependencies of X-ray density, oxygen parameter, ion radii, and length of cation–anion bonds on concentration of doped element (x) were investigated. Rietveld structural refinements using the XRD data were performed on the samples showed that Mg2+ ions replace Fe3+ ions both in tetrahedral and octahedral positions in the ratio of 8:2, while Li+ ions are localized in octahedral positions. Received 57Fe Mossbauer spectra confirmed this structural model.

Structural, Magnetic and Dielectric Properties of Nanocrystalline (M = Li and Mg) Ferrites Synthesized via EDTA/EG Assisted Sol-Gel Method

ABSTRACTIn this study, lithium and magnesium ferrites have been synthesized using EDTA/EG assisted sol-gel method. Based on X-ray diffraction data, it is identified that a spinel-type structure of Li ferrite with space group of P4332 and Mg ferrite with space group of Fd3m has been successfully formed. The estimated value of crystallite size falls within 33-42 nm range. The microstructure of the as-produced powders examined by a field emission scanning electron microscope shows that secondary particles with the mean particle size of 30-170 nm tend to agglomerate severely. Regarding the magnetic properties measured by a vibrating sample magnetometer, Li ferrite, due to higher saturation magnetization than that of Mg ferrite (53.54 versus 23.27 emu.g–1) exhibits superior magnetic properties. In contrast, dielectric properties shows that Mg ferrite gives a much greater dielectric constant at all the measured frequency range.

Synthesis of lithium zinc ceramics with a high saturation magnetization and a low ferromagnetic resonance line-width via two-step sintering strategy using low temperature co-fired ceramic technology

Abstract Lithium zinc ferrite (Li0·435Zn0·26Mn0·06Ti0.1BiyFe2.155-yO4) with a high saturation magnetization (Ms) and a low ferromagnetic resonance line-width ( Δ H ) was successfully synthesized by Low Temperature Co-Fired Ceramic (LTCC) technology using a two-step sintering strategy. In the pre-sintering stage, the optimal amount of active agent (Bi2O3) was added to LiZnMnTi ferrite to reduce reaction activation energy and promote grain growth at low temperature. SEM revealed that active agent effectively reduced critical sintering temperature to 920 °C and promoted grain growth at low temperature. During the final sintering process, various amount of V2O5 additive was added to make up the defect of asymmetrical grain growth caused by imbalances between grain growth and boundary diffusion from the influence of Bi2O3. It not only further promoted grain growth, but also greatly improved grain uniformity, reduced defects and increased material density. Finally, LiZnMnTi ferrite with a high Ms (353 kA/m), a low Δ H (182Oe), and a large average grain size (∼8 μm) was successfully synthesized by adding an optimal amount of V2O5 (0.6 wt%).

Effect of Mo substitution on the structural and soft magnetic properties of Li–Zn ferrites

Spinel ferrites Li0.3Zn0.4MoxFe2.3–xO4 (x = 0.00, 0.01, 0.02, and 0.03) have been prepared by the sol–gel auto-combustion method. The crystal structure, surface morphology, and magnetic properties of the samples have been investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The analysis of XRD data confirms the formation of a cubic Fd-3m phase for the samples with x ≤ 0.02, while a small amount of impurity phases α-Fe2O3 and Li2MoO4 appears in the sample with x = 0.03. The lattice parameter increases at x ≤ 0.02, which indicates that the valence state of Mo ions is mainly trivalent. Both saturation magnetization (Ms) and initial permeability (μi) first decrease and then increase with increasing Mo content. The maximum initial permeability (μi) of 101 is observed at x = 0.03, which is associated with the appearance of the impurity phase α-Fe2O3 with high density. The Curie temperature increases first and then decreases with x increasing. The highest Curie temperature (Tc) of 360 °C is observed at x = 0.02, which may be suitable for higher-temperature soft magnetic materials.

Structural, dielectric and impedance spectroscopic studies of Ni0.5Zn0.5−xLixFe2O4 nanocrystalline ferrites

Nanocrystalline lithium substituted Ni–Zn ferrites with composition Ni[Formula: see text]Zn[Formula: see text]Li[Formula: see text]Fe2O4 ([Formula: see text] = 0.00–0.25 in steps of 0.05) were synthesized by the citrate gel auto-combustion method and were sintered at 1000[Formula: see text]C for 4 h in air atmosphere. The structural, dielectric, impedance spectroscopic and magnetic properties were studied by using X-ray diffraction, impedance analyzer and vibrating sample magnetometer respectively. The X-ray diffraction patterns confirm that all samples exhibit a single phase cubic spinel structure. Suitable cation distribution for all compositions has been proposed by using the X-ray diffraction line intensity calculations and the theoretical lattice parameter for each composition was observed in close agreement with the experimental ones and thereby supporting the proposed distribution. An increase in the saturation magnetization was observed up to [Formula: see text] = 0.10 level of Li[Formula: see text] substitution and thereafter magnetization reduced for higher concentrations to the highest level of Li[Formula: see text] substitution. The dielectric constant and the DC resistivity of Ni–Zn–Li ferrites were noticed to decrease with increase in the Li[Formula: see text] ion concentration. The impedance spectroscopic studies by using the Cole–Cole plots were studied in order to obtain the relaxation time, grain resistance and grain capacitance. AC conductivity initially remained almost independent of frequency for lower frequencies and thereafter for higher frequencies the AC conductivity increased with increase of Lithium concentration.