The fine powders of Mn-Zn ferrites with uniform size were prepared via chemical co- precipitation method. X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, vibrating sample magnetometer （VSM）...The fine powders of Mn-Zn ferrites with uniform size were prepared via chemical co- precipitation method. X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, vibrating sample magnetometer （VSM）, frequency dependence of permeability and metallographical microscope were used to investigate the crystal structure, surface topography and magnetic properties of the powders and the sintering samples. The experimental results demonstrate that the precursor powders have formed a pure phase cubic spinel MnxZn1-xfe2O4 while in the reactor and show definite magnetism, which can solve the difficult issue in washing process effectively. When calcined beneath 450 ℃, the powders have intact crystal form and the crystallite size is less than 20 nm. Comparison tests of sintering temperatures show that 1 300 ℃ is the ideal sintering temperature for Mn-Zn ferrites prepared by using the chemical co-precipitation.展开更多
Mn-Zn ferrites doped with different contents of Sm^（3＋） and Gd^（3＋） ions were prepared by sol-gel auto-combustion method and characterized by Fourier transform infrared spectroscopy（FTIR）, thermogravimetric an...Mn-Zn ferrites doped with different contents of Sm^（3＋） and Gd^（3＋） ions were prepared by sol-gel auto-combustion method and characterized by Fourier transform infrared spectroscopy（FTIR）, thermogravimetric analysis（TG）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and vibrating sample magnetometer（VSM）. When samples were calcined in a relatively low temperature below 1100 °C, secondary phases（α-Fe_2O_3） could be identified. Therefore, in order to acquire pure and better crystallinity, the suitable calcining temperature of powders was selected at 1200 °C. It was also found that all the samples consisting of ferrite phases of typical spinel cubic structure and average crystallite sizes between 31.5 and 38.2 nm were obtained after calcining at 1200 oC for 4 h. The lattice parameters increased almost linearly with increasing Sm content. A dense microstructure was obtained after sintering at 1250 °C for 4 h. Through the analysis of magnetic properties, hysteresis loops for all the samples were narrow with low values of coercivity and retentivity, indicating the paramagnetic nature of these samples. And saturation magnetization Ms strongly depended on the type of additive to reach a maximum of 47.99 emu/g for x=0.015, which showed a great promise for hyperthermia applications.展开更多
The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own in...The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own increases the initial permeability (μi) slightly, but SnO2 with SiO2 and/or CaO decreases the values of μi. However, ferrites with SnO2 additions have reduced power losses. The separate contributions of hysteresis loss and eddy current loss to the total power loss show that SnO2 (with or without SiO2 and/or CaO) doping increases the hysteresis loss slightly, but SnO2 doping alone reduces the eddy current loss significantly (～14%). The additions of SiO2 or CaO further decrease the eddy current loss, and by interaction of SnO2-CaO-SiO2, the eddy current loss is reduced by more than 20%. These magnetic and microstructural effects were discussed in terms of the additive-impurity interaction, the existence of grain boundary phases, and the effective bulk and grain boundary resistivities of the ferrites.展开更多
Effect of the content of dopants in the manganese-zinc ferrites on the low power loss is studied by measuring magnetic properties and observing the grain boundary structures. The Mn0.738Zn0.206Fe2.066O4 composition po...Effect of the content of dopants in the manganese-zinc ferrites on the low power loss is studied by measuring magnetic properties and observing the grain boundary structures. The Mn0.738Zn0.206Fe2.066O4 composition powders were prepared by using conventional ceramic powder processing technique. The microstructure of grain boundary was observed by scanning electron microscope （SEM）. It has been found that power loss is greatly dependent upon the content of the additives.展开更多
The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples...The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples doped with H3BO3 less than 5 × 10^-5 showed that the doping had no significant effect on power loss, initial permeability, fine grain microstructure, and density of Mn-Zn ferrites. With the further increase in H3BO3 doping （up to 1 × 10 ^-4 ）, the microstructure of Mn-Zn ferrites is in the critical state between fine grain and ＂sandwich＂, and the initial permeability and density of Mn-Zn ferrites begin falling quickly; the increased H3BO3 doping also results in deteriorated power loss properties. Thus, the control of the boron content in iron oxide is of utmost importance for the quality of Mn-Zn ferrites in producing process.展开更多
Mn-Zn ferrites （Mn1-xZnxFe2O4） with different compositions were prepared by the coprecipitation method, and the influences of such synthesis conditions as pH value, composition and volume ratio （R） of the mixed so...Mn-Zn ferrites （Mn1-xZnxFe2O4） with different compositions were prepared by the coprecipitation method, and the influences of such synthesis conditions as pH value, composition and volume ratio （R） of the mixed solution and NH4HCO3 solution on their microstructures and magnetic properties were discussed. The samples were characterized by X-ray diffraction （XRD） and magnetization measurement instrument. Lattice parameters and average crystalline size of the synthesized materials were calculated from the corresponding XRD patterns with the related software Jade.5. For samples of different pH values, only one phase was found when pH values were 7.0, 8.0 and 9.0. The sample with pH value of 7.0 exhibited the highest saturation magnetic induction, the lowest coercive force, and crystallized best. For samples of different R values with pH value of 7.0, only one phase was observed in all samples, and the sample with R value of 2.3 exhibited the highest saturation magnetic induction and the lowest coercive force. The composition has mainly afected the magnetic properties, and the saturation magnetic induction increases with the increase of the content of Zn （x）, but decreases when x is beyond 0.6. The trend of coercive force is on the contrary. However, no magnetism is exhibited when the x value is up to 0.8.展开更多
The impact of Cr3+ ion on the magnetic properties of Mn0.50Zn0.50CrxFe2-xO4 (with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) has been studied. Ferrite samples were synthesized by combustion method and sintered at various te...The impact of Cr3+ ion on the magnetic properties of Mn0.50Zn0.50CrxFe2-xO4 (with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) has been studied. Ferrite samples were synthesized by combustion method and sintered at various temperatures (1250°C, 1300°C and 1350°C). The structural properties were investigated by means of X-ray diffraction patterns and indicated that the samples possess single phase cubic spinel structure. The lattice parameter decreases with the increase in Cr3+ content, as the ionic radius of Cr3+ ion is smaller than that of Fe3+. The average grain size (D), bulk density (ρB) and initial permeability (μi’ )decreases with increase in Cr3+ content whereas porosity follows its opposite trend. The ρB was found to increase with increase in Cr3+ content as the sintering temperature (Ts) is increased from 1250°C to 1350°C. The Ts affects the densification, grain growth and (μi’ ) of the samples. The (μi’ ) strongly depends on average grain size, density and intragranular porosity. The B-H loops of the compositions were measured at room temperature. The saturation magnetization (Ms), coercivity (Hc) and hysteresis losses were studied as a function of Cr3+ content. The Ms was found to decrease with the increase of Cr3+ content, which is attributed to the dilution of A-B interaction.展开更多
Pure MnO2, ZnO and Fe2O3 were used to prepare a Mn-Zn Ferrite sample of the nominal composition Mn0.64Zn0.29Fe2.07O4. These oxides were mixed firstly for 1hr, and then were milled for 20 and for 40 hrs. The as-mixed a...Pure MnO2, ZnO and Fe2O3 were used to prepare a Mn-Zn Ferrite sample of the nominal composition Mn0.64Zn0.29Fe2.07O4. These oxides were mixed firstly for 1hr, and then were milled for 20 and for 40 hrs. The as-mixed and the milled powders were examined by XRD and ME spectroscopy. The investigated samples were further mixed with PVA, granulated, cold pressed and sintered at different temperatures (1000, 1300 and 1400 oC) for 2 hrs and were then reinvestigated again. The magnetic properties of all samples before and after sintering were characterized using VSM at a field of 15 k Oe. When the powder oxides were milled for 20 hrs, detectable diffusion reaction was observed where the centers of all XRD peaks (due to Fe2O3 and MnO2) shifted to higher 2? angles, suggesting that Zn2+ cations had diffused through Fe3+ and/or Mn4+ lattices. The observed increase in the width of the XRD peaks can be attributed to the refinement of the powders by milling. Milling of the powder for 40 hrs resulted in the formation of spinel phase of (Zn, Fe), but MnO2 was disappeared probably due to the formation of amorphous structure. Sintering at 1000, 1300, and 1400 oC resulted in the formation of different spinel (Mn-Zn) ferrites. The ME measurements followed the gradual formation the manganese zinc ferrite until complete formation which observed in the sample that milled for 40 hrs followed by sintering at 1300 oC for two hrs. However, it can be concluded that, the processing conditions of such sample represent are the best conditions for obtaining a soft manganese zinc ferrite (single phase).展开更多
Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was p...Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was purified.The effect of the pH on the magnetic properties of Mn-Zn ferrite was investigated by the varying pH of the co-precipitation system.The crystal structure and phases of the samples were characterized by X-ray diffraction and infrared spectrum,respectively.The magnetic measurements were carried out on a vibrating sample magnetometer.The optimal sample was obtained with a saturation magnetization of 55.02 emu/g,a coercivity of 8.20 G and a remanent magnetization of1.71 emu/g when pH is 7.5.展开更多
Nanocrystalline Mn-Zn ferrites （Mno.GZno.4Fe204） with particle size of 12 nm were synthesized hydrotherreally using spent alkaline Zn-Mn batteries, and accompanied by a study of the influencing factors. The nanocrys...Nanocrystalline Mn-Zn ferrites （Mno.GZno.4Fe204） with particle size of 12 nm were synthesized hydrotherreally using spent alkaline Zn-Mn batteries, and accompanied by a study of the influencing factors. The nanocrystals were examined by powder X-ray diffraction （XRD） for crystalline phase identification, and scanning electron microscopy （SEM） for grain morphology. The relationship between concentration of Fe（II）, Mn（II）, and Zn（II） and pH value was obtained through thermodynamic analysis of the Fe（II）-Mn（II）-Zn（II）-NaOH-H2O system. The results showed that all ions were precipitated completely at a pH value of 10-11. The optimal preparation conditions are： co-precipitation pH of 10.5, temperature of 200 ℃ and time of 9 h.展开更多
W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high...W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high-temperature resistance,and excellent chemical stability.However,the poor dielectric loss of magnetic ferrites hampers their utilization,hindering enhancement in their EMW-absorption performance.Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but re-mains challenging.Here,an efficient strategy substituting Ba^(2+)with rare earth La^(3+)in W-type ferrite was proposed for the preparation of novel La-substituted ferrites(Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)).The influences of La^(3+)substitution on ferrites’EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed.La^(3+)efficiently induced lattice defects,enhanced defect-induced polarization,and slightly reduced the ferrites’bandgap,enhancing the dielectric properties of the ferrites.La^(3+)also enhanced the ferromagnetic resonance loss and strengthened magnetic properties.These effects considerably improved the EMW-absorption perform-ance of Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)compared with pure W-type ferrites.When x=0.2,the best EMW-absorption performance was achieved with a minimum reflection loss of-55.6 dB and effective absorption bandwidth(EAB)of 3.44 GHz.展开更多
Copper-zinc-nickel(Cu-Zn-Ni)ferrite nanoparticles are used for wastewater treatment technology.However,low degradation efficiency and stability are two main issues that make them unsuitable for actual production needs...Copper-zinc-nickel(Cu-Zn-Ni)ferrite nanoparticles are used for wastewater treatment technology.However,low degradation efficiency and stability are two main issues that make them unsuitable for actual production needs.In this paper,the citrate-nitrate auto-combustion method was applied for the formation of Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(x)Fe_(2-x)O_(4);(0≤x≤0.1;step 0.02)(CZNL)nanoferrites.Although the substitution process entails the replacement of a small ion with a larger one,the lattice constant and crystallite size does not exhibit a consistent incremental pattern.This behavior is justified and discussed.The size of all the CZNL ferrite nanoparticles is in the range of 8-12 nm,and the lattice constant is in the range of 8.6230 to 8.4865 nm.The morphological analysis conducted using field emission-scanning electron microscopy(FE-SEM)reveals that the CZNL exhibits agglomerated spherical morphology.The energy dispersive X-ray spectrameter(EDAX)analysis was employed to confirm the elemental composition of CZNL nanoferrites.Since the process entails the substitution of Fe^(3+)magnetic ions with nonmagnetic ions La^(3+),the magnetic parameters of CZNL nanoferrites show a general decreasing trend as predicted.At 20 K,saturation magnetization Ms shows an overall drop in its values from 59.302 emu/g at x=0.0-41.295 emu/g at x=0.1,the smallest value of 37.87 emu/g is recorded at x=0.06.the highest coercivity(H_(c)=125.9 Oe)and remanence(M_(r)=13.32 emu/g)are recorded for x=0.08 and x=0.04 nanoferrite,respectvely.The band gap of all the CZNL nanoferrites was determined using the Kubelka-Munk function and Tauc plot for direct permitted transitions.La doping modifies the band gap(within 1.86-1.75 eV),increases light absorption,induces efficient e/h separation and charge migration to Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(x)Fe_(2-x)O_(4)surfaces.The nanoferrite Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)achieves a degradation efficiency of 97.3%for methylene blue(MB)dye removal after just 60 min.After five recycling processes,the nanocatalyst Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)is degraded by 95.83%,resulting in a negligible1.51%decrease in photocatalytic activity efficiency.The new Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)has exceptional photocatalytic activity and remarkable stability,making it a promising candidate for applications in wastewater treatment.展开更多
The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications ...The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications in the mid to low-frequency range of gigahertz.In this study,we prepared Z-type Ba_(3)Co_(1.6−x)Zn_(x)Cu_(0.4)Fe_(24)O_(41)hexaferrites using the sol-gel auto-combustion method.By changing the ratio of Co and Zn ions,the magnetocrystalline anisotropy of ferrite is further ma-nipulated,resulting in significant changes in their magnetic resonance frequency and intensity.Ba_(3)Zn_(1.6)Cu_(0.4)Fe_(24)O_(41)with high-frequency resonance achieved the lowest reflectivity of−72.18 dB at 15.56 GHz,while Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)with stronger loss obtained the widest bandwidth of 4.93 GHz(6.14-11.07).Additionally,we investigated surface wave suppression properties previously overlooked.Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)can achieve a larger attenuation at low frequency under low thickness,which has an excellent effect on reducing backscattering.This work provides a useful reference for the preparation and application of high-performance magnetic-loss materials.展开更多
Nanoferrites of the CoMn_(x)Fe_(2-x)O_(4) series(x=0.00,0.05,0.10,0.15,0.20)were synthesized in this study using the sol-gel auto-combustion approach.The lattice constants were computed within the range of 8.312-8.406...Nanoferrites of the CoMn_(x)Fe_(2-x)O_(4) series(x=0.00,0.05,0.10,0.15,0.20)were synthesized in this study using the sol-gel auto-combustion approach.The lattice constants were computed within the range of 8.312-8.406Å,while crystallite sizes were estimated to range between 55.20 and 31.40 nm using the Scherrer method.The different functional groups were found to correlate with various ab-sorption bands using Fourier transform infrared(FTIR)spectroscopy.Five active modes were identified by Raman spectroscopy,reveal-ing vibration modes of O2-ions at tetrahedral and octahedral locations.The ferromagnetic hysteresis loop was observed in all the synthes-ized samples,which can be explained by Neel’s model.The results showed that AC conductivity decreased with increasing Mn^(2+)content at the Fe^(2+)site,while the dielectric constant and dielectric loss increased with increasing frequency.Furthermore,the saturation magnetiz-ation(Ms),remnant magnetization(M_(r)),and coercivity(H_(c))all showed declining trends with the increase in Mn^(2+)doping.Finally,the CoMn_(0.20)Fe_(1.8)O_(4) samples showed Ms and M_(r) values ranging from 73.12 to 66.84 emu/g and from 37.77 to 51.89 emu/g,respectively,while Hc values ranged from 1939 to 1312 Oe,after which coercivity increased.Thus,the CoMn_(0.20)Fe_(1.8)O_(4) sample can be considered a prom-ising candidate for magnetic applications.展开更多
Rare earth metal ferrites-based heterojunctions have garnered significant attention in recent years due to their exceptional photocatalytic properties and potential applications in water treatment and energy conversio...Rare earth metal ferrites-based heterojunctions have garnered significant attention in recent years due to their exceptional photocatalytic properties and potential applications in water treatment and energy conversion.The incorporation of rare earth metal ferrites into heterojunction photocatalytic systems enhances light absorption,charge separation and photocatalytic efficiency.This review comprehensively discusses some common types of rare earth metal ferrites such as LaFeO_(3),GdFeO_(3),SmFeO_(3),PrFeO_(3)and CeFeO_(3)and their properties as photocatalysts.The photocatalytic pollutants removal and energy conversion mechanisms are discussed in detail and various types of heterojunctions reported in literature based on rare earth metal ferrites and their synthetic routes are also explored.The recent key findings and advances in the heterojunctions based on these rare earth metal ferrites for the pollutants removal and energy conversion applications are summarized.Despite notable progress in enhancing photocatalytic efficiency and stability,several challenges remain.Current research highlights improvements in material synthesis and performance,but issues such as high production costs,scalable synthesis and limited long-term stability persist.Future directions should focus on exploring uncharted applications,novel material combinations and enhancing the practical implementation of these heterojunctions to fully exploit their potential in environmental and energy technologies.展开更多
The effect of Zn2+ ions on the microstructure and electrical properties of Mn1-xZnxFe2O4 (0.0 ≤ x ≤ 0.5 in steps of 0.1) through a solid state reaction has been investigated. The structural properties have been inve...The effect of Zn2+ ions on the microstructure and electrical properties of Mn1-xZnxFe2O4 (0.0 ≤ x ≤ 0.5 in steps of 0.1) through a solid state reaction has been investigated. The structural properties have been investigated using X-ray diffraction (XRD) technique. The XRD analysis confirms that all samples are in a single-phase cubic spinel structure. The experimental lattice parameter (aexp) was decreased with increasing Zn2+ ions substitution due to the smaller ionic radius of zinc content. The crystallite size (t) of samples was estimated by Scherrer’s formula and found in the range (90 - 115 nm). Dc electrical resistivity and Seebeck voltage coefficients were measured as a function of temperature using the two probe methods. The temperature variation of resistivity exhibits two breaks, each break referring to a change in the activation energy. The Curie temperature estimated from dc resistivity measurement decreases with increasing Zn2+ ions. Seebeck voltage coefficient measurements reveal n-type conduction for all samples.展开更多
To develop advanced electromagnetic interference(EMI)shielding materials,Mn-Mo ferrites doped with Ce were investigated for their electric,dielectric,and magnetic properties.Using Density Functional Theory(DFT)calcula...To develop advanced electromagnetic interference(EMI)shielding materials,Mn-Mo ferrites doped with Ce were investigated for their electric,dielectric,and magnetic properties.Using Density Functional Theory(DFT)calculation,the effect of doping different elements was evaluated in ferrite structures to optimize the performance of these ferrites.The calculated results revealed that the Mn-Mo ferrites which combined with Ce significantly lowered the bandgap and increased the total density of states(TDOS),leading to improved electrical conductivity.Additionally,the dielectric constant(ε')dielectric loss(ε'')and AC conductivity were found to be highest in the Mn-Mo-Ce-doped ferrites,contributing to superior EMI shielding effectiveness(SE),particularly in the low-frequency range.Mn-Mo-Ce doped ferrite was synthesized using auto-combustion method and evaluated for the EMI SE.The experimental and DFT calculated EMI SE both are close to 55 dB.This computational and experimental analysis,supported by structural and electronic localization function(ELF)mapping,underscores the potential of Mn-Mo-Ce-doped ferrites as highly efficient materials for EMI shielding in advanced electronic applications.展开更多
In this study,Cu_(0.25)Ni_(0.5)Zn_(0.25)Fe_(2-x)Nd_(x)O_(4)(0.000≤x≤0.100,andΔx=0.025)spinel ferrites were synthesized using the auto-combustion method to investigate the influence of neodymium(Nd^(3+))substitution...In this study,Cu_(0.25)Ni_(0.5)Zn_(0.25)Fe_(2-x)Nd_(x)O_(4)(0.000≤x≤0.100,andΔx=0.025)spinel ferrites were synthesized using the auto-combustion method to investigate the influence of neodymium(Nd^(3+))substitution on their structural,optical,dielectric,and magnetic properties.X-ray diffraction result confirms the formation of a face-centered cubic spinel structure,with the average crystallite size decreasing from 39 to 15 nm as Nd^(3+)concentration increases.Fourier transform infrared spectroscopy reveals characteristic absorption bands,affirming the spinel structure.Dielectric measurements over a broad frequency range show a higher dielectric constant and lower dielectric loss,indicating potential suitability for energy-efficient electronic applications.Magnetic analysis using a vibrating sample magnetometer demonstrates soft magnetic behavior,with saturation magnetization decreasing from82.69 to 66.80 emu/g and a tunable ratio(0.0221-0.0068)of remnant magnetization to saturation magnetization depending on Nd^(3+)content.In situ ultrasonic studies provides phase transition temperature(Curie temperature,T_(c))values ranging from 516 to 489 K,highlighting thermal stability and magnetic phase transition behavior.Furthermore,reflection loss measurements in the X-band frequency range(8-12 GHz)confirm the excellent electromagnetic interference shielding and radar absorption capabilities of Cu_(0.25)Ni_(0.5)Zn_(0.25)Fe_(2-x)Nd_(x)O_(4)spinel ferrites.These findings underscore the potential of Nd^(3+)-doped Cu-Ni-Zn spinel ferrites for advanced technological applications,including electronic devices,thermal sensors,and electromagnetic wave absorbers.展开更多
Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity ...Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.展开更多
Spinel ferrite Ni_(0.08)Mn_(0.90)Zn_(0.02)Fe_(2)O_(4)was prepared by a conventional ceramic process followed by sintering at three different temperatures(1050°C,1100°C and 1150°C).X-ray diffraction(XRD)...Spinel ferrite Ni_(0.08)Mn_(0.90)Zn_(0.02)Fe_(2)O_(4)was prepared by a conventional ceramic process followed by sintering at three different temperatures(1050°C,1100°C and 1150°C).X-ray diffraction(XRD)investigations stated the single-phase cubic spinel structure and the FTIR spectra revealed two prominent bands within the wavenumber region from 600 cm^(−1)to 400 cm^(−1).Surface morphol-ogy showed highly crystalline grain development with sizes ranging from 0.27μm to 0.88μm.The magnetic hysteresis curve at ambient temperature revealed a significant effect of sintering temperature on both coercivity(Hc)and saturation magnetization(Ms).Temperature caused a decrease in DC electrical resistivity,while the electron transport increased,suggesting the semicon-ducting nature of all samples and that they well followed the Arrhenius law from which their activation energies were determined.The values of Curie temperature(Tc)and activation energy were influenced by the sintering temperature.Frequency-dependent dielectric behavior(100 Hz-1 MHz)was also analyzed,which may be interpreted by the Maxwell-Wagner-type polarization.The UV-vis-NIR reflectance curve was analyzed to calculate the bandgap of ferrites,which showed a decreasing trend with increasing sintering temperature.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51162019 and 51462019)
文摘The fine powders of Mn-Zn ferrites with uniform size were prepared via chemical co- precipitation method. X-ray diffraction analysis （XRD）, scanning electron microscopy （SEM）, vibrating sample magnetometer （VSM）, frequency dependence of permeability and metallographical microscope were used to investigate the crystal structure, surface topography and magnetic properties of the powders and the sintering samples. The experimental results demonstrate that the precursor powders have formed a pure phase cubic spinel MnxZn1-xfe2O4 while in the reactor and show definite magnetism, which can solve the difficult issue in washing process effectively. When calcined beneath 450 ℃, the powders have intact crystal form and the crystallite size is less than 20 nm. Comparison tests of sintering temperatures show that 1 300 ℃ is the ideal sintering temperature for Mn-Zn ferrites prepared by using the chemical co-precipitation.
基金Project supported by the National Natural Science Foundation of China(51102073)the Natural Science Foundation of Education Department of Anhui Province of China(KJ2015A232,KJ2015B1105906)+3 种基金the Natural Science Foundation of Anhui Province of China(1308085QB35)the research fund of State Key Laboratory of Structural Chemistry(20110012)Anhui Province Outstanding Young Teachers Visit Abroad Training Projects(gxfxZD2016220)the Outstanding Young Talent Project in Colleges and Universities of Anhui Province
文摘Mn-Zn ferrites doped with different contents of Sm^（3＋） and Gd^（3＋） ions were prepared by sol-gel auto-combustion method and characterized by Fourier transform infrared spectroscopy（FTIR）, thermogravimetric analysis（TG）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and vibrating sample magnetometer（VSM）. When samples were calcined in a relatively low temperature below 1100 °C, secondary phases（α-Fe_2O_3） could be identified. Therefore, in order to acquire pure and better crystallinity, the suitable calcining temperature of powders was selected at 1200 °C. It was also found that all the samples consisting of ferrite phases of typical spinel cubic structure and average crystallite sizes between 31.5 and 38.2 nm were obtained after calcining at 1200 oC for 4 h. The lattice parameters increased almost linearly with increasing Sm content. A dense microstructure was obtained after sintering at 1250 °C for 4 h. Through the analysis of magnetic properties, hysteresis loops for all the samples were narrow with low values of coercivity and retentivity, indicating the paramagnetic nature of these samples. And saturation magnetization Ms strongly depended on the type of additive to reach a maximum of 47.99 emu/g for x=0.015, which showed a great promise for hyperthermia applications.
文摘The effects of additive SnO2 (0.4wt.%), with and without SiO2 (0.02wt.%) and/or CaO (0.04wt.%), on the microstructure and magnetic properties of Mn-Zn ferrites were reported. The results reveal that SnO2 on its own increases the initial permeability (μi) slightly, but SnO2 with SiO2 and/or CaO decreases the values of μi. However, ferrites with SnO2 additions have reduced power losses. The separate contributions of hysteresis loss and eddy current loss to the total power loss show that SnO2 (with or without SiO2 and/or CaO) doping increases the hysteresis loss slightly, but SnO2 doping alone reduces the eddy current loss significantly (～14%). The additions of SiO2 or CaO further decrease the eddy current loss, and by interaction of SnO2-CaO-SiO2, the eddy current loss is reduced by more than 20%. These magnetic and microstructural effects were discussed in terms of the additive-impurity interaction, the existence of grain boundary phases, and the effective bulk and grain boundary resistivities of the ferrites.
基金Project supported by National High-Technology Research and De-velopment Program(Grant No .2001AA3250380)
文摘Effect of the content of dopants in the manganese-zinc ferrites on the low power loss is studied by measuring magnetic properties and observing the grain boundary structures. The Mn0.738Zn0.206Fe2.066O4 composition powders were prepared by using conventional ceramic powder processing technique. The microstructure of grain boundary was observed by scanning electron microscope （SEM）. It has been found that power loss is greatly dependent upon the content of the additives.
文摘The ferrites of PC30 （Mn-Zn ferrites） were prepared by using a dry processing route. The effect of Mn-Zn ferrites doped with H3BO3 was investigated on the basis of microstructure analysis. The results of the samples doped with H3BO3 less than 5 × 10^-5 showed that the doping had no significant effect on power loss, initial permeability, fine grain microstructure, and density of Mn-Zn ferrites. With the further increase in H3BO3 doping （up to 1 × 10 ^-4 ）, the microstructure of Mn-Zn ferrites is in the critical state between fine grain and ＂sandwich＂, and the initial permeability and density of Mn-Zn ferrites begin falling quickly; the increased H3BO3 doping also results in deteriorated power loss properties. Thus, the control of the boron content in iron oxide is of utmost importance for the quality of Mn-Zn ferrites in producing process.
基金Funded by the Basic Key Project in Shanghai City (06JC14033)the Key Discipline Construction Fund in Shanghai City (P1304)
文摘Mn-Zn ferrites （Mn1-xZnxFe2O4） with different compositions were prepared by the coprecipitation method, and the influences of such synthesis conditions as pH value, composition and volume ratio （R） of the mixed solution and NH4HCO3 solution on their microstructures and magnetic properties were discussed. The samples were characterized by X-ray diffraction （XRD） and magnetization measurement instrument. Lattice parameters and average crystalline size of the synthesized materials were calculated from the corresponding XRD patterns with the related software Jade.5. For samples of different pH values, only one phase was found when pH values were 7.0, 8.0 and 9.0. The sample with pH value of 7.0 exhibited the highest saturation magnetic induction, the lowest coercive force, and crystallized best. For samples of different R values with pH value of 7.0, only one phase was observed in all samples, and the sample with R value of 2.3 exhibited the highest saturation magnetic induction and the lowest coercive force. The composition has mainly afected the magnetic properties, and the saturation magnetic induction increases with the increase of the content of Zn （x）, but decreases when x is beyond 0.6. The trend of coercive force is on the contrary. However, no magnetism is exhibited when the x value is up to 0.8.
文摘The impact of Cr3+ ion on the magnetic properties of Mn0.50Zn0.50CrxFe2-xO4 (with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) has been studied. Ferrite samples were synthesized by combustion method and sintered at various temperatures (1250°C, 1300°C and 1350°C). The structural properties were investigated by means of X-ray diffraction patterns and indicated that the samples possess single phase cubic spinel structure. The lattice parameter decreases with the increase in Cr3+ content, as the ionic radius of Cr3+ ion is smaller than that of Fe3+. The average grain size (D), bulk density (ρB) and initial permeability (μi’ )decreases with increase in Cr3+ content whereas porosity follows its opposite trend. The ρB was found to increase with increase in Cr3+ content as the sintering temperature (Ts) is increased from 1250°C to 1350°C. The Ts affects the densification, grain growth and (μi’ ) of the samples. The (μi’ ) strongly depends on average grain size, density and intragranular porosity. The B-H loops of the compositions were measured at room temperature. The saturation magnetization (Ms), coercivity (Hc) and hysteresis losses were studied as a function of Cr3+ content. The Ms was found to decrease with the increase of Cr3+ content, which is attributed to the dilution of A-B interaction.
文摘Pure MnO2, ZnO and Fe2O3 were used to prepare a Mn-Zn Ferrite sample of the nominal composition Mn0.64Zn0.29Fe2.07O4. These oxides were mixed firstly for 1hr, and then were milled for 20 and for 40 hrs. The as-mixed and the milled powders were examined by XRD and ME spectroscopy. The investigated samples were further mixed with PVA, granulated, cold pressed and sintered at different temperatures (1000, 1300 and 1400 oC) for 2 hrs and were then reinvestigated again. The magnetic properties of all samples before and after sintering were characterized using VSM at a field of 15 k Oe. When the powder oxides were milled for 20 hrs, detectable diffusion reaction was observed where the centers of all XRD peaks (due to Fe2O3 and MnO2) shifted to higher 2? angles, suggesting that Zn2+ cations had diffused through Fe3+ and/or Mn4+ lattices. The observed increase in the width of the XRD peaks can be attributed to the refinement of the powders by milling. Milling of the powder for 40 hrs resulted in the formation of spinel phase of (Zn, Fe), but MnO2 was disappeared probably due to the formation of amorphous structure. Sintering at 1000, 1300, and 1400 oC resulted in the formation of different spinel (Mn-Zn) ferrites. The ME measurements followed the gradual formation the manganese zinc ferrite until complete formation which observed in the sample that milled for 40 hrs followed by sintering at 1300 oC for two hrs. However, it can be concluded that, the processing conditions of such sample represent are the best conditions for obtaining a soft manganese zinc ferrite (single phase).
基金financed by the Bureau of Land Resources and Housing Management of Chongqing(Scientific & Technologic Program in 2011)the Science and Technology Bureau of Hengyang(Scientific & Technologic Program in 2013)the State Administration of Work Safety(Scientific & Technologic Program in 2013)
文摘Mn-Zn ferrite powders were produced from low-grade manganese ore(LMO) via the chemical coprecipitation method combined with the ceramic method,after the LMO was leached in sulfuric acid and the obtained solution was purified.The effect of the pH on the magnetic properties of Mn-Zn ferrite was investigated by the varying pH of the co-precipitation system.The crystal structure and phases of the samples were characterized by X-ray diffraction and infrared spectrum,respectively.The magnetic measurements were carried out on a vibrating sample magnetometer.The optimal sample was obtained with a saturation magnetization of 55.02 emu/g,a coercivity of 8.20 G and a remanent magnetization of1.71 emu/g when pH is 7.5.
文摘Nanocrystalline Mn-Zn ferrites （Mno.GZno.4Fe204） with particle size of 12 nm were synthesized hydrotherreally using spent alkaline Zn-Mn batteries, and accompanied by a study of the influencing factors. The nanocrystals were examined by powder X-ray diffraction （XRD） for crystalline phase identification, and scanning electron microscopy （SEM） for grain morphology. The relationship between concentration of Fe（II）, Mn（II）, and Zn（II） and pH value was obtained through thermodynamic analysis of the Fe（II）-Mn（II）-Zn（II）-NaOH-H2O system. The results showed that all ions were precipitated completely at a pH value of 10-11. The optimal preparation conditions are： co-precipitation pH of 10.5, temperature of 200 ℃ and time of 9 h.
基金financially supported by the National Key R&D Program of China(No.2021YFB3502500)the Natur-al Science Foundation of Shandong Province,China(No.2022HYYQ-014)+5 种基金the“20 Clauses about Colleges and Uni-versities(new)”(Independent Training of Innovation Team)Program of Jinan,China(No.2021GXRC036)the Provin-cial Key Research and Development Program of Shandong,China(No.2021ZLGX01)the National Natural Science Foundation of China(No.22375115)the Joint Laboratory project of Electromagnetic Structure Technology(No.637-2022-70-F-037)the Discipline Construction Expenditure for Distinguished Young Scholars of Shandong University,China(No.31370089963141)the Qilu Young Scholar Program of Shandong University,China(No.31370082163127).
文摘W-type barium-nickel ferrite(BaNi_(2)Fe_(16)O_(27))is a highly promising material for electromagnetic wave(EMW)absorption be-cause of its magnetic loss capability for EMW,low cost,large-scale production potential,high-temperature resistance,and excellent chemical stability.However,the poor dielectric loss of magnetic ferrites hampers their utilization,hindering enhancement in their EMW-absorption performance.Developing efficient strategies that improve the EMW-absorption performance of ferrite is highly desired but re-mains challenging.Here,an efficient strategy substituting Ba^(2+)with rare earth La^(3+)in W-type ferrite was proposed for the preparation of novel La-substituted ferrites(Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)).The influences of La^(3+)substitution on ferrites’EMW-absorption performance and the dissipative mechanism toward EMW were systematically explored and discussed.La^(3+)efficiently induced lattice defects,enhanced defect-induced polarization,and slightly reduced the ferrites’bandgap,enhancing the dielectric properties of the ferrites.La^(3+)also enhanced the ferromagnetic resonance loss and strengthened magnetic properties.These effects considerably improved the EMW-absorption perform-ance of Ba_(1-x)LaxNi_(2)Fe_(15.4)O_(27)compared with pure W-type ferrites.When x=0.2,the best EMW-absorption performance was achieved with a minimum reflection loss of-55.6 dB and effective absorption bandwidth(EAB)of 3.44 GHz.
文摘Copper-zinc-nickel(Cu-Zn-Ni)ferrite nanoparticles are used for wastewater treatment technology.However,low degradation efficiency and stability are two main issues that make them unsuitable for actual production needs.In this paper,the citrate-nitrate auto-combustion method was applied for the formation of Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(x)Fe_(2-x)O_(4);(0≤x≤0.1;step 0.02)(CZNL)nanoferrites.Although the substitution process entails the replacement of a small ion with a larger one,the lattice constant and crystallite size does not exhibit a consistent incremental pattern.This behavior is justified and discussed.The size of all the CZNL ferrite nanoparticles is in the range of 8-12 nm,and the lattice constant is in the range of 8.6230 to 8.4865 nm.The morphological analysis conducted using field emission-scanning electron microscopy(FE-SEM)reveals that the CZNL exhibits agglomerated spherical morphology.The energy dispersive X-ray spectrameter(EDAX)analysis was employed to confirm the elemental composition of CZNL nanoferrites.Since the process entails the substitution of Fe^(3+)magnetic ions with nonmagnetic ions La^(3+),the magnetic parameters of CZNL nanoferrites show a general decreasing trend as predicted.At 20 K,saturation magnetization Ms shows an overall drop in its values from 59.302 emu/g at x=0.0-41.295 emu/g at x=0.1,the smallest value of 37.87 emu/g is recorded at x=0.06.the highest coercivity(H_(c)=125.9 Oe)and remanence(M_(r)=13.32 emu/g)are recorded for x=0.08 and x=0.04 nanoferrite,respectvely.The band gap of all the CZNL nanoferrites was determined using the Kubelka-Munk function and Tauc plot for direct permitted transitions.La doping modifies the band gap(within 1.86-1.75 eV),increases light absorption,induces efficient e/h separation and charge migration to Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(x)Fe_(2-x)O_(4)surfaces.The nanoferrite Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)achieves a degradation efficiency of 97.3%for methylene blue(MB)dye removal after just 60 min.After five recycling processes,the nanocatalyst Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)is degraded by 95.83%,resulting in a negligible1.51%decrease in photocatalytic activity efficiency.The new Cu_(0.5)Zn_(0.25)Ni_(0.25)La_(0.06)Fe_(1.94)O_(4)has exceptional photocatalytic activity and remarkable stability,making it a promising candidate for applications in wastewater treatment.
基金supported by the National Natural Science Foundation of China(No.62371222)the Defense Industrial Technology Development Program(No.JCKY2023605C002)thePriority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(No.ZHD202305).
文摘The intrinsic high magnetocrystalline anisotropy equivalent field can help the hexaferrites break through Snoek’s limit and increase the resonance frequency.This is advantageous for microwave absorption applications in the mid to low-frequency range of gigahertz.In this study,we prepared Z-type Ba_(3)Co_(1.6−x)Zn_(x)Cu_(0.4)Fe_(24)O_(41)hexaferrites using the sol-gel auto-combustion method.By changing the ratio of Co and Zn ions,the magnetocrystalline anisotropy of ferrite is further ma-nipulated,resulting in significant changes in their magnetic resonance frequency and intensity.Ba_(3)Zn_(1.6)Cu_(0.4)Fe_(24)O_(41)with high-frequency resonance achieved the lowest reflectivity of−72.18 dB at 15.56 GHz,while Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)with stronger loss obtained the widest bandwidth of 4.93 GHz(6.14-11.07).Additionally,we investigated surface wave suppression properties previously overlooked.Ba_(3)Co_(1.5)Zn_(0.1)Cu_(0.4)Fe_(24)O_(41)can achieve a larger attenuation at low frequency under low thickness,which has an excellent effect on reducing backscattering.This work provides a useful reference for the preparation and application of high-performance magnetic-loss materials.
文摘Nanoferrites of the CoMn_(x)Fe_(2-x)O_(4) series(x=0.00,0.05,0.10,0.15,0.20)were synthesized in this study using the sol-gel auto-combustion approach.The lattice constants were computed within the range of 8.312-8.406Å,while crystallite sizes were estimated to range between 55.20 and 31.40 nm using the Scherrer method.The different functional groups were found to correlate with various ab-sorption bands using Fourier transform infrared(FTIR)spectroscopy.Five active modes were identified by Raman spectroscopy,reveal-ing vibration modes of O2-ions at tetrahedral and octahedral locations.The ferromagnetic hysteresis loop was observed in all the synthes-ized samples,which can be explained by Neel’s model.The results showed that AC conductivity decreased with increasing Mn^(2+)content at the Fe^(2+)site,while the dielectric constant and dielectric loss increased with increasing frequency.Furthermore,the saturation magnetiz-ation(Ms),remnant magnetization(M_(r)),and coercivity(H_(c))all showed declining trends with the increase in Mn^(2+)doping.Finally,the CoMn_(0.20)Fe_(1.8)O_(4) samples showed Ms and M_(r) values ranging from 73.12 to 66.84 emu/g and from 37.77 to 51.89 emu/g,respectively,while Hc values ranged from 1939 to 1312 Oe,after which coercivity increased.Thus,the CoMn_(0.20)Fe_(1.8)O_(4) sample can be considered a prom-ising candidate for magnetic applications.
文摘Rare earth metal ferrites-based heterojunctions have garnered significant attention in recent years due to their exceptional photocatalytic properties and potential applications in water treatment and energy conversion.The incorporation of rare earth metal ferrites into heterojunction photocatalytic systems enhances light absorption,charge separation and photocatalytic efficiency.This review comprehensively discusses some common types of rare earth metal ferrites such as LaFeO_(3),GdFeO_(3),SmFeO_(3),PrFeO_(3)and CeFeO_(3)and their properties as photocatalysts.The photocatalytic pollutants removal and energy conversion mechanisms are discussed in detail and various types of heterojunctions reported in literature based on rare earth metal ferrites and their synthetic routes are also explored.The recent key findings and advances in the heterojunctions based on these rare earth metal ferrites for the pollutants removal and energy conversion applications are summarized.Despite notable progress in enhancing photocatalytic efficiency and stability,several challenges remain.Current research highlights improvements in material synthesis and performance,but issues such as high production costs,scalable synthesis and limited long-term stability persist.Future directions should focus on exploring uncharted applications,novel material combinations and enhancing the practical implementation of these heterojunctions to fully exploit their potential in environmental and energy technologies.
文摘The effect of Zn2+ ions on the microstructure and electrical properties of Mn1-xZnxFe2O4 (0.0 ≤ x ≤ 0.5 in steps of 0.1) through a solid state reaction has been investigated. The structural properties have been investigated using X-ray diffraction (XRD) technique. The XRD analysis confirms that all samples are in a single-phase cubic spinel structure. The experimental lattice parameter (aexp) was decreased with increasing Zn2+ ions substitution due to the smaller ionic radius of zinc content. The crystallite size (t) of samples was estimated by Scherrer’s formula and found in the range (90 - 115 nm). Dc electrical resistivity and Seebeck voltage coefficients were measured as a function of temperature using the two probe methods. The temperature variation of resistivity exhibits two breaks, each break referring to a change in the activation energy. The Curie temperature estimated from dc resistivity measurement decreases with increasing Zn2+ ions. Seebeck voltage coefficient measurements reveal n-type conduction for all samples.
基金supported by the National Natural Science Foundation of China,China(51872231,51672221)the Key Industrial Chain Project of Shaanxi Province,China(2018ZDCXL-GY-08–07).
文摘To develop advanced electromagnetic interference(EMI)shielding materials,Mn-Mo ferrites doped with Ce were investigated for their electric,dielectric,and magnetic properties.Using Density Functional Theory(DFT)calculation,the effect of doping different elements was evaluated in ferrite structures to optimize the performance of these ferrites.The calculated results revealed that the Mn-Mo ferrites which combined with Ce significantly lowered the bandgap and increased the total density of states(TDOS),leading to improved electrical conductivity.Additionally,the dielectric constant(ε')dielectric loss(ε'')and AC conductivity were found to be highest in the Mn-Mo-Ce-doped ferrites,contributing to superior EMI shielding effectiveness(SE),particularly in the low-frequency range.Mn-Mo-Ce doped ferrite was synthesized using auto-combustion method and evaluated for the EMI SE.The experimental and DFT calculated EMI SE both are close to 55 dB.This computational and experimental analysis,supported by structural and electronic localization function(ELF)mapping,underscores the potential of Mn-Mo-Ce-doped ferrites as highly efficient materials for EMI shielding in advanced electronic applications.
基金Princess Nourah bint Abdulrahman University Researchers Supporting Project(No.PNURSP2025R479)。
文摘In this study,Cu_(0.25)Ni_(0.5)Zn_(0.25)Fe_(2-x)Nd_(x)O_(4)(0.000≤x≤0.100,andΔx=0.025)spinel ferrites were synthesized using the auto-combustion method to investigate the influence of neodymium(Nd^(3+))substitution on their structural,optical,dielectric,and magnetic properties.X-ray diffraction result confirms the formation of a face-centered cubic spinel structure,with the average crystallite size decreasing from 39 to 15 nm as Nd^(3+)concentration increases.Fourier transform infrared spectroscopy reveals characteristic absorption bands,affirming the spinel structure.Dielectric measurements over a broad frequency range show a higher dielectric constant and lower dielectric loss,indicating potential suitability for energy-efficient electronic applications.Magnetic analysis using a vibrating sample magnetometer demonstrates soft magnetic behavior,with saturation magnetization decreasing from82.69 to 66.80 emu/g and a tunable ratio(0.0221-0.0068)of remnant magnetization to saturation magnetization depending on Nd^(3+)content.In situ ultrasonic studies provides phase transition temperature(Curie temperature,T_(c))values ranging from 516 to 489 K,highlighting thermal stability and magnetic phase transition behavior.Furthermore,reflection loss measurements in the X-band frequency range(8-12 GHz)confirm the excellent electromagnetic interference shielding and radar absorption capabilities of Cu_(0.25)Ni_(0.5)Zn_(0.25)Fe_(2-x)Nd_(x)O_(4)spinel ferrites.These findings underscore the potential of Nd^(3+)-doped Cu-Ni-Zn spinel ferrites for advanced technological applications,including electronic devices,thermal sensors,and electromagnetic wave absorbers.
基金supported by the Ondokuz Mayis University Project Number PYO.MUH.1901.21.001。
文摘Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.
文摘Spinel ferrite Ni_(0.08)Mn_(0.90)Zn_(0.02)Fe_(2)O_(4)was prepared by a conventional ceramic process followed by sintering at three different temperatures(1050°C,1100°C and 1150°C).X-ray diffraction(XRD)investigations stated the single-phase cubic spinel structure and the FTIR spectra revealed two prominent bands within the wavenumber region from 600 cm^(−1)to 400 cm^(−1).Surface morphol-ogy showed highly crystalline grain development with sizes ranging from 0.27μm to 0.88μm.The magnetic hysteresis curve at ambient temperature revealed a significant effect of sintering temperature on both coercivity(Hc)and saturation magnetization(Ms).Temperature caused a decrease in DC electrical resistivity,while the electron transport increased,suggesting the semicon-ducting nature of all samples and that they well followed the Arrhenius law from which their activation energies were determined.The values of Curie temperature(Tc)and activation energy were influenced by the sintering temperature.Frequency-dependent dielectric behavior(100 Hz-1 MHz)was also analyzed,which may be interpreted by the Maxwell-Wagner-type polarization.The UV-vis-NIR reflectance curve was analyzed to calculate the bandgap of ferrites,which showed a decreasing trend with increasing sintering temperature.
