Phase evolution and room temperature ferroelectric and magnetic properties of Fe-doped BaTiO_3 ceramics

To make the ferroelectric BaTiO3 possess ferromagnetism simultaneously,magnetic Fe was doped into BaTiO3 ceramics at doping levels up to 10%(molar fraction).Both tetragonal and hexagonal phases coexisted in the Fe-doped BaTiO3 ceramics except at 1% doping level.X-ray diffraction analysis indicated that higher doping level of Fe,higher sintering temperature and longer sintering time promoted the formation of hexagonal phases in Fe-doped BaTiO3 ceramics.Ferroelectricity was observed in all samples at room temperature,but it was greatly depressed by Fe doping.Except at doping level of 1%,room-temperature ferromagnetism was observed in the BaTiO3 ceramics.The dependence of the saturation magnetization and coercivities of the Fe-doped BaTiO3 ceramics on doping level was systematically studied.Both the saturation magnetization and magnetic coercivities were found to be dependent on the doping level as well as the fraction of the hexagonal phase in the ceramics.

Meso-macroporous Fe-doped Cu O: Synthesis, characterization, and structurally enhanced adsorption and visible-light photocatalytic activity

The meso-macroporous Fe-doped Cu O was prepared by a simple hydrothermal method combined with post-annealing. The samples were characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), Brunauer-Emmett-Teller N2 adsorption-desorption analyses and UV-vis diffuses reflectance spectroscopy. The Fe-doped Cu O sample shows higher adsorption capacity and photocatalytic activity for xanthate degradation than pure Cu O under visible light irradiation. In addition, the adsorption process is found to fit Langmuir isotherms and pseudo-second-order kinetics. The the first order kinetic Langmuir Hinshelwood model was used to study the reaction kinetics of photocatalytic degradation, and the apparent rate constant( k) was calculated. The value of k for Fe-doped Cu O is 1.5 times that of pure Cu O. The higher photocatalytic activity of Fe-doped Cu O is attributed to higher specific surface area together with stronger visible light absorption.

Synthesis and Room Temperature Ferromagnetism in Fe-Doped CuAlO_2 Semiconductor

The synthesis and characterization of Fe-doped CuA102 semiconductor were reported. The samples were synthesized by a simple and cost effective spin-on technique from solid state reaction of Cu20 and A1203 on sapphire （001） substrate. Appropriate ethyl-cellulose （EC） and terpineol are useful for the formation of Fe-doped CuA102 films. X-ray diffraction （XRD） revealed the growth of pure delafossite CuA102 phase ruled out elemental metallic Fe clusters in all the Fe incorporated CuA102 films. The existence of ferromagnetism at room temperature is evidenced by well-defined hysteresis loops. Specially, the saturation magnetization （Ms） values at room temperature have been monotonously enhanced with the increase of Fe composition from 1% to 5%.

Electron-mediated ferromagnetism in Fe-doped InP:Theory and experiment

We report on the electron-mediated ferromagnetism in Fe-doped InP from both first-principles calculations andexperiments. Theoretically, based on the spin-polarized density functional theory within the Heyd-Scuseria-Ernzerhof （HSE03） approach, we systematically investigate the magnetic properties of Fe-doped InP and predict the existence of electron-mediated ferromagnetism. Experimentally, by diffusing Fe into the n-type InP wafer with thermal annealing at 800 ℃, we observe room-temperature ferromagnetism in InP：Fe, which is in agreement with the theoretical prediction.

Detection of Fe 3d electronic states in the valence band and magnetic properties of Fe-doped ZnO film

Fe-doped ZnO film has been grown by laser molecular beam epitaxy（L-MBE） and structurally characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM）,all of which reveal the high quality of the film.No secondary phase was detected.Resonant photoemission spectroscopy（RPES） with photon energies around the Fe 2p-3d absorption edge is performed to detect the electronic structure in the valence band.A strong resonant effect at a photon energy of 710 eV is observed.Fe3＋ is the only valence state of Fe ions in the film and the Fe 3d electronic states are concentrated at binding energies of about 3.8 eV and 7 eV～8 eV.There are no electronic states related to Fe near the Fermi level.Magnetic measurements reveal a typical superparamagnetic property at room temperature.The absence of electronic states related to Fe near the Fermi level and the high quality of the film,with few defects,provide little support to ferromagnetism.

Fe-doped ZnS film fabricated by electron beam evaporation and its application as saturable absorber for Er:ZBLAN fiber laser

High-quality Fe-doped Zn S films have been fabricated by electron beam evaporation.After the doping,the fabricated films still maintain the preferential crystalline orientation and phase purity of the host Zn S.According to the observation of surface morphology,the root mean-square roughness of the samples increases slightly with the increase of doping content.All of the prepared samples are in cubic zinc blende structure of Zn S.Transmission spectrum confirms a more obvious dip near 3μm with higher dopant concentration and it can be attributed to the typical^(5)E→^(5)T_(2)transition of Fe^(2+).Fe-doped Zn S film is also successfully used for Q-switched Er:ZBLAN fiber laser.

Self-template synthesis of hollow Fe-doped CoP prisms with enhanced oxygen evolution reaction activity

The development of efficient, durable and low cost electrocatalysts is crucial but extremely challenging for the oxygen evolution reaction (OER). Herein, we develop a self-template strategy to synthesize hollow Fe-doped CoP prisms (Fe-CoP) via ion exchange of cobalt acetate hydroxide with [Fe(CN)_(6)]^(3-) and phosphorization-induced transformation of CoFe-PBA (Co/Fe-containing prussian blue analogue) prisms in N2 atmosphere. The obtained Fe-CoP not only inherits the hollow prism-like morphology of CoFe-PBA, but also forms rich mesoporous channel. The Fe-CoP prisms exhibit extraordinary OER performances in 1.0 M KOH, with a low overpotential of 236 mV to deliver a current density of 10 mA cm^(−2) and a low Tafel slope of 32.9 mV dec^(–1). Moreover, the presented electrocatalyst shows good long-term operating durability and activity. The XPS and TEM analysis confirm that Fe-CoP has undergone surface reconstruction in the process of electrocatalytic OER, and the in situ formed oxides and oxyhydroxides are the real active species to boost OER. This work provides a promising pathway to the design and synthesis of efficient and robust electrocatalysts with hierarchical hollow structure for boosting OER.

Photocatalytic Degradation of NOx Under Visible Light Irradiation Using Fe-Doped Titanium Dioxide

In order to utilize visible light in photocatalytic conversion of NOx, Fe atoms were doped in commercially available photocatalytic TiO2 powders by impregnating method. The crystal phase of TiO2 was not changed after calcination process. Analysis by both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that Fe atoms were incorporated in TiO2 as Ti-O-Fe linkages. One significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. The Fe-doped TiO2 powder exhibited photocatalytic activity for the degradation of NOx under visible light irradiation. The sample mixed with 0.2 at% Fe3+and calcined at 600 ℃ showed the best photocatalytic activity.

Fabrication and Characterization of Fe-Doped In2O3 Dilute Magnetic Semiconducting Nanowires

Fe-doped In2O3 dilute magnetic semiconducting nanowires are fabricated on A u-deposited Si substrates by the chemical vapor deposition technique. It is confirmed by energy dispersive x-ray spectroscopy （EDS）, x-ray photoelectron spectroscopy （XPS） and Raman spectroscopy that Fe has been successfully doped into lattices of In2O3 nanowires. The EDS measurements reveal a large amount of oxygen vacancies existing in the Fe-doped In2O3 nanowires. The Fe dopant exists as a mixture of Fe2＋ and Fe3＋, as revealed by the XPS. The origin of room-temperature ferromagnetism in Fe-doped In2O3 nanowires is explained by the bound magnetic polaron model.

Optimization of Conditions for the Photocatalytic Degradation of EDTA in Aqueous Solution with Fe-Doped Titanium Dioxide

The conditions for photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solution with Fe-doped titanium dioxide (TiO2) were optimized. The degradation efficiencies with Fe-doped TiO2 were better, compared with those obtained with bare TiO2 and Pt-doped TiO2. The effect of various experimental factors, such as photocatalytic dosage, temperature, solution pH and light intensity on the photocatalytic degradation of EDTA by Fe-doped TiO2 was investigated. The photocatalytic degradation treatment for the wastewater containing EDTA is simple, easy handling and low cost.

Intrinsic relationship between photoluminescence and electrical characteristics in modulation Fe-doped AlGaN/GaN HEMTs

The photoluminescence（PL） and electrical properties of Al GaN/GaN high electron mobility transistors（HEMTs） with different Fe doping concentrations in the GaN buffer layers were studied. It was found that, at low Fe doping concentrations,the introduction of Fe atoms can result in a downward shift of the Fermi level in the GaN buffer layer, since the Fe atoms substitute Ga and introduce an FeGa^3＋/2＋ acceptor level. This results in a decrease in the yellow luminescence（YL） emission intensity accompanied by the appearance of an infrared（IR） emission, and a decrease in the off-state buffer leakage current（BLC）. However, a further increase in the Fe doping concentration will conversely result in the upward shift of the Fermi level due to the incorporation of O donors under the large flow rate of the Fe source. This results in an increased YL emission intensity accompanied by a decrease in the IR emission intensity, and an increase in the BLC. The intrinsic relationship between the PL and BLC characteristics is expected to provide a simple and effective method to understand the variation of the electrical characteristic in the modulation Fe-doped HEMTs by optical measurements.

Fe-doped Co_(3)O_(4) nanowire strutted 3D pinewood-derived carbon: A highly selective electrocatalyst for ammonia production via nitrate reduction

Nitrate(NO_(3)^(-)),a nitrogen-containing pollutant,is prevalent in aqueous solutions,contributing to a range of environmental and health-related issues.The electrocatalytic reduction of NO_(3)^(-)holds promise as a sustainable approach to both eliminating NO_(3)^(-)and generating valuable ammonia(NH_(3)).Nevertheless,the reduction reaction of NO_(3)^(-)(NO_(3)^(-)RR),involving 8-electron transfer process,is intricate,necessitating highly efficient electrocatalysts to facilitate the conversion of NO_(3)^(-)to NH_(3).In this study,Fe-doped Co_(3)O_(4) nanowire strutted three-dimensional(3D)pinewood-derived carbon(Fe-Co_(3)O_(4)/PC)is proposed as a high-efficiency NO_(3)^(-)RR electrocatalyst for NH_(3) production.Operating within 0.1 M NaOH containing NO_(3)^(-),Fe-Co_(3)O_(4)/PC demonstrates exceptional performance,obtain an impressively large NH_(3) yield of 0.55 mmol·h^(-1)·cm^(-2) and an exceptionally high Faradaic efficiency of 96.5%at-0.5 V,superior to its Co_(3)O_(4)/PC counterpart(0.2 mmol·h^(-1)·cm^(-2),73.3%).Furthermore,the study delves into the reaction mechanism of Fe-Co_(3)O_(4) for NO_(3)^(-)RR through theoretical calculations.

Flower-like Fe-doped NiSe_(2)/C hybrid spheres fabricated by a glucose-intercalation strategy for enhanced sodium storage proper

Nickel diselenide(NiSe_(2)),which has a high theoretical capacity,has attracted considerable attention as a promis-ing anode material for sodium-ion batteries(SIBs).Nevertheless,the intrinsically low conductivity,large volume variation,and significant aggregation of NiSe_(2)during sodiation/desodiation remain significant obstacles to its application.Herein,we report flower-like Fe-doped NiSe_(2)/C hybrid spheres(denoted as Fe-NiSe_(2)/C)fabricated by a glucose intercalation strategy for efficient sodium storage.These Fe-NiSe_(2)/C hybrid spheres are composed of thin porous carbon nanosheets decorated with Fe-NiSe_(2)nanoparticles.In situ introduced carbon nanosheets derived from intercalated glucose accompanied by moderate Fe doping in NiSe2 nanoparticles can provide ac-celerated ion/electron transfer kinetics through fast ion channels in the flower-like architecture and intimately contacted interfaces between NiSe_(2)and carbon nanosheets as well as maintain structural integrity by alleviating volume variation.Consequently,the optimal anode of the Fe-NiSe_(2)/C hybrid spheres delivered a high discharge capacity of 415 mAh g^(-1)at 0.5 A g^(-1),outstanding rate capability(243 mAh g^(-1)at 5 A g^(-1)),and significantly enhanced cycling stability(388 mAh g^(-1)at 1 A g^(-1)over 200 cycles).This work offers an efficient and valu-able strategy for realizing tailored heteroatom doping in transition metal selenides,accompanied by an in situ combination of conductive carbonaceous networks for advanced alkali metal ion batteries.

Achieving ultrahigh electrocatalytic NH_(3) yield rate on Fe-doped Bi_(2)WO_(6) electrocatalyst

NH_(3),derived from electrocatalytic nitrogen reduction reaction(NRR),is promising to satisfy the need of food production and serve as a carbon-free liquid energy carrier in the near future.Yet major challenges remain in enhancing NH_(3) yield rate and conversion efficiency of available electrocatalysts.This work achieved an ultrahigh electrocatalytic NH_(3)yield rate on the_(0.50)Fe-Bi_(2)W0_(6) catalyst by a facile Fe-doped strategy.Up to 289μg·h^(-1)·mg_(cat)^(-1) of NH_(3) formation rate was obtained at-0.75 V vs.RHE,which was reliably quantized by indophenol blue and ^(1)H NMR methods.The impressive result is an order of magnitude higher than that of the reported Fe-and Bi-based catalysts,even more superior than the result of single atom Ru catalyst.The key of the outstanding NRR behaviors on the_(0.50)Fe-Bi_(2)W0_(6) catalyst is the significant hydrogen evolution reaction(HER)suppression and the synergy between Bi and Fe,which can effectively modulate the electron distribution and accelerate the electron transport.This work endows a new insight to further explore the high-performance electrocatalysts toward NRR.

Fe-doped SnO_(2) nanosheet for ambient electrocatalytic nitrogen reduction reaction

Ammonia plays a vital role in the development of modern agriculture and industry.Compared to the conventional Haber–Bosch ammonia synthesis in industry,electrocatalytic nitrogen reduction reaction(NRR)is considered as a promising and environmental friendly strategy to synthesize ammonia.Here,inspired by biological nitrogenase,we designed iron doped tin oxide(Fe-doped SnO_(2))for nitrogen reduction.In this work,iron can optimize the interface electron transfer and improve the poor conductivity of the pure SnO_(2),meanwhile,the synergistic effect between iron and Sn ions improves the catalyst activity.In the electrocatalytic NRR test,Fe-doped SnO_(2) exhibits a NH_(3) yield of 28.45μg·h^(−1)·mgcat^(−1),which is 2.1 times that of pure SnO_(2),and Faradaic efficiency of 6.54%at−0.8 V vs.RHE in 0.1 M Na_(2)SO_(4).It also shows good stability during a 12-h long-term stability test.Density functional theory calculations show that doped Fe atoms in SnO_(2) enhance catalysis performance of some Sn sites by strengthening N–Sn interaction and lowering the energy barrier of the rate-limiting step of NRR.The transient photovoltage test reveals that electrons in the low-frequency region are the key to determining the electron transfer ability of Fe-doped SnO_(2).

Analysis on dye-sensitized solar cells based on Fe-doped TiO_2 by intensity-modulated photocurrent spectroscopy and Mott-Schottky

The pure TiO2 and Fe salts [Fe（C2O4）3,5H2O]-doped TiO2 electrodes were prepared by the hydrothermal method. The pure TiO2 or Fe-doped TiO2 slurry was coated onto the fluorine-doped tin oxide glass substrate by the Doctor Blade method and then sintered at 450 ℃. The Mott-Schottks, plot indicates that the fiat band potential of TiO2 was shifted positively after Fe-doped TiO2. The positive shift of the fiat band potential improves the driving force of injected electrons from the LUMO of the dye to the conduction band of TiO2. This study shows that photovoltaic efficiency increased by 22.9% from 6.07% to 7.46% compared to pure TiO2, and the fill factors increased from 0.53 to 0.63.

Photocatalytic activity of Fe-doped CaTiO_3 under UV–visible light

The photocatalytic degradation of methylene blue（MB） over Fe-doped CaTiO3 under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction（XRD）, scanning electron microscope（SEM） equipped with an energy dispersive spectrometer（EDS） system, Fourier transform infrared spectra（FT-IR）, and UV-visible diffuse reflectance spectroscopy（DRS）. The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO3 in the visible light region. The Fe-doped CaTiO3 exhibited higher photocatalytic activity than CaTiO3 for the degradation of MB.However, the photocatalytic activity of the Fe-doped CaTiO3 was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO3 prepared at500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB（10 ppm）under UV-visible light for 180 min.

Investigations on Fe-doped strontium barium niobate,single phase ferroelectric and magnetodielectric compounds

To understand possible interaction between magnetic and electric order parameters of Fe-doped Sr_(x)Ba_(1-x)Nb_(2)O_(6)(SBN),Fe-doped Sr_(0.5)Ba_(0.5)Nb_(2)O_(6)(SBN50)and Sr_(0.4)Ba_(0.6)Nb_(2)O_(6)(SBN40)are synthesized and investigated.Synthesis has been carried out via ceramic route.The paper reports synthesis,crystal structure,dielectric properties,P-E hysteresis loops,M-H hysteresis loops and magneto-capacitance of the Fe-doped SBN compositions.All the compositions are observed to exhibit a useful value of magnetocapacitance,especially at frequencies less than 10 kHz.

Ferromagnetism in Fe-doped CuO nanopowder

The Fe-doped CuO nanopowder was synthesized by following the standard solid-state reaction method. The structure and magnetic properties of the Fe-doped CuO nanopowder were investigated. X-ray diffraction spec- tra confirmed the monoclinic structure of CuO and no secondary phase was detected, indicating that the Fe ions were incorporated into CuO. The ferromagnetism in Fe-doped CuO was studied and is believed to originate from the interaction between Fe ions and Cu ions via a super-exchange interaction or F-center mediated exchange interaction.

Liquid-phase a-Pinene Isomerization over Fe-doped Sulfated Zirconia Prepared by a Hydrothermal Treatment-assisted Process

A series of Fe-doped （0.5%--3%） sulfated zirconia have been prepared by a hydrothermal treatment-assisted process. Textural and structural characterizations of the as-synthesized materials were performed by means of N2 adsorption, X-ray diffraction, transmission electron microscopy, scanning electron microscopy and thermogravimetric analysis. Temperature-programmed desorption of ammonia was used to determine the acidity of the samples. The effects of Fe-doping on the structure, acidity and catalytic activity of sulfated zirconia for liquid-phase a-pinene isornerization were investigated. The incorporation of small amounts of Fe into sulfated zirconia results in the increase of sulfate content and the number of acid sites, which is responsible for the enhanced activity of Fe-doped catalysts in comparison with the undoped one. Meanwhile, hydrothermal treatment helps to improve the activity of the catalyst.