Fe Sb Research Articles

An experimental study on the nuclear radiation attenuation properties of Fe–Sb–Pb doped concretes prepared with different cement types

An experimental study on the nuclear radiation attenuation properties of Fe–Sb–Pb doped concretes prepared with different cement types

Heavily Fe-doped quaternary-alloy ferromagnetic semiconductor (In,Ga,Fe)Sb

We study epitaxial growth and physical properties of heavily Fe-doped quaternary-alloy ferromagnetic semiconductor (In0.84−x ,Ga x ,Fe0.16)Sb thin films (Ga content x = 2%–10%, Fe content fixed at 16%). The (In0.84−x ,Ga x ,Fe0.16)Sb films have a zinc-blende-type crystal structure without any other second phase, and all the samples exhibit intrinsic ferromagnetism with high Curie temperature (>300 K). The carrier type of the (In0.84−x ,Ga x ,Fe0.16)Sb films is found to change by varying x, and a carrier-type phase diagram of (In,Ga,Fe)Sb is presented. These results suggest that (In,Ga,Fe)Sb is a promising material for semiconductor spintronic devices, such as ferromagnetic p-n junctions, operating at RT.

Computational investigation of high Curie temperature in a new N‐type ferromagnetic diluted magnetic semiconductors, especially iron‐doped on GaSb

AbstractDiluted magnetic semiconductors have become a research area in the past few years due to the importance of new technology, spintronics devices, and green technology to withstand rising global temperatures. Both n‐type and p‐type diluted magnetic semiconductors are used in pairs for perfect performance, especially for p‐n junction diodes, the p‐d Zener model, GMR, and TMR spintronics devices. The main challenge for some researchers is to find a ferromagnetic diluted magnetic semiconductor with a Curie temperature greater than room temperature for both n‐type and p‐type ferromagnetic diluted semiconductors, but this study has solved this problem. In the present study, the ferromagnetic properties of an n‐type gallium iron antimonide diluted semiconductor have been studied using the Hamiltonian model without applying an external magnetic field, electric field, or chemical potential. We have formulated a Hamiltonian model in the system, considering the application of the green formalism function and the transformation of Holstein–Primakaff. The Curie temperature, dispersion, number of magnons, reduced magnetization, and specific heat capacity of ferromagnetic magnons of the n‐type (Ga, Fe)Sb formula are formulated. The Curie temperature versus concentration graph is plotted, and the specific heat capacity and magnetization versus temperature graphs are plotted. In this study, a surprising situation is that the Curie temperature of n‐type diluted magnetic semiconductor is investigated above room temperature, which is 330.4 K. The ferromagnetic properties of appear up to 330.4 K, which is able to play a major role in spintronic and next‐generation green nanotechnology devices.

Observation of large spin-polarized Fermi surface of a magnetically proximitized semiconductor quantum well

The magnetic proximity effect (MPE) attracts much attention as a promising way for introducing ferromagnetism into a nonmagnetic electron-transport channel. Although the range of MPE is generally limited to the interface, it is extended to several tens of nm in high-quality semiconductor bilayers consisting of a nonmagnetic quantum well (QW) and an underlying ferromagnetic semiconductor (FMS) layer. To elucidate the mechanism of this long-range MPE, it is essential to observe the magnetically proximitized electronic structure of the nonmagnetic semiconductor. Here, by investigating the Shubnikov - de Haas oscillations in nonmagnetic n-type InAs QW / FMS (Ga,Fe)Sb bilayers, we successfully observe the spin-polarized Fermi surface of the InAs QW. The spontaneous spin-splitting energy in the conduction band of the InAs QW reaches 18 meV when applying a negative gate voltage. This large and gate-tunable spin-polarized Fermi surface of a magnetically proximitized InAs QW provides an ideal platform for novel spintronic and topological devices.

Enhanced magnetic anisotropy and high hole mobility in magnetic semiconductor Ga1-x-y Fe x Ni y Sb

(Ga,Fe)Sb is a promising magnetic semiconductor (MS) for spintronic applications because its Curie temperature (T C) is above 300 K when the Fe concentration is higher than 20%. However, the anisotropy constant K u of (Ga,Fe)Sb is below 7.6 × 103 erg/cm3 when Fe concentration is lower than 30%, which is one order of magnitude lower than that of (Ga,Mn)As. To address this issue, we grew Ga1-x-y Fe x Ni y Sb films with almost the same x (≈24%) and different y to characterize their magnetic and electrical transport properties. We found that the magnetic anisotropy of Ga0.76-y Fe0.24Ni y Sb can be enhanced by increasing y, in which K u is negligible at y = 1.7% but increases to 3.8 × 105 erg/cm3 at y = 6.1% (T C = 354 K). In addition, the hole mobility (µ) of Ga1-x-y Fe x Ni y Sb reaches 31.3 cm2/(V∙s) at x = 23.7%, y = 1.7% (T C = 319 K), which is much higher than the mobility of Ga1-x Fe x Sb at x = 25.2% (µ = 6.2 cm2/(V∙s)). Our results provide useful information for enhancing the magnetic anisotropy and hole mobility of (Ga,Fe)Sb by using Ni co-doping.

Ferromagnetism induced by hybridization of Fe 3d orbitals with ligand InSb bands in the n -type ferromagnetic semiconductor (In,Fe)Sb

Fe-doped III-V ferromagnetic semiconductor (FMS) (In,Fe)Sb is a promising material for spintronic device applications because of the n-type carrier conduction and the ferromagnetism with high Curie temperature (TC > 300 K). To clarify the mechanism of the high-TC ferromagnetism, we have investigated the electronic structure and magnetic properties of an (In,Fe)Sb thin film by performing x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at the Fe L2,3 edges. The magnetic-field dependence of the XMCD spectra reveals that there are ferromagnetic-like Fe and paramagnetic-like Fe components in the (In,Fe)Sb thin film. The XAS and XMCD spectra of the ferromagnetic-like and paramagnetic-like Fe components resemble those of other Fe-doped FMSs and extrinsic oxides, respectively. The finite value of the ratio between the orbital and spin magnetic moments estimated by applying the XMCD sum rules indicates that the valence state of the Fe ions substituting for the In sites in (In,Fe)Sb is not purely ionic Fe3+, but intermediate between Fe3+ and Fe2+. The qualitative correspondence between the magnetic-field dependence of the visible-light magnetic circular dichroism intensity and that of the XMCD intensity demonstrates that the Zeeman splitting of the InSb band is proportional to the net magnetization of the doped Fe. These results suggest that the ferromagnetism of (In,Fe)Sb originates from the Fe 3d orbitals hybridized with the host InSb bands.

Fe segregation as a tool to enhance electrical conductivity of grain boundaries in Ti(Co,Fe)Sb half Heusler thermoelectrics

Fe segregation as a tool to enhance electrical conductivity of grain boundaries in Ti(Co,Fe)Sb half Heusler thermoelectrics

Speciation and mobility of arsenic and antimony in soils and mining wastes from an abandoned Sb–Au mining area

Gold mining activities have long been recognized as one of the most important local sources of arsenic (As) and antimony (Sb). While the environmental impact of As is documented in the literature from many mining regions worldwide, still little data is available concerning the environmental chemistry and associations of Sb. Here, we used bulk analyses, selective extractions, X-ray diffraction, electron microprobe, and Raman microspectrometry to determine and compare the distribution, speciation, and mobility of As and Sb in three historical mining wastes and two soil profiles at the Krásná Hora-Milešov and Příčovy Sb–Au ore districts (Czech Republic). The mining wastes were slightly alkaline, with both high and variable concentrations of As (318–1360 mg/kg) and Sb (214–8740 mg/kg). The naturally developed soils were acidic to neutral and enriched in As (up to 208 mg/kg) as well as in Sb (up to 255 mg/kg), with the highest concentrations in the arable topsoil (≤40 cm). In the mining wastes, the primary ore minerals (arsenopyrite, pyrite, and stibnite) have been substantially oxidized and replaced by secondary As and Sb mineral phases such as Fe (hydr)oxides, Ca–Fe–Sb (hydr)oxides, as well as the less common Ca–Sb (hydr)oxides and Ca–Fe arsenates. The primary sulfide minerals were absent in the soils, and both As and Sb were particularly bound to crystalline Fe (hydr)oxides (goethite and hematite) and clay minerals (especially true for Sb). The leaching of As and Sb from all the samples with water was pH-dependent and relatively low, as less than 2.1% of the total As and Sb contents in the samples had been released. Water-extractable concentrations were usually below 30 μg/L for As and 450 μg/L for Sb, except for an alkaline and As- and Sb-rich mining wastes, which released up to 1500 μg/L of As and 5400 μg/L of Sb. Interaction of agricultural soils with low PO43− indicated that As was more likely mobilized by the addition of low PO43− (0.1 mM) than Sb was. Although the water extraction data mostly documented the higher mobility of Sb compared to As, the addition of low PO43− into agricultural soils strongly increases As mobility. Based on the results of this study, leaching of As and Sb from mining wastes by rainwater can contribute to the dispersion of these metalloids and a potential hazard for the surrounding environments.

Room-temperature spin injection from a ferromagnetic semiconductor

Spin injection using ferromagnetic semiconductors at room temperature is a building block for the realization of spin-functional semiconductor devices. Nevertheless, this has been very challenging due to the lack of reliable room-temperature ferromagnetism in well-known group IV and III-V based semiconductors. Here, we demonstrate room-temperature spin injection by using spin pumping in a BiSb/(Ga,Fe)Sb heterostructure, where (Ga,Fe)Sb is a ferromagnetic semiconductor (FMS) with high Curie temperature (TC) and BiSb is a topological insulator (TI). Despite the very small magnetization of (Ga,Fe)Sb at room temperature (45 emu/cc), we detected spin injection from (Ga,Fe)Sb by utilizing the large inverse spin Hall effect (ISHE) in BiSb. Our study provides the first demonstration of spin injection at room temperature from a FMS.

Giant gate-controlled odd-parity magnetoresistance in one-dimensional channels with a magnetic proximity effect

According to Onsager’s principle, electrical resistance R of general conductors behaves as an even function of external magnetic field B. Only in special circumstances, which involve time reversal symmetry (TRS) broken by ferromagnetism, the odd component of R against B is observed. This unusual phenomenon, called odd-parity magnetoresistance (OMR), was hitherto subtle (< 2%) and hard to control by external means. Here, we report a giant OMR as large as 27% in edge transport channels of an InAs quantum well, which is magnetized by a proximity effect from an underlying ferromagnetic semiconductor (Ga,Fe)Sb layer. Combining experimental results and theoretical analysis using the linearized Boltzmann’s equation, we found that simultaneous breaking of both the TRS by the magnetic proximity effect (MPE) and spatial inversion symmetry (SIS) in the one-dimensional (1D) InAs edge channels is the origin of this giant OMR. We also demonstrated the ability to turn on and off the OMR using electrical gating of either TRS or SIS in the edge channels. These findings provide a deep insight into the 1D semiconducting system with a strong magnetic coupling.

Band structure engineering in Fe–Sb based lanthanide filled p-type skutterudites RFe4Sb12 (R = Nd, Sm) to enhance the Seebeck coefficient and thermoelectric figure of merit

Structural, thermodynamic, electronic, and thermoelectric properties of two pure ternary skutterudites, NdFe4Sb12 and SmFe4Sb12, and their doped counterparts, Sm-doped NdFe4Sb12 and Nd-doped SmFe4Sb12, have been investigated using full potential linearized augmented plane wave formalism under density functional theory. In doped systems, the central lanthanide atom was replaced by a different filler atom. Thermodynamic parameters indicate that all the materials are stable, sufficiently hard, and will have a high melting point. Band profiles reveal their semimetallic nature with a pseudo-bandgap above the Fermi level and crossing of the Fermi level of one or more bands. The facts that the trivalent fillers do not provide enough electrons required for charge compensation of Fe4Sb12 and the Fermi levels are well inside the valence band also predict their p-type nature. The splitting of DOS of the f-electrons of the filler atoms into both spin channels implies their ferromagnetic nature. The Sm-doped system exhibits the highest magnetic moment because of the much lower anti-ferromagnetic moment of Fe. Between the pure compounds, the lighter filler atom-based NdFe4Sb12 exhibits a higher ZT value because of the higher population density of states and higher concentration of degenerate flatbands. Contrary to recent predictions, both the doped systems show higher ZT than the pure ones. However, the presence of larger pseudo-bandgaps in both spin channels and two peaks just above the Fermi level in the majority spin channel in the lighter Nd-doped system results in the enhanced Seebeck coefficient, reduced thermal conductivity, and the maximum ZT value of 0.90 at 1000 K.

Gate-controlled proximity magnetoresistance in In1−xGaxAs/(Ga,Fe)Sb bilayer heterostructures

The magnetic proximity effect (MPE), ferromagnetic coupling at the interface of magnetically dissimilar layers, attracts much attention as a promising pathway for introducing ferromagnetism into a high-mobility non-magnetic conducting channel. Recently, our group found giant proximity magnetoresistance (PMR), which is caused by MPE at an interface between a non-magnetic semiconductor InAs quantum well (QW) layer and a ferromagnetic semiconductor (Ga,Fe)Sb layer. The MPE in the non-magnetic semiconductor can be modulated by applying a gate voltage and controlling the penetration of the electron wavefunction in the InAs QW into the neighboring insulating ferromagnetic (Ga,Fe)Sb layer. However, optimal conditions to obtain strong MPE at the InAs/(Ga,Fe)Sb interface have not been clarified. In this paper, we systematically investigate the PMR properties of In1-xGaxAs (x = 0%, 5%, 7.5%, and 10%) / (Ga,Fe)Sb bilayer semiconductor heterostructures under a wide range of gate voltage. The inclusion of Ga alters the electronic structures of the InAs thin film, in particular changing the effective mass and the QW potential of electron carriers. Our experimental results and theoretical analysis of the PMR in these In1-xGaxAs/(Ga,Fe)Sb heterostructures show that the MPE depends not only on the degree of penetration of the electron wavefunction into (Ga,Fe)Sb but also on the electron density. These findings help us to unveil the microscopic mechanism of MPE in semiconductor-based non-magnetic/ferromagnetic heterojunctions.

Development of magnetism in Fe-doped magnetic semiconductors: Resonant photoemission and x-ray magnetic circular dichroism studies of (Ga,Fe)As

Fe-doped III-V ferromagnetic semiconductors (FMSs) such as (In,Fe)As, (Ga,Fe)Sb, (In,Fe)Sb, and (Al,Fe)Sb are promising materials for spintronic device applications because of the availability of both $\mathrm{n}$- and $\mathrm{p}$-type materials and the high Curie temperatures. On the other hand, (Ga,Fe)As, which has the same zinc-blende crystal structure as the Fe-doped III-V FMSs, shows paramagnetism. The origin of the different magnetic properties in the Fe-doped III-V semiconductors remains to be elucidated. To address this issue, we use resonant photoemission spectroscopy (RPES) and x-ray magnetic circular dichroism (XMCD) to investigate the electronic and magnetic properties of the Fe ions in a paramagnetic $({\mathrm{Ga}}_{0.95},{\mathrm{Fe}}_{0.05})\mathrm{As}$ thin film. The observed Fe $2p\text{\ensuremath{-}}3d$ RPES spectra show that the Fe $3d$ states are similar to those of ferromagnetic (Ga,Fe)Sb. The estimated Fermi level is located in the middle of the band gap in (Ga,Fe)As. The Fe ${L}_{2,3}$ XMCD spectra of $({\mathrm{Ga}}_{0.95},{\mathrm{Fe}}_{0.05})\mathrm{As}$ show preedge structures, which are not observed in the Fe-doped FMSs, indicating that the minority-spin (\ensuremath{\downarrow}) ${e}_{\ensuremath{\downarrow}}$ states are vacant in $({\mathrm{Ga}}_{0.95},{\mathrm{Fe}}_{0.05})\mathrm{As}$. The XMCD results suggest that the carrier-induced ferromagnetic interaction in $({\mathrm{Ga}}_{0.95},{\mathrm{Fe}}_{0.05})\mathrm{As}$ is short ranged and weaker than that in the Fe-doped FMSs. The experimental findings suggest that the electron occupancy of the ${e}_{\ensuremath{\downarrow}}$ states contributes to the appearance of ferromagnetism in the Fe-doped III-V semiconductors, for $\mathrm{p}$-type as well as $\mathrm{n}$-type compounds.

Self-healing action of Bi in high-performance Sb–Bi–Sn positive electrodes for liquid metal batteries

Li||Sb–Bi–Sn liquid metal batteries (LMBs) have comprehensive advantages of a high energy density, excellent rate capability, low material costs, and high cycle performance. However, the corrosion of the positive electrode to the current collector at high temperatures cannot be neglected over the long term. Here, we investigate the corrosion behavior of SS304 in two types of Sb–Bi–Sn alloys under static and cell cycling conditions. Interestingly, we find that the cell performance of Li||Sb–Bi–Sn LMBs are not affected by corrosion between the positive electrode and stainless-steel current collector. The corrosion products and their participation in the cell reaction process are determined using ex situ analyses and electrochemical measurements. Bi not only inhibits the dissolution of SS304 in Sb–Bi–Sn alloy but also spontaneously promotes the decomposition of Fe–Sb and Fe–Cr–Sb corrosion products during lithiation, releasing the active component Sb, and Sb–Bi–Sn alloy is recovered. Encouragingly, even in the event of corrosion, the cell capacity, efficiency, and cycle stability remain almost unaffected due to this self-healing action of Bi. This study represents a new direction toward inhibiting the corrosion of positive electrode and stabilizing cell performance for practical application and commercialization by alloying.

Coagulation Behavior of Antimony Oxyanions in Water: Influence of pH, Inorganic and Organic Matter on the Physicochemical Characteristics of Iron Precipitates.

The presence of inorganic and organic substances may alter the physicochemical properties of iron (Fe) salt precipitates, thereby stabilizing the antimony (Sb) oxyanions in potable water during the chemical treatment process. Therefore, the present study aimed to examine the surface characteristics, size of Fe flocs and coagulation performance of Sb oxyanions under different aqueous matrices. The results showed that surface properties of Fe flocs significantly varies with pH in both Sb(III, V) suspensions, thereby increasing the mobility of Sb(V) ions in alkaline conditions. The negligible change in surface characteristics of Fe flocs was observed in pure water and Sb(III, V) suspension at pH 7. The key role of Van der Waals forces of attraction as well as hydration force in the aggregation of early formed flocs were found, with greater agglomeration capability at higher more ferric chloride dosage. The higher Sb(V) loading decreased the size of Fe flocs and reversed the surface charge of precipitates, resulting in a significant reduction in Sb(V) removal efficiency. The competitive inhibition effect on Sb(III, V) removal was noticed in the presence of phosphate anions, owing to lowering of ζ-potential values towards more negative trajectory. The presence of hydrophobic organic matter (humic acid) significantly altered the surface characteristics of Fe flocs, thereby affecting the coagulation behavior of Sb in water as compared to the hydrophilic (salicylic acid). Overall, the findings of this research may provide a new insight into the variation in physicochemical characteristics of Fe flocs and Sb removal behavior in the presence of inorganic and organic compounds during the drinking water treatment process.

Spin transport in fully ferromagnetic p–n junctions

We systematically investigate the spin-dependent transport properties of fully ferromagnetic (Ga,Fe)Sb/GaSb/(In,Fe)Sb and (Ga,Fe)Sb/(In,Fe)As p–n junctions grown by low-temperature molecular beam epitaxy. The (Ga,Fe)Sb/GaSb/(In,Fe)Sb p–n junctions show high Curie temperature (170–310 K) and rectifying characteristics. The polarity and magnitude of magnetoresistance of the (Ga,Fe)Sb/GaSb/(In,Fe)Sb junctions strongly depend on the GaSb spacer thickness (t). Large positive magnetoresistance (MR, 58%) and negative MR (−1.6%) were observed at 3.7 K for the samples with t = 2 and 4 nm, respectively. When the n-type (In,Fe)Sb layer was replaced by the n-type (In,Fe)As, giant MR over 500% was observed, which can be explained by spin-valve and spin-splitting effects. Our results shed light on rich spin-transport physics observed in fully ferromagnetic p–n junctions.

Metal-arene reduced Fe–Sb nanoparticles as a highly efficient catalyst for nitrophenol reduction

High catalytic efficiency of first time synthesised Fe–Sb alloyed NPs via sodium naphthalenide driven reduction approach.

Tri-α-PbO2-Type Fe–Sb Tungstate by Topotactic Ion Exchange of LiSbWO6

Tri-α-PbO₂-Type Fe–Sb Tungstate by Topotactic Ion Exchange of LiSbWO₆

Strain-tuned magnetic properties in (Ga,Fe)Sb: First-principles study* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11764032 and 11665018).

In view of the importance of enhancing ferromagnetic (FM) coupling in dilute magnetic semiconductors (DMSs), the effects of strain on the electronic structures and magnetic properties of (Ga,Fe)Sb were examined by a first-principles study. The results of the investigation indicate that FeGa substitution takes place in the low-spin state (LSS) with a total magnetic moment of 1μ B in the strain range of –3% to 0.5%, which transitions to the high-spin state (HSS) with a total magnetic moment of 5μ B as the strain changes from 0.6% to 3%. We attribute the changes in the amount and distribution of the total moment to the influence of the crystal field under different strains. The FM coupling is strongest under a strain of about 0.5%, but gradually becomes weaker with increasing compressive and tensile strains. The magnetic coupling mechanism is discussed in detail. Our results highlight the important contribution of strain to magnetic moment and FM interaction intensity, and present an interesting avenue for the future design of high Curie temperature (T C) materials in the (Ga,Fe)Sb system.

Redox Behavior of Chelate Complexes Based on 8-Oxyquinoline Promising in OLED Display Technology

The electrochemical behavior of 8-oxyquinoline and chelate complexes based on it (Sn (Oxin)Cl3, Ge (Oxin)Cl3, Ti (Oxin)Cl3, W(Oxin)2Cl4, Fe (Oxin)Br, Sb (Oxin)Cl2, Sb (Oxin)Cl4, Sn (Oxin)2Cl2, Ti (Oxin)2Cl2 have been studied by cyclic voltammetry in aprotic solvents in a three-electrode system on platinum and glass-graphite disk electrodes. It has been shown that in the case of metal oxyquinolinates, the ligand is 8-oxyquinoline reducing in two one-electron diffusion waves. The first wave is observed at less negative potentials than the first quinoline one, while the second waves have almost the same potentials. The first wave is related to the OH- proton discharge. The complexes under study are electrolytically oxidizable. A single two-electron peak is observed in the cyclic voltammogram in the anodic region for the Ti (Oxin)Cl3 chelate complex. This is probably associated with two irreversible sequential or parallel stages with close oxidation potentials. By analogy to the processes considered for 8-oxyquinoline, the rupture of the oxygen-metal bond is observed at the first stage. The resulting radical cation is unstable and decomposes into a radical and a cation with a positive charge in the titanium atom. Electrolytic oxidation of complexes Fe (Oxin)Br, Sb (Oxin)Cl2, Sb (Oxin)Cl4, and Sn (Oxin)2Cl2 is similar to that of Ti (Oxin)Cl3.