Mn Sb Research Articles

Magnetic properties of Mn-doped InSb nanowires from first principles

Room-temperature ferromagnetism (RTFM) has been achieved in Mn-doped InSb nanowires (NWs) through experiment. However, the underlying cause of RTFM remains unclear. In this paper, using first-principles calculations, the distribution of Mn ions and magnetic properties of Mn-doped wurtzite and zinc blend InSb NWs have been investigated. Our results indicate that wurtzite (In,Mn)Sb NWs can exhibit superior ferromagnetic behavior compared to zinc blend (In,Mn)Sb NWs. The distribution of Mn ions and magnetic properties in the (In,Mn)Sb NWs is influenced by their size, surface passivation and crystal structure. Furthermore, the ferromagnetic coupling is short-range in passivated (In,Mn)Sb NWs, and as the size of the NW decreases, the Mn-3d level becomes a deep acceptor in the band gap, resulting in an enhancement of ferromagnetism.

Magnetic Field-Induced Martensitic Phase Transition in Cr-Substituted Ni–Mn–Sb + B Shape Memory Alloys

Magnetic Field-Induced Martensitic Phase Transition in Cr-Substituted Ni–Mn–Sb + B Shape Memory Alloys

The effect of Mn on structural, magnetic and magnetoresistance properties of Ni–Mn–Sb Heusler melt spun ribbons under extreme conditions

Ni50 − x Mn37 + x Sb13 (NMS (x = 4–6)) melt-spun Heusler ribbon was fabricated by employing the arc melting technique. Also, the electrical, structural, and magnetic characteristics of melt-spun alloy ribbons with chemically increased Mn (a decrease in Ni concentration) content are also being investigated. Further, it has been noticed that, the Curie temperatures of the austenitic (T C A) phase and the martensitic phase transition temperature (T M) are both shifted toward higher temperatures, by increasing the amount of Mn under 500 Oe (0.05 T) of applied magnetic fields. The discontinuity of field cooling (FC) and zero field cooling (ZFC) curves reveals the irreversibility of magnetization caused by inhomogeneous magnetic anisotropy lower the exchange bias (EB) (blocking bias) temperature. Furthermore, the disappearance of exchange bias (EB) in ribbon alloys with increasing temperature is supported by the fact that coercivity (H C) gradually increases with temperature and increases at 40 K, and then decreases with temperature. Additionally, a −ΔS Max of −5.21 Jkg−1·K−1 for a ribbon with x = 6 is acquired at 312 K with a 50 kOe (5 T) change in the applied magnetic field. Increases in Mn content result in −ΔS M values in NMS alloy ribbons of −4.3, −4.7, and −5.2 Jkg−1·K−1 and the same trend is observed in negative magneto-resistance ((−MR) (%)) values of −9%, −11%, and −14% for x = 4–6, respectively. Here, the super zone boundary that is close to the Fermi surface is responsible for the change in −MR.

Effect of a high-gradient magnetic field on grain refinement of a hypoeutectic Mn–Sb alloy during directional solidification

The obvious grain refinement of the primary MnSb phase has been observed in the Mn–89.7 wt% Sb alloy directionally solidified under a high-gradient magnetic field. With the application of a high-gradient magnetic field, the morphology of the primary MnSb phase transformed from developed dendritic-like to equiaxed-like, and the grain size decreased by approximately 93%. Refinement of the primary MnSb phase can be attributed to the constituent supercooling in front of the solidification interface, which promoted nucleation of the primary MnSb phase. The constituent supercooling can be linked to the enrichment of the Mn solute induced by the magnetic force and the Lorentz force that drove Mn solute migration and suppressed convection.

Glass trade through the Adriatic Sea: preliminary report of an ongoing project

A repertoire of 1357 glass samples from Italy, Croatia, Slovenia and Serbia was used to investigate glass trade in the Adriatic Sea. The achieved overview begins in the 1st century and, after a peak of occurrences between the 4th and the 7th century, continues until the 16th with a decreasing number of pieces of evidence.Between the 1st and the 3rd century, Levantine (Roman Mn) and Egyptian (Roman Sb) products coexist in percentages that can be considered comparable at the current state of studies. The end of the 3rd and the beginning of the 4th century mark a substantial decrease in Levantine imports. Indeed, Jalame-type glass first and Apollonia-type glass later appear to supply a small slice of the market. Egyptian products, on the contrary, continue to arrive in abundance. The HIMTa and the Foy Série 2.1 glass represent the most widespread products in the Adriatic area for about three centuries. Conversely, the Foy Série 3.2 experiences flowering in northern Italy, Slovenia and Serbia, while it shows limited diffusion in southern Italy, as well as in Tyrrhenian Italy, Sicily or other areas of the Mediterranean basin such as Spain. Based on this observation, it thus seems reliable to exclude Foy Série 3.2 glass from the basket of products typically marketed in the Adriatic Sea (i.e. Levantine products and Egyptian products of types HIMTa-b and Foy 2.1). In this case, a Balkan route may appear possible because it covers the territories where the most significant diffusion of this glass has been observed and is well connected to northern Italy through the Danube and Sava rivers. In southern Italy, the need for more data on the oldest productions prevents a reliable evaluation of Roman Mn and Roman Sb glass imports and highlights a line of research to be pursued in the immediate future.

Colossal negative magnetoresistance in spin glass Na(Zn,Mn)Sb

We report the study of magnetic and transport properties of polycrystalline and single crystal Na(Zn,Mn)Sb, a new member of “111” type of diluted magnetic materials. The material crystallizes into Cu2Sb-type structure which is isostructural to “111” type Fe-based superconductors. With suitable carrier and spin doping, the Na(Zn,Mn)Sb establishes spin-glass ordering with freezing temperature (T f ) below 15 K. Despite lack of long-range ferromagnetic ordering, Na(Zn,Mn)Sb single crystal still shows sizeable anomalous Hall effect below T f . Carrier concentration determined by Hall effect measurements is over 1019 cm–3. More significantly, we observe colossal negative magnetoresistance (MR ≡ [ρ(H) − ρ(0)]/ρ(0)) of –94% in the single crystal sample.

Induced transformation of antimony trioxide by Mn(II) oxidation and their co-transformed mechanism

Antimony (Sb) is a toxic and carcinogenic element that often enters soil in the form of antimony trioxide (Sb2O3) and coexists with manganese (Mn) in weakly alkaline conditions. Mn oxides such as birnessite have been found to promote the oxidative dissolution of Sb2O3, but few researches concerned the co-transformations of Sb2O3 and Mn(II) in environment. This study investigated the mutual effect of abiotic oxidation of Mn(II) and the coupled oxidative dissolution of Sb2O3. The influencing factors, such as Mn(II) concentrations, pH and oxygen were also discussed. Furthermore, their co-transformed mechanism was also explored based on the analysis of Mn(II) oxidation products with or without Sb2O3 using XRD, SEM and XPS. The results showed that the oxidative dissolution of Sb2O3 was enhanced under higher pH and higher Mn(II) loadings. With a lower Mn(II) concentration such as 0.01 mmol/L Mn(II) at pH 9.0, the improved dissolution of Sb2O3 was attributed to the generation of dissolved intermediate Mn(III) species with strong oxidation capacity. However, under higher Mn(II) concentrations, both amorphous Mn(III) oxides and intermediate Mn(III) species were responsible for promoting the oxidative dissolution of Sb2O3. Most released Sb (∼72%) was immobilized by Mn oxides and Sb(V) was dominant in the adsorbed and dissolved total Sb. Meanwhile, the presence of Sb2O3 not only inhibited the removal of Mn(II) by reducing Mn(III) to Mn(II) but also affected the final products of Mn oxides. For example, amorphous Mn oxides were formed instead of crystalline Mn(III) oxides, such as MnOOH. Furthermore, rhodochrosite (MnCO3) was formed with the high Mn(II)/Sb2O3 ratio, but without being observed in the low Mn(II)/Sb2O3 ratio. The results of study could help provide more understanding about the fate of Sb in the environment and the redox transformation of Mn.

Phase Transitions, Structure Evolution, and Thermoelectric Properties Based on A2MnSb2 (A = Ca, Yb)

Layered structures can facilitate “phonon-glass, electron-crystal (PGEC)” properties, which are crucial for the design of the state-of-the-art thermoelectric materials. In this report, two Mn-containing metastable Zintl phases with layered structures, Ca2MnSb2 and Yb2MnSb2, are discovered for the first time. Their structures are isotypic to that of LiZnSb with transition-metal sites partially occupied. Interestingly, these compounds feature very broad homogeneity ranges, which enable flexible tuning on the Mn sites. In addition, close relationships to previously reported Yb9Mn4+xSb9 series have been well established by phase exploration, and structure transition from Yb2MnSb2 to Yb9Mn4+xSb9 was experimentally observed after annealing. The thermal stability of A2MnSb2 (A = Ca, Yb) can be significantly improved through Ag doping on the Mn sites, based on which, systematic investigations on the crystal structures and thermoelectric properties were carried out. Benefited from the complex anionic structures, the thermal conductivity of these phases is extremely low, that is, the Yb-containing material Yb2(Mn0.9Ag0.2)Sb2 features glasslike thermal conductivity with a minimum value of 0.42 W·m–1·K–1 at 673 K, and meanwhile, a high Seebeck coefficient of 208 μV·K–1 was obtained at 673 K. The discovery of such A2MnSb2 (A = Ca, Yb) phases completed the critical missing members of the A–Mn–Sb ternary family, which is crucial for understanding the structure and properties related to these novel phases, and with the progress of such studies, the design of the state-of-the-art thermoelectric materials based on such Zintl phases is very promising.

Charge carrier mediation and ferromagnetism induced in MnBi6Te10 magnetic topological insulators by antimony doping

A new kind of intrinsic magnetic topological insulator (MTI) MnBi2Te4 family has shed light on the observation of novel topological quantum effects such as the quantum anomalous Hall effect (QAHE). However, strong anti-ferromagnetic (AFM) coupling and high carrier concentration in the bulk hinder practical applications. In closely related materials MnBi4Te7 and MnBi6Te10, the interlayer magnetic coupling is greatly suppressed by Bi2Te3 layer intercalation. However, AFM is still the ground state in these compounds. Here, by magnetic and transport measurements, we demonstrate that a Sb substitutional dopant plays a dual role in MnBi6Te10, which can not only adjust the charge carrier type and concentration, but also induces the solid into a ferromagnetic (FM) ground state. The AFM ground state region, which is also close to the charge neutral point, can be found in the phase diagram of Mn(Sb x Bi1−x )6Te10 when x ∼ 0.25. An intrinsic FM-MTI candidate is thus demonstrated, which may take us a step closer to realizing a high-quality and high-temperature QAHE and related topological quantum effects in the future.

Cooperative regulation of electrical and thermal transport behavior enhancing the thermoelectric performance of SnTe

SnTe is a kind of promising candidates for medium temperature thermoelectric materials, while its thermoelectric properties are limited by not only the poor electrical transport properties caused by intrinsic high carrier concentration and large valence bands offset, but also the relatively high lattice thermal conductivity. In this work, the thermoelectric performance of Mn–Bi and Mn–Sb co-doped SnTe is investigated. As expected, Mn doping decreases the energy separation between the two valence band maxima, enabling improved Seebeck coefficient, the donor effect of Bi or Sb weakens the adverse effect of Mn doping on carrier concentration, and then a relatively high average power factor is achieved. More importantly, a variety of defects, including point defects, dislocations and nanoprecipitates, are introduced, which can scatter phonons in a wide frequency range and decrease the lattice thermal conductivity. Finally, the synergy of these effects yields a maximum ZT of 1.14 at 873 K and an average ZT of 0.7 (300–873 K) in Sn0·88Bi0·04Mn0·08Te sample, and a maximum ZT of 1.23 at 873 K and an average ZT of 0.73 (300–873 K) in Sn0·82Sb0·06Mn0·12Te sample.

Engineering Electronic Structure and Lattice Dynamics to Achieve Enhanced Thermoelectric Performance of Mn–Sb Co-Doped GeTe

GeTe, as a p-type semiconductor, has been intensively studied in recent years as a promising lead-free mid-temperature-range thermoelectric (TE) material. Herein, we report an improved energy conve...

In situtrace elements and S isotope systematics for growth zoning in sphalerite from MVT deposits: A case study of Nayongzhi, South China

AbstractZoning texture in sphalerite has been described in many studies, although its genesis and ore formation process are poorly constrained. In this investigation, we compare thein situtrace element and isotopic composition of colour-zoned sphalerites from Nayongzhi, South China, to explain the zoning growth process. Petrographic observations identified two broad types of zoned sphalerite, core–rim (CR) and core–mantle–rim (CMR) textures. Each zoned sphalerite displays two or three colour zones, including brown core, light colour bands and/or pale-yellow zones.In situlaser ablation inductively coupled plasma mass spectrometry trace-element analyses show that the three colour zones display variable trace-element compositions. Brown cores exhibit distinctly high Mn, Fe, Co, Ge, Tl and Pb concentrations, whereas pale-yellow and light colour zones have elevated Ga, Cd, Sn, In and Sb concentrations. Copper, Sb, In and Sn show slight variations between pale-yellow and light zones, the latter having higher In and Sn, but lower Cu and Sb abundances. Given the low concentration range of Pb, Ge, Tl, Mn Sb, Cd, etc., the colour of sphalerite is attributed mainly to Fe compositional variation. The δ34S values of sphalerite from Nayongzhi range from +22.3 to +27.9‰, suggesting reduced sulfur was generated by thermochemical sulfate reduction of marine sulfate in ore-hosted strata. Single-crystal colour-zoned sphalerite exhibits intracrystalline δ34S variation (up to 4.3‰), which is attributed to the δ34S composition of H2S in the original fluid. The lack of correlation between trace elements and δ34S values indicates episodic ore solution influxes and mixes with the reduced sulfur-rich fluid derived from the aquifers of the ore-hosted strata, which play a key role in the formation of the zoned Nayongzhi sphalerite. In conclusion,in situtrace element and S isotope studies of zoned sphalerite crystals might provide insight into the ore-forming process of MVT deposits.

Ferromagnetism in van der Waals compound MnSb1.8Bi0.2Te4

The intersection of topology and magnetism represents a new playground to discover novel quantum phenomena and device concepts. In this work, we show that a van der Waals compound MnSb$_{1.8}$Bi$_{0.2}$Te$_4$ exhibits a ferromagnetic ground state with a Curie temperature of 26 K, in contrast to the antiferromagnetic order previously found for other members of the Mn(Sb, Bi)$_2$Te$_4$ family. We employ magneto-transport, bulk magnetization and neutron scattering studies to illustrate the magnetic and electrical properties of MnSb$_{1.8}$Bi$_{0.2}$Te$_4$ and report on the observation of an unusual anomalous Hall effect. Our results are an important step in the synthesis and understanding of ferromagnetic topological insulators.

Structural Complexity and High Thermoelectric Performance of the Zintl Phase: Yb21Mn4Sb18

Thermoelectric materials are a unique class of compounds that can recycle energy through conversion of heat into electrical energy. A new 21–4–18 Zintl phase has been discovered in the Yb–Mn–Sb sys...

Crystallographic orientation of primary and eutectic phases in a hypoeutectic Mn–Sb alloy induced by solidification in high magnetic fields

This paper investigates how applying high magnetic fields influences the crystallographic orientations of the primary and eutectic phases, and their relationship, in a binary eutectic alloy. At 0 T, the primary MnSb phase in hypoeutectic Mn–Sb showed a random orientation, but at 3, 6, 9 and 11.5 T, its c axis was perpendicular to the magnetic field direction. In all cases, the eutectic MnSb phases showed the same orientations as their neighboring primary MnSb phase, on which they nucleated and grew. With high magnetic fields, the c axes of the eutectic and primary MnSb phases were oriented perpendicular to the magnetic field direction. The results show that applying a high magnetic field during solidification is a way of controlling the crystallographic orientation of both the primary and the eutectic phases in eutectic alloys.

Rutile Alloys in the Mn–Sb–O System Stabilize Mn3+ To Enable Oxygen Evolution in Strong Acid

Electrocatalysis of the oxygen evolution reaction is central to several energy technologies including electrolyzers, solar fuel generators, and air-breathing batteries. Strong acid electrolytes are desirable for many implementations of these technologies, although the deployment of such device designs is often hampered by the lack of non-precious-metal oxygen evolution electrocatalysts, with Ir-based oxides comprising the only known catalysts that exhibit stable activity at low overpotential. During our exploration of the Mn–Sb–O system for precious-metal-free electrocatalysts, we discovered that Mn can be incorporated into the rutile oxide structure at much higher concentrations than previously known, and that these Mn-rich rutile alloys exhibit great catalytic activity with current densities exceeding 50 mA cm–2 at 0.58 V overpotential and catalysis onset at 0.3 V overpotential. While this activity does not surpass that of IrO2, Pourbaix analysis reveals that the Mn–Sb rutile oxide alloys have the same ...

Structure and Chemical Composition of Manganese-Doped GaSb Dislocations

Electron microscopic observations showed that the preparation of magnetic semiconductor GaSb〈Mn〉 by melt quenching is accompanied by discrete manganese precipitation on GaSb dislocations, this precipitation generating inclusions sized from a split micrometer to several micrometers. The chemical composition of microinclusions was determined by electron probe microanalysis. The superposition of the magnetic properties of compounds that are formed in the Mn–Sb system determines the magnetic properties of GaSb〈Mn〉.

High magnetic-field-induced solute interception among dendrite arms in the mushy zone of a Mn–Sb alloy

The effect of high magnetic fields on the solute diffusion behavior in the mushy zone of a Mn–Sb alloy has been investigated. A hypoeutectic Mn–Sb alloy was heated in high magnetic fields to yield a mixture of primary MnSb dendrites and Mn/Sb liquid to simulate the mushy state, annealed isothermally for various times, and quenched to room temperature. Without a magnetic field or with a 1-T field, the quenched alloy had a microstructure that was composed of MnSb particles that were dispersed in MnSb/Sb eutectics. At higher magnetic fields, a multiple-phase mixed microstructure that consisted of fine MnSb particles, bulk Sb, and MnSb dendrites and eutectic was observed at relatively short annealing times. The amounts of fine MnSb particles and bulk Sb decreased with an increase in annealing time but increased with an increase in magnetic-flux density. The appearance of the multiple-phase mixed microstructure can be attributed to solute interception in the mushy zone, which can change the solute distribution among the dendrite arms and which is caused by a high magnetic field that is based on the Lorentz force. The application of a high magnetic field to the mushy state of the alloys is proposed as an effective route for the in-situ control of solute diffusion in the mushy zone.

Compositional invariance of magnetocaloric effect near room temperature in Ni–Mn–Sb–Al systems

A systematic study of structural transformation, magnetism and magnetic entropy change in the vicinity of structural and magnetic transformation has been performed in the Ni2Mn1.36Sb0.64 by substituting Sb with a large amount of Al. This substitution enhanced the transformation temperature close to room temperature and also made it less sensitive to the variation in composition. Alloys exhibited conventional and inverse magnetocaloric effects due to the Curie and magnetostructural transformation respectively. The inverse magnetocaloric effects were less compared to those reported in pure Sb system, but it showed a large value of conventional magnetocaloric effect with the added advantage of insensitivity to the compositional variation.

Microstructural and Crystallographic Insights in a Martensite/Austenite Dual Phase Ni–Mn–Sb Alloy

For Ni–Mn–Sb multifunctional alloy, its microstructure and crystallographic information are decisive factors for its multiple magnetic field induced properties, such as magnetic field induced shape memory effect, magneto‐caloric effect, exchange bias effect, and so on. While, studies on such field are rarely conducted. In the present work, a thorough study on microstructural features and crystallographic characteristics has been conducted in a martensite/austenite dual phase coexisting polycrystalline Ni50Mn37Sb13 alloy. Results show that the martensite is self‐organized in plates in the original austenite. The intra‐plate martensite presents a fine lamellar microstructure and each fine lamella corresponds to one martensite variant. Crystallographic orientation analysis indicates that each martensite plate exists four differently oriented martensite variants and they can form three types of twins, type I, type II, and compound twin. Trace analysis results show that the interface between adjacent variants are their twinning plane K1. Further investigation on martensitic transformation orientation relationship reveals that the Pitsch orientation relationship, specified as //and //, is the effective one from austenite to martensite. All the above results offer basic microstructural and crystallographic information on Ni–Mn–Sb alloys and can be useful for further investigation on property optimization of these alloys.