Intermetallic FeSn Research Articles

Sn Anodes Protected by Intermetallic FeSn2 Layers for Long‐lifespan Sodium‐ion Batteries with High Initial Coulombic Efficiency of 93.8 %

AbstractWith a theoretical capacity of 847 mAh g−1, Sn has emerged as promising anode material for sodium‐ion batteries (SIBs). However, enormous volume expansion and agglomeration of nano Sn lead to low Coulombic efficiency and poor cycling stability. Herein, an intermetallic FeSn2 layer is designed via thermal reduction of polymer‐Fe2O3 coated hollow SnO2 spheres to construct a yolk‐shell structured Sn/FeSn2@C. The FeSn2 layer can relieve internal stress, avoid the agglomeration of Sn to accelerate the Na+ transport, and enable fast electronic conduction, which endows quick electrochemical dynamics and long‐term stability. As a result, the Sn/FeSn2@C anode exhibits high initial Coulombic efficiency (ICE=93.8 %) and a high reversible capacity of 409 mAh g−1 at 1 A g−1 after 1500 cycles, corresponding to an 80 % capacity retention. In addition, NVP//Sn/FeSn2@C sodium‐ion full cell shows outstanding cycle stability (capacity retaining rate of 89.7 % after 200 cycles at 1 C).

Sn Anodes Protected by Intermetallic FeSn2 Layers for Long-lifespan Sodium-ion Batteries with High Initial Coulombic Efficiency of 93.8.

With a theoretical capacity of 847 mAh g-1 , Sn has emerged as promising anode material for sodium-ion batteries (SIBs). However, enormous volume expansion and agglomeration of nano Sn lead to low Coulombic efficiency and poor cycling stability. Herein, an intermetallic FeSn2 layer is designed via thermal reduction of polymer-Fe2 O3 coated hollow SnO2 spheres to construct a yolk-shell structured Sn/FeSn2 @C. The FeSn2 layer can relieve internal stress, avoid the agglomeration of Sn to accelerate the Na+ transport, and enable fast electronic conduction, which endows quick electrochemical dynamics and long-term stability. As a result, the Sn/FeSn2 @C anode exhibits high initial Coulombic efficiency (ICE=93.8 %) and a high reversible capacity of 409 mAh g-1 at 1 A g-1 after 1500 cycles, corresponding to an 80 % capacity retention. In addition, NVP//Sn/FeSn2 @C sodium-ion full cell shows outstanding cycle stability (capacity retaining rate of 89.7 % after 200 cycles at 1 C).

Anti-pulverization intermetallic Fe–Sn anchored on N-doped carbon anode boosted superior power and stable lithium storage

Tin (Sn) anode suffers from considerable volume deformation, generating vast dilatation-induced stresses leading to pulverization for lithium-ion batteries (LIBs). Herein, the Sn–Fe–C composite anode material with a jujube cake-like structure where Sn/FeSn2 metalcore anchored on an N-doped carbon matrix is constructed. During the lithiation process, the intermetallic Fe–Sn (FeSn2) generates Fe nanoparticles, which are uniformly distributed in the Sn matrix to relieve internal stress and create a conductive network, thus enhancing electron conduction and ion diffusion kinetics. In addition, the N-doped carbon matrix maintains the material structural integrity and improves overall conductivity. Consequently, the Sn–Fe–C anode delivers a high reversible 400 mAh g−1 over 1100 cycles at 5 A g−1 (capacity retention of up to 90.9%) and rate performance (237 mAh g−1 at 20 A g−1). Sn–Fe–C anode pairs with porous carbon (PC) cathode to assemble lithium-ion capacitors (Sn–Fe–C || PC LICs), which show a maximum energy density of 203.8 Wh kg−1, an excellent power density of 23925.3 W kg−1, and energy retention rate of 72.9% after 18,000 cycles at 1 A g−1. The Sn–Fe–C material as an anti-pulverization anode could be a potential application for high-performance LIBs and LICs in the future.

Evaluation of interaction between Sn and passivated stainless steel through an easy chromaticity approach

The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach. The microstructure of Fe–Sn intermetallics (IMCs) was observed, and their growth was inspected at different time after the interaction. The oxide film on stainless steel exposed in air locally delayed IMC growth, and the chemically passivated film protected stainless steel from Fe–Sn compound formation. To investigate the interaction mechanism, the integrity of passivated films grown on stainless steel was evaluated by chromogenic inspection. The interaction extent was related to colour measurement a*. Results indicated that the measured value of a* from the inspection decreased with the increasing exposure time, and a minimum a* value was found in chemically passivated samples. The tendency of the colour measurement was consistent with the effect of passive film on IMC growth. The interfacial reaction of passivated stainless steel with Sn was illustrated based on the integrity of the passive films.

Effect of Surface Fe-Sn Intermetallics on Oxide Films Formation of Stainless Steel in High Temperature Water

AbstractThe oxidation of stainless steel with Fe-Sn intermetallics adhesion in 300 °C water was studied by analyzing the morphologies and phase structures of surface oxide films. The oxidation behavior of stainless steel was discussed in order to illustrate the effect of Fe-Sn intermetallics on the oxidation characteristic. Larger size of faceted spinel and small size of SnO2 particles are observed on the samples with Fe-Sn intermetallics adhesion, whereas smaller faceted hematite and spinel grow on the samples without Fe-Sn intermetallics adherence. The surface intermetallics aggravates the spalling of oxide particles and decreases the corrosion resistance of stainless steel. Such deterioration is attributed to the loose microstructure characteristic and the poor corrosion resistance of SnO2 particles formed in high temperature water.

Role of intermetallics on fatigue behaviuor of stainless steel adhered by Sn

The fatigue property of 304 stainless steel (SS) adhered by Fe-Sn intermetallics was investigated. The microstructure of crack nucleation and crack propagation was observed, and the influence of Fe-Sn intermetallics on fatigue failure was analyzed. Fatigue tests at stress ratio of R = −1 were performed using a sine waveform at 20 Hz frequency under load control. In addition, the morphology and microfractography of the Fe-Sn intermetallics were examined under a scanning electron microscope. Results demonstrated that the adherence of the interfacial (Fe, Cr)Sn2 layer reduced the fatigue life of the 304 SS substrates. The fatigue cracks also exhibited the intergranular fracture characteristics of the intermetallics. The brittle (Fe, Cr)Sn2 intermetallics were apt to fatigue crack nucleation. The interfacial metallurgical bonding, which was caused by diffusion reaction between Fe and Sn atoms, led to crack propagation into the SS substrate.

Fe-Sn Intermetallics Synthesized via Mechanical Alloying-Sintering and Mechanical Alloying-Thermal Spraying

Iron (Fe)-tin (Sn) intermetallics were synthesized by using two different routes. These two routes had a common synthesis step, in which Fe powder (19 wt. %) was mechanically alloyed with Sn powder (81 wt. %) for 25 h under argon atmosphere. The mechanically alloyed powders were then treated with different heating routes. In the first route, the compacts of the mechanically alloyed powders were sintered at different temperatures for different times. It was found that the FeSn2 content increased with increasing temperature and time. There were small traces of Fe, Sn and FeSn found in the sintered materials. In the second route, the mechanically alloyed powders were plasma-sprayed using different currents of 300, 400 and 500 A. It was found that the porous coatings produced by plasma sprayng consisted of mixed Fe, Sn, FeSn2, SnO, FeO and Fe3O4 for all employed currents.

Laser processing issues of nanosized intermetallic Fe–Sn and metallic Sn particles

Intermetallic Fe–Sn and nanocrystalline metallic Sn nanoparticles have been successfully synthesized from organic precursors using the laser pyrolysis technique with ethylene as sensitizer. Nano-structured Sn (single phase) was prepared by the pyrolysis of Sn(CH3)4 (TMT) vapors. Controlled Fe/Sn atomic ratios, ranging from 0.69 to 1.64 were obtained for the prepared Fe–Sn nanopowders by the control of Fe(CO)5 and TMT flows, respectively. XRD studies evidence three main phases: the tetragonal metallic Sn phase and the intermetallic FeSn2 phase and, to a much lesser extent, the cubic ternary carbide Fe3SnC. Complex core–shell structural characteristics were found by HRTEM analysis. More complete information about the Fe phase distributions in the new intermetallic Fe–Sn nanomaterial is provided by temperature dependent 57Fe Mössbauer spectroscopy.

Nanospheres of a New Intermetallic FeSn5 Phase: Synthesis, Magnetic Properties and Anode Performance in Li-ion Batteries

We synthesized monodisperse nanospheres of an intermetallic FeSn(5) phase via a nanocrystal-conversion protocol using preformed Sn nanospheres as templates. This tetragonal phase in P4/mcc space group, along with the defect structure Fe(0.74)Sn(5) of our nanospheres, has been resolved by synchrotron X-ray diffraction and Rietveld refinement. Importantly, FeSn(5), which is not yet established in the Fe-Sn phase diagram, exhibits a quasi-one dimensional crystal structure along the c-axis, thus leading to interesting anisotropic thermal expansion and magnetic properties. Magnetization measurements indicate that nanospheres are superparamagnetic above the blocking temperature T(B) = 300 K, which is associated with the higher magnetocrystalline anisotropy constant K = 3.33 kJ m(-3). The combination of the magnetization measurements and first-principles density functional theory calculations reveals the canted antiferromagnetic nature with significant spin fluctuation in lattice a-b plane. The low Fe concentration also leads Fe(0.74)Sn(5) to enhanced capacity as an anode in Li ion batteries.

Formation and characterization of intermetallic Fe–Sn nanoparticles synthesized by an arc discharge method

Intermetallic Fe–Sn nanoparticles were prepared by a DC arc discharge method and investigated using X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and differential scanning calorimetry (DSC) analysis. The synthesized nanoparticles have a shell/core structure with an SnO 2 shell of 5–10 nm in thickness and a core of polycrystalline intermetallic compounds. It was found that the intermetallic compounds FeSn 2 and Fe 3Sn 2 were generated and coexist with the Sn phase as a single nanoparticle. The DSC analysis showed that Fe–Sn nanoparticles have high oxidation resistance in air. A mechanism of the nanoparticle formation was also interpreted on the basis of experimental results and thermodynamic principles.

High pressure X-ray diffraction study of all Fe–Sn intermetallic compounds and one Fe–Sn solid solution

Abstract The present study describes the preparation of all five Fe–Sn intermetallic compounds, FeSn 2 , FeSn, Fe 3 Sn 2 , Fe 5 Sn 3 , and Fe 3 Sn, and the results of the X-ray diffraction study under static high pressure up to 25 GPa using nitrogen as a pressure-transmitting medium. The samples were prepared with phase purities of 97% and higher. Four Fe–Sn intermetallics, FeSn 2 , FeSn, Fe 5 Sn 3 , and Fe 3 Sn, show no phase transition to the highest pressure achieved; Fe 3 Sn 2 undergoes two transitions to 25 GPa. The bulk moduli of these materials decrease approximately linearly with increasing Sn content, with the exception of Fe 3 Sn 2 . We also studied the solubility of Sn in α-Fe (α-Fe 1− x Sn x ). Tin expands the α-Fe lattice according to Vegard's law to at least 6 at.% Sn. The solid solution α-Fe 0.92 Sn 0.08 was examined beyond the pressure of the α/ɛ-phase transition. The onset of the phase transition in α-Fe 0.92 Sn 0.08 occurs at about 24 GPa, higher than the transition pressure of 14 GPa in pure α-Fe, but at a similar lattice parameter, a ≈ 2.800 A.

Spreading of Sn-Ag solders on FeNi alloys

The spreading of Sn-3Ag-xBi solders on Fe-42Ni has been studied using a drop transfer setup. Initial spreading velocities as fast as ~0.5 m/s have been recorded. The results are consistent with a liquid front moving on a metastable, flat, unreacted substrate and can be described by using a modified molecular-kinetic model for which the rate controlling step is the movement of one atom from the liquid to the surface of the solid substrate. Although the phase diagram predicts the formation of two Fe-Sn intermetallics at the solder/substrate interface in samples heated at temperatures lower than 513 °C, after spreading at 250 °C only a thin FeSn 2 reaction layer could be observed. Two interfacial layers (FeSn and FeSn 2) were found after spreading at 450 °C.

57Fe Conversion Electron Mössbauer Spectroscopy of Factors Influencing Fe–Sn Intermetallic Phase Formation in Tinplated Steel

The formation of intermetallic phases influences the properties of commercial alloys. CEMS can be used to reveal the presence of Fe-Sn intermetallics at the interface on tinplated steels. The work presented investigates the sensitivity of CEMS to detect intermetallics. Varying amounts of Fe-Sn intermetallics have been identified by CEMS having been produced by heat treating samples of tinplated steel at selected temperatures and times. The effect of surface roughness of the substrate on the Mossbauer signal has also been investigated. The intermetallic formation was found to reach a limiting value with increased heat treatment. Using CEMS, intermetallic formation was observed at temperatures as low as 190°C. Sample roughness was found to affect intermetallic formation and their observation using CEMS and GA-XRD.

Electron spectroscopic studies of tin surface segregation on iron single crystal surfaces

AES, ELS, LEED and XPS investigations of the surface segregation of tin dissolved in a Fe-4wt%Sn alloy were performed in ultra-high vacuum at elevated temperatures. The three low indexed surface orientations (100), (110) and (111) were studied. In all cases, no dependence of the maximum tin surface coverage on temperature was detected within the temperature range from 450 to 650°C. An order-disorder transition was observed by LEED, AES and XPS for the (100) oriented surface during tin segregation. The binding state for the segregated tin atoms abruptly changes at the order-disorder transition as determined by XPS. Similar results were obtained for the (111) surface. A deviating behaviour was observed for the (110) surface orientation, where two different ordered hexagonal surface structures were detected by LEED during tin surface enrichment. The first structure is similar to the diamond structure of pure tin, and the second one corresponds to the formation of a thin layer of the intermetallic compound FeSn on the (110) surface. The electron binding energies of the segregated tin atoms determined by XPS increase with increasing tin coverage on the (110) oriented surface. ELS studies on (100) and (111) oriented surfaces saturated with segregated tin show in comparison with literature data of pure tin a surface plasmon loss peak but no signal for the corresponding bulk loss. An energy loss signal found only for the (110) surface at Sn saturation coverage seems to be characteristic of an intermetallic FeSn surface phase.