Metallic Phase Research Articles

Improved conduction and orbital polarization in ultrathin LaNiO3 sublayer by modulating octahedron rotation in LaNiO3/CaTiO3 superlattices.

Artificial oxide heterostructures have provided promising platforms for the exploration of emergent quantum phases with extraordinary properties. Here, we demonstrate an approach to stabilize a distinct oxygen octahedron rotation (OOR) characterized by in the ultrathin LaNiO3 sublayers of the LaNiO3/CaTiO3 superlattices. Unlike the OOR in the LaNiO3 bare film, the OOR favors high conductivity, driving the LaNiO3 sublayer to a metallic state of ~100 K even when the layer thickness is as thin as 2 unit cells (u.c.). Simultaneously, strongly preferred occupation of orbital is achieved in LaNiO3 sublayers. The largest change of occupancy is as high as 35%, observed in the 2 u.c.-thick LaNiO3 sublayers sandwiched between 4 u.c.-thick CaTiO3 sublayers. X-ray absorption spectra indicate that the OOR pattern of LaNiO3 achieved in the LaNiO3/CaTiO3 heterostructures has significantly enhanced the Ni-3d/O-2p hybridization, stabilizing the metallic phase in ultrathin LaNiO3 sublayers. The present work demonstrates that modulating the mode of OOR through heteroepitaxial synthesis can modify the orbital-lattice correlations in correlated perovskite oxides, revealing hidden properties of the materials.

First principles investigations on structural, electronic, optical, and thermodynamical properties of bulk and surfaces of In2CO

This study reports first-principles investigations of the structural, electronic, thermal, and optical properties of a novel material In2CO in bulk phase and slab models in (001), (100), (101), and (011) orientations to develop a fundamental understanding of its characteristics. The material appeared structurally as well as dynamically stable in the orthorhombic phase. The thermal properties demonstrated that the material's heat capacity is more temperature-sensitive than entropy and enthalpy. The electronic band structure analysis revealed that the orthorhombic phase material is a semiconductor with a narrow indirect band gap. The electronic structures modeled using the spin-orbit coupling yielded the metallic phase of the slabs except for (001) orientation. The electromagnetic absorption characteristics of the compound are also investigated to explore the material's potential in optoelectronic applications. The direction-dependent study of optical characteristics revealed that the (001) slab of the material can be an efficient infrared detector. The survey findings provide instrumental outcomes in utilizing In2CO in electronic and optoelectronic applications.

Demineralized cancellous bone scaffolds as reinforcement for degradable magnesium biocomposite

AbstractThis study investigates demineralized bone matrix (DBM) combined with magnesium (Mg) to create degradable composite materials. Two types of DBM were utilized: carbon-coated (H.A.) and non-carbon-coated (HA-HT). An advanced liquid metal infiltration method prevented the structural collapse of the scaffold due to capillary forces. Both composites exhibited an interphase layer primarily composed of MgO, differing in thickness by 50%, attributed to the reaction between H.A. and Mg. The Mg/H.A. composite demonstrated a compressive yield strength 1.7 times higher than Mg/HA-HT, resembling Mg’s mechanical behavior but with a lower metal phase fraction than other composites. Compared to pure Mg, the composites generated less hydrogen (45–54 ml cm−2), reducing the corrosion rate (~ 0.1181 mm year−1) under simulated conditions (90 ml cm−2 and 4.2 mm year−1 for Mg). A localized phenomenon was identified mainly at the interphase of both composites but specifically in the Mg/H.A., where the scaffold structure was kept over extended exposure periods. These materials hold promise for temporary bone fixation applications. Graphical abstract

Indene as an alternative hydrogen carrier: Performance of supported noble metal catalysts for indene and indane hydrogenation

We propose in this article the use of indene, obtained from the light fraction of coal tar rectification, as a Liquid Organic Hydrogen Carrier (LOHC), with a thorough study of its hydrogenation. The hydrogenation process, conducted on noble metal catalysts (Pd, Pt, Rh, and Ru) supported by activated carbon or alumina, involves the rapid conversion of indene to indane, followed by the formation of cis- and trans-hydrindane. Carbon-supported catalysts exhibited faster reactions rates, with catalytic activities varying among metal phases, Rh and Ru being the most active. Indene was found to have an inhibitory effect on the hydrogenation reactions. While Ru catalysts enhance cracking, Rh catalysts are the most selective for total hydrogenation. The study highlights that Ru catalysts favour cracking reactions more than Rh. The proposed reaction mechanisms involve successive steps and follow a Langmuir-Hinshelwood type kinetics, confirming the inhibitory effect of indene.

Size-based separation of fine mineral particles using inertial microfluidics: A case of jarosite and anglesite

Many metal phases in industrial hazardous waste coexist as fine mineral particles (FMPs, with particle sizes of 0.01 μm–10 μm) in a physical mixture, making conventional methods unable to achieve separation. Advanced microfluidics has demonstrated its potential in the separation of FMPs, as exemplified by jarosite and anglesite. Our study innovatively proposed an inertial microfluidic method for the separation of FMPs by force difference in curved microchannels, thus produced two distinct migration behaviors and subsequent separation. In addition, the computational fluid dynamics (CFD) simulation model was constructed to predict and analyze the migration behavior and separation trend of FMPs through flow field simulation and particle trajectory tracking. The results indicated that 2.1 μm and 3.6 μm small particles migrated to the outer outlet of the microchannel due to the dominant Dean vortex force, while 7.2 μm and 9.4 μm large particles migrated to the inner outlet relying on inertial focusing. At a flow rate of 1.2 mL/min, the separation efficiency of 3.6 μm jarosite and 9.4 μm anglesite has achieved a leap from 0 % to 60.7 %. This discovery provided feasibility and insights into the application of microfluidic technology for particle separation, and offered enormous potential for practical iron residue treatment.

Target Immobilized Phases of Heavy Metals in Hazardous Waste Based Lightweight Aggregate

Target Immobilized Phases of Heavy Metals in Hazardous Waste Based Lightweight Aggregate

Very low Ru loadings boosting performance of Ni-based dual-function materials during the integrated CO2 capture and methanation process

Herein, the effect of the Ru:Ni bimetallic composition in dual-function materials (DFMs) for the integrated CO2 capture and methanation process (ICCU-Methanation) is systematically evaluated and combined with a thorough material characterization, as well as a mechanistic (in-situ diffuse reflectance infrared fourier-transform spectroscopy (in-situ DRIFTS)) and computational (computational fluid dynamics (CFD) modelling) investigation, in order to improve the performance of Ni-based DFMs. The bimetallic DFMs are comprised of a main Ni active metallic phase (20 wt%) and are modified with low Ru loadings in the 0.1–1 wt% range (to keep the material cost low), supported on Na2O/Al2O3. It is shown that the addition of even a very low Ru loading (0.1–0.2 wt%) can drastically improve the material reducibility, exposing a significantly higher amount of surface-active metallic sites, with Ru being highly dispersed over the support and the Ni phase, while also forming some small Ru particles. This manifests in a significant enhancement in the CH4 yield and the CH4 production kinetics during ICCU–Methanation (which mainly proceeds via formate intermediates), with 0.2 wt% Ru addition leading to the best results. This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO2 capture atmosphere. The formation rate of CH4 during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters, including the H2 inlet concentration, inlet flow rate, dual-function material weight, and reactor internal diameter.

Comprehensive approach on La1-xPbxMnO3 (0.2 ≤ x ≤ 0.5) perovskites synthesized by solid state reaction technique

We have synthesized Pb concentrated La manganites La1-xPbxMnO3 (0.2 ≤ x ≤ 0.5) using solid state reaction route to investigate several physical properties such as structural, thermal, magnetic, electronic and elastic properties via both the experimental characterizations and the first principles calculations under the framework of density functional theory (DFT). The structures of the studied perovskites are examined by X-ray diffraction (XRD) pattern and also compared with the crystallographic data obtained by computations. The crystallization and formation of the studied phase of manganites are confirmed by analyzing the thermogravimetric (TG) curve. The temperature dependence of magnetization of all the samples exhibits a ferromagnetic metal phase with the Curie temperatures TC ranging from 334 to 338K. Although a metal-semiconductor transition is expected at around TC for the measurement of electrical resistivity with temperature but we observe semiconducting behavior because of the resistivity data started from room temperature. The calculated energy dispersion of all the manganites shows metallic conduction in conformity with the available experimental results. All the studied perovskites under investigation possess mechanical stability, malleability as well as anisotropy. The calculated Debye temperatures of all the Pb-doped La manganites show excellent correspondence with the other thermophysical parameters like melting point, phonon thermal conductivity and hardness as well.

Design and fabrication of tetradymites-based vertically oriented single and multilayer thin-film thermoelectric generators

Tetradymites-based thermoelectric materials and devices have received renewed attention due to their engineering and design flexibility, large scalability, and commercial viability in producing electricity from waste heat for niche applications in small power generation and micro refrigeration. In fact, most commercially available bulk thermoelectric generators (TEGs) are made from tetradymites. In contrast to their bulk counterparts, thin-film vertical TEGs have not been widely adopted. This can be attributable to complexities in design and fabrication methodologies, device measurement challenges, and the hurdle of maintaining a large enough temperature gradient for optimal device performance. In this study, we utilize a facile approach for the design, fabrication, and characterization of tetradymite-based n-type Bi2Te3 and p-type Sb2Te3 single-layer thermoelectric generators, as well as n-type Bi2Te3/Bi2Te2.83Se0.17 and p-type Sb2Te3/Bi0.4Sb1.6Te3 alternating multilayer superlattice TEGs. State-of-the-art characterization techniques were employed to investigate the structural, chemical, and thermoelectric properties of the materials. XRD analysis showed a preferential orientation along the (100) plane with a high intensity peak at 2θ = 25.5°, and XPS spectra exhibited a high-resolution peak at 531.5 eV corresponding to the Bi 4f7/2 core level. The structural data analysis confirmed the dominant metallic phase of the materials as well as their high crystalline nature. Device characterization showed that the multilayer device performed better than the single-layer devices with a recorded voltage, power, and power density of 11 mV, 12 pW, and 15.87 mW/m3 at ΔT = 18 °C, respectively, in comparison to 9.4 mV, 7.8 pW, and 10.31 mW/m3 for the most performing single-layer devices.

Fabrication and characterization of nacre-inspired metal/ceramic composites containing AlN nanowhiskers

Nacre-like composites prepared by infiltrating ice-templated porous ceramic-scaffolds with molten metal phases have successfully imitated the strengthening and toughening mechanisms of nacre at different lengthscales from macro to micro, but have not yet been able to replicate the nanoscale toughening mechanisms of nacre, which limits the further improvement in mechanical properties of the nacre-inspired composites. To resolve this issue, we prepared nacre-inspired Al/SiC composites containing AlN nanowhiskers by in-situ growth of whiskers during the spontaneous infiltration process of Al-10wt.%Mg alloy into an ice-templated porous SiC skeleton. It was found that the oxidation of the SiC skeleton had a significant impact on the growth of AlN nanowhiskers, as well as the phase composition and mechanical properties of the composites. When the skeleton was oxidized at 1100 ° C in air for 2 hours, the composite exhibited a large number of AlN whiskers and the optimal phase composition, while the flexural strength and fracture toughness of the composite reached their maximum values. The strengthening and toughening mechanisms, such as plastic deformation, crack deflection, multiple cracking, crack bridging, crack branching, and delamination, caused by the lamellar structure were observed. It was also found that the pull-out and bridging of the AlN whiskers provided strengthening and toughening effects at the nanoscale for the nacre-like composites.

Copper based high temperature heat storage macrocapsules with optimized inner cavity

The development of practical high temperature metallic phase change macrocapsules still faces difficulties, because metallic phase change materials undergo volume expansion during phase transformations, which can lead to outer shell rupture. When a core made of stacked metal powders is used, a cavity is eventually formed inside the capsule that acts as a cushion for volume expansion, thus reducing the risk of capsule rupture. However, the cavity will weaken the thermal storage capacity of the capsule, and in order to obtain a capsule with good thermal storage capacity and long-time cycling stability, it is necessary to find a suitable cavity volume of the capsule. In this paper, Cu powders are used as the core raw material, which are spherelized into millimeter level spheres, and the Cu powder spheres are isostatically pressed using an isostatic presser under different pressures to achieve the optimization of the cavity volume by reducing the gap between the powders. The high strength α-Al2O3 is selected as the shell, and sintering additives MgO and SiO2 are doped into the raw material, and the Cu@MgO-SiO2/Al2O3 capsules are prepared after two-step sintering treatment. The material properties and thermal storage properties of the capsules are investigated in detail, which have strong thermal storage properties, for example, in the temperature interval of 1000-1100 ℃, capsules with a core-shell structure (named as 9@1.5-100MPa, prepared with initial diameter of Cu core of 9mm, shell thickness of 1.5mm, and isostatic pressing under 100MPa to the core precursor) exhibit a high heat storage density of 222J/g and 841 MJ/m³. In addition, we conduct melting-solidification cycle tests, which confirms the excellent durability of the capsules. The comprehensive results show that the Cu@MgO-SiO2/Al2O3 macrocapsules possess strong thermal storage capacity and can be used as effective thermal storage materials, especially in advanced high temperature thermal storage systems.

Novel Janus [formula omitted]-Au[formula omitted]XY (X/Y = S, Se, Te) monolayers with ultra-high carrier mobility: A first-principles study

In this paper, we theoretically propose a series of Janus α-Au4XY (X/Y = S, Se, Te; X ≠ Y) monolayers and investigate their structural stability, electronic features, and transport properties based on first-principle calculations. It is indicated that Janus α-Au4XY monolayers have a structurally stable and can be synthesized experimentally. Janus α-Au4XY monolayers exhibit a low Young’s modulus and their mechanical features are slightly anisotropic. At the ground state, Janus α-Au4XY monolayers possess semiconducting characteristics with very steep band dispersions near the conduction band minimum, which is expected to ultra-high electron mobility. The electronic features of Janus α-Au4XY are highly sensitive to the biaxial strains ɛxy, particularly the applied compressive biaxial strains. Interestingly, the transitions from the semiconductor to the metal phases are observed in all three configurations of α-Au4XY at ɛxy=−6%. Janus α-Au4XY monolayers exhibit superior transport characteristics with the electron mobility reaching up to 3.20×105 cm2V−1s−1 (α-Au4SSe monolayer). Our findings not only explore the outstanding electronic and transport features of Janus α-Au4XY nanostructures but also indicate their potential applications in nanoelectronics and nanoelectromechanical devices.

Enhancement on mechanical properties via phase separation induced by Cu-added high-entropy alloy fillers in metastable ferrous medium-entropy alloy welds

This study evaluated the weldability of metastable ferrous medium-entropy alloys using high-entropy alloy fillers with various Cu contents and elucidated the strengthening mechanisms at room and cryogenic temperatures by focusing on the formation of a Cu-rich phase (FCC2) in the weld metal (WM). The WM with higher Cu content exhibited more dual face-centered cubic (FCC) phases with dendrite-shaped compositional heterogeneity due to phase separation driven by higher mixing enthalpy. The FCC2 induced greater lattice distortion, resulting in higher nano-hardness and stronger solid-solution hardening. In addition, the increased presence of FCC2 in the WM promoted grain refinement and the formation of additional grain boundaries within individual grains. After cryogenic deformation, the base metal and heat-affected zone in transverse welds underwent martensitic transformation from metastable FCC (transformation-induced plasticity), while the diluted WMs exhibited twinning-induced plasticity because of their higher stacking fault energy (SFE) compared to the base metal. The combination of these deformation mechanisms enhanced the cryogenic tensile properties without compromising ductility. Furthermore, the cryogenic tensile properties of weld with higher Cu content were further improved due to the increased formation of deformation twins in the WM. The consumption of solute Cu to form more Cu-rich FCC2 resulted in compositional variations in the matrix (FCC1), leading to a further reduction in the SFE of FCC1 and the activation of additional twin formation. Additionally, FCC2 with a relatively higher SFE refined secondary twins as well as contributed to further dislocation accumulation. This study suggests that the formation of Cu-rich phase in the WM can enhance mechanical properties at both room and cryogenic temperatures and provides a valuable approach for the future development of welding materials to improve the mechanical properties of FCC-based welded structures.

Evaluation of Thermal and Mechanical Properties of Bi-In-Sn/WO3 Composites for Efficient Heat Dissipation.

Phase change materials (PCMs) offer promising solutions for efficient thermal management in electronic devices, energy storage systems, and renewable energy applications due to their capacity to store and release significant thermal energy during phase transitions. This study investigates the thermal and physical properties of Bi-In-Sn/WO3 composites, specifically for their use as phase change thermal interface materials (PCM-TIMs). The Bi-In-Sn/WO3 composite was synthesized through mechanochemical grinding, which enabled the uniform dispersion of WO3 particles within the Bi-In-Sn alloy matrix. The addition of WO3 particles markedly improved the composite's thermal conductivity and transformed its physical form into a putty-like consistency, addressing leakage issues typically associated with pure Bi-In-Sn alloys. Microstructural analyses demonstrated the existence of a continuous interface between the liquid metal and WO3 phases, with no gaps, ensuring structural stability. Thermal performance tests demonstrated that the Bi-In-Sn/WO3 composite achieved improved thermal conductivity, and reduced volumetric latent heat, and there was a slight increase in thermal contact resistance with higher WO3 content. These findings highlight the potential of Bi-In-Sn/WO3 composites for utilization as advanced PCM-TIMs, offering enhanced heat dissipation, stability, and physical integrity for high-performance electronic and energy systems.

Mott resistive switching initiated by topological defects

Avalanche resistive switching is the fundamental process that triggers the sudden change of the electrical properties in solid-state devices under the action of intense electric fields. Despite its relevance for information processing, ultrafast electronics, neuromorphic devices, resistive memories and brain-inspired computation, the nature of the local stochastic fluctuations that drive the formation of metallic regions within the insulating state has remained hidden. Here, using operando X-ray nano-imaging, we have captured the origin of resistive switching in a V2O3-based device under working conditions. V2O3 is a paradigmatic Mott material, which undergoes a first-order metal-to-insulator phase transition together with a lattice transformation that breaks the threefold rotational symmetry of the rhombohedral metallic phase. We reveal a new class of volatile electronic switching triggered by nanoscale topological defects appearing in the shear-strain based order parameter that describes the insulating phase. Our results pave the way to the use of strain engineering approaches to manipulate such topological defects and achieve the full dynamical control of the electronic Mott switching. Topology-driven, reversible electronic transitions are relevant across a broad range of quantum materials, comprising transition metal oxides, chalcogenides and kagome metals.

Sintering of c-BC2N, Solid Solutions of Metallic Phases Particles with the Additives of Oxide Components and NiCr at Ultra-High Load and Temperature of Spark-Plasma Sintering, High Compaction Pressure During the Explosive Method

Sintering of c-BC2N, Solid Solutions of Metallic Phases Particles with the Additives of Oxide Components and NiCr at Ultra-High Load and Temperature of Spark-Plasma Sintering, High Compaction Pressure During the Explosive Method

Electrodeposition of Thin Film Cu-Zn-Sn Alloy for Water Splitting Application

An energy transition to renewable energy sources is necessary due to the scarcity of fossil fuels and their detrimental effects on the environment. Water splitting process is one of the practical and effective way that does not occur spontaneously. This study investigates catalytic activity of Cu-Zn-Sn (CZT) photocatalyst in hydrogen evolution and oxygen evolution reaction. The CZT deposited with varied electrolyte’s pH of 6 and 9 on indium tin oxide substrate at the room temperature for 600 seconds. According to the X-ray diffraction patterns, there were Cu6Sn5, Cu5Zn8, and Sn metal phases with monoclinic, cubic, and cubic crystal systems. The scanning electron microscopy technique results of all CZT alloy sample showed a dense, non-uniform, and polycrystalline surface structure. The CZT alloys were found to have an average particle size of 0.35 μm. CZT alloys can produce a photocurrent density of 0.19 mA/cm² at a potential of 1.29 V vs RHE. the charge transfer resistance of CZT synthesized at pH 6 is lower (21.48 Ω) compared to pH 9 (28.36 Ω). The Tafel slope of HER for pH 9 CZT was -133 mV/dec, which was lower than that of pH 6 CZT (-88 mV/dec), indicating faster H2 production and corrosion resistance on pH 9 CZT.

Selective Reduction of Iron in High-Phosphorus Oolitic Ore from the Lisakovsk Deposit.

Reduction of iron in high-phosphorus oolitic ore from the Lisakovsk deposit using solid carbon, carbon monoxide, and hydrogen. An X-ray phase analysis was used to determine the phase composition of the samples after reduction roasting. When reduced with carbon monoxide or hydrogen, α-iron appears in the samples, while phosphorus remains in the form of iron, calcium, and aluminum phosphates. After roasting with solid carbon, phosphorus is reduced from iron and calcium phosphates and migrates into the metal but remains in aluminum phosphate. A micro X-ray spectral analysis showed that at a temperature of 1000 °C and a holding time of 5 h, during reduction with solid carbon, the phosphorus content in the metallic phase reaches up to 7.1 at. %. When reduced with carbon monoxide under the same conditions, the metallic phase contains only iron, and phosphorus is found only in the oxide phase. When reduced with hydrogen at 800 °C, phosphorus is almost absent in the metallic phase, but at 900 °C, phosphorus is reduced and its content in the metallic phase reaches 2.1 at. %.

Recrystallization Behavior of Computationally Optimized Low‐Alloy Steel at Various Temperatures and Strain Rates

The dynamic recrystallization (DRX) behavior of SA508‐III steel, a critical material for reactor pressure vessels (RPVs) normally treated by hot forging, is thoroughly examined in this article. In the investigation, elevated temperatures and the coarsening of metallic phases and carbides are revealed to contribute to the degradation of the steel's strength–toughness relationship. Utilizing computational thermodynamics, the stability of secondary phases, including carbides and brittle inclusions, is simulated to enable precise phase equilibrium calculations and accurate prediction of key mechanical properties such as yield strength, tensile strength, and hardness. These simulations facilitated targeted modifications to the alloy composition to enhance the steel's strength and hardenability under high‐temperature, high‐pressure conditions. In this study, alloy composition and processing parameters within the CALculation of PHAse Diagram framework, utilizing the ThermoCalc and JMatPro software packages, are optimized. In the microstructural investigations conducted under various isothermal deformation conditions (1173–1473 K) and strain rates (0.001–1 s−1), it is demonstrated that DRX mechanisms led to varied grain size developments, with a critical strain rate identified at 0.01 s−1 during high‐temperature deformations. In these findings, significant insights are provided into optimizing the mechanical performance of SA508‐III steel for RPV applications.

Active infrared tuning of metal–insulator-metal resonances by VO2 thin film

VO2 is a promising phase change material offering a large contrast of electric, thermal, and optical properties when transitioning from semiconductor to metallic phase. Here we show that a hybrid metamaterial obtained by proper combination of a VO2 layer and a nanodisk gold array provides a tunable plasmonic gap resonance in the infrared range. Specifically, we have designed and fabricated a metal–insulator-metal gap resonance by inserting sub-wavelength VO2 film between a flat gold layer and a gold nanodisk resonator array. The resonance of the hybrid metamaterial is centered in the useful 3–5 μm range when VO2 is in its semiconductor state. The experimental study highlights a monotonical spectral tuning of the resonance when increasing temperature up to 50 °C above the room temperature, providing a continuous resonance shift of almost 1 μm in the mid-infrared range. Wavelength range and intensity tunability can be further optimized by modifying the thicknesses of the layers and metamaterial parameters.