Ternary Compounds Research Articles

In Situ Electronic Structure Analysis of Water-Corroded UNx in High Vacuum

Nitriding technologies are promising surface modification techniques of uranium based on pulsed laser irradiating and glow plasma treatment. Nitrided layers with different nitrogen contents (UN0.35, UN0.75, UN1.08 and UN1.5) were prepared on the surface of uranium. The present study aims to investigate the microstructure and corrosion properties of the reaction of the UNx layers with ultra-low water vapor at room temperature. The electronic structures were analyzed in situ by X-ray photoelectron spectroscopy in high vacuum. The results showed that the UN0.35, UN0.75, and UN1.08 samples were mainly composed of uranium nitride (UN) and metallic uranium, while the surface microstructure of the UN1.5 sample was U2N3. The dense and uniform nitride layer with a grain size of 20 to 50 nm was obtained on the uranium surface, which acted as a barrier and prevented the further diffusion of anions into the matrix. The corrosion products of the UN0.35, UN0.75, and UN1.08 samples were mainly UO2-xNy and UO2 after reaction with the water vapor. The contents of UO2-xNy increased with increasing nitrogen contents, and the corrosion rate decreased significantly. The intermediate compounds UO2-xNy reacted slowly with the water vapor, and eventually converted to UO2. Meanwhile, the corrosion products of the UN1.5 sample were mainly U2N3+xOy and UO2-xNy after reaction with the water vapor. The percentage of U2N3+xOy and UO2-xNy remained almost stable over a long period of time, which indicated that the high contents of U2N3+xOy and UO2-xNy prolonged the time for complete conversion to UO2. It can be concluded that the U-N-O ternary compounds retarded the corrosion process and the UNx layers with high nitrogen contents showed excellent corrosion resistance.

Thermoelectric Chalcostibite: Solid-State Synthesis and Thermal Properties

In this study, thermoelectric chalcostibite (CuSbS<sub>2</sub>) compounds were fabricated using mechanical alloying (MA) and hot pressing (HP), and phase identification, microstructural observation, and thermal analysis were conducted. The thermal properties were then measured and compared with those of other Cu–Sb–S ternary compounds synthesized by the same solid-state process, namely, skinnerite (Cu<sub>3</sub>SbS<sub>3</sub>), famatinite (Cu<sub>3</sub>SbS<sub>4</sub>), and tetrahedrite (Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub>). Both the MA powder and HP-sintered samples contained a single-phase chalcostibite with an orthorhombic structure, and relative densities of 94.6–99.7% were obtained based on HP temperature. The full width at half maximum of the X-ray diffraction peak was significantly reduced for the HP specimens compared to that of the MA powder due to stress relaxation and grain growth during HP at elevated temperatures. However, practically no changes were observed in the lattice constants based on HP temperature. Differential scanning calorimetric analysis revealed that one endothermic reaction occurred at 814–815 K for the MA powder and at 818–821 K for the HP specimen, which were interpreted as the melting points of chalcostibite. Densely sintered compacts with densities close to the theoretical density were obtained using HP at temperatures of 623 K or higher. The constituent elements of the chalcostibites were uniformly distributed. As the HP temperature increased, thermal diffusivity and conductivity increased, but they decreased significantly as the measurement temperature increased. For the chalcostibite specimen hot-pressed at 623 K, the thermal diffusivity and conductivity were (0.75–0.36) × 10<sup>-2</sup> cm<sup>2</sup> s<sup>-1</sup> and 1.47–0.72 W m<sup>-1</sup> K<sup>-1</sup> at 323–623 K, respectively. Compared with other Cu–Sb–S ternary compounds, the thermal diffusivity was higher at low temperatures but similar at high temperatures, and the thermal conductivity above 500 K was lower than 1 W m<sup>-1</sup> K<sup>-1</sup>.

Ternary Nanocomposites of Copper/graphitic‐Phase Carbon Nitride/rare‐Earth Pentaborate for Photocatalytic Applications Under Simulated Sunlight Illumination

AbstractA wide variety of borate materials are emerging as photocatalysts. Usually, the borates possess a large bandgap which limits their absorption of visible light, and the strategy of preparing nanocomposites is an effective way to enhance the absorption of light. X‐ray powder diffraction, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to show that a three‐component nanocomposites was successfully prepared. For the photo‐degraded reactions of rhodamine B(RhB) and doxycycline hydrochloride(DH), the optimum composition of the ternary composite is a molar ratio of Gd0.9Ce0.1B5O9(GCBO) and g‐C3N4(CN) of 7 : 93, besides the mass of Cu is 2 % of the sum of the above two masses, and the ternary composite is abbreviated as 2Cu/CN@GCBO‐7. The kinetic constant for the photodegradation of RhB of sample 2Cu/CN@GCBO‐7 is 0.0580 min−1, which is 3.6 and 3.8 times that of non‐composite CN and GCBO. The mechanism postulated by free radical quenching experiments suggests that the importance of the three radicals is hole >⋅OH>⋅O2− in the photodegradation reaction. In addition, the kinetic constant for the photodegradation of DH of sample 2Cu/CN@GCBO‐7 is 0.0018 min−1, and the sample 2Cu/CN@GCBO‐7 has a hydrogen evolution rate of 11.8 μmol/h/g.

Fabrication and Characterization of Photocatalyst Pb3CdO7 for Degradation of Azure-A

Present work comprises of fabrication of the novel Pb3CdO7 ternary oxide composite from the corresponding precursors using a co-precipitation approach and calcined. The as-prepared material is then characterized by FTIR, FE-SEM, XPS, EDX, XRD, HR-TEM etc. analytical methods. Based on UV-Vis-NIR spectroscopy, the composite's direct energy band gap is determined to be 5.23 eV, which makes it an effective photocatalyst. The prepared photocatalyst is found to degrade Azure-A dye with an efficiency of up to 94.87%. Scavenger study suggests the participation of active free radicals O2•- (superoxide anion radical) as the responsible species in breakdown of the dye molecules. The operating parameters are controlled to maximize the photodegradation and a kinetic study is carried out. Used photocatalyst is recycled and is found to work at the same pace for up to five cycles.

Ternary intermetallic compounds R23Ru7In4 (R[dbnd]Ce, Pr): Synthesis, crystal structure and physical properties

Two novel ternary intermetallic compounds Ce23Ru7In4 and Pr23Ru7In4 were synthesized by arc melting of components and subsequent annealing at 600 °C. Both compounds crystallize in a hexagonal cell, with structure type Pr23Ir7Mg4, space group P63mc (№ 186), Pearson symbol hP68, Z = 2, the cell parameters: a = 9.861(5) Å, c = 22.520(12) Å (Ce); a = 9.9260(7) Å, c = 22.4109(2) Å (Pr). The structure of Ce23Ru7In4 was determined by single-crystal X-ray diffraction and the structure of Pr23Ru7In4 was determined by the Rietveld method using powder X-ray diffraction pattern. Compound Ce23Ru7+xIn4-x exist in the homogeneity range 0 ≤ x ≤ 3. An essential feature of compound Ce23Ru7In4 is the presence of abnormally short distances Ce–Ru (2.637 Å, 2.735 Å). The compound Pr23Ru7In4 melts incongruently and compound Ce23Ru7In4 melts congruently at temperatures 756 and 683°С respectively. The Pr23Ru7In4 compound is characterized by the presence of a magnetic transition at 12 K. The observed magnetic transition is most likely indicative of a transition to the spin glass state.

Ternary particle composite synergistically enhances the fluidity and dielectric properties of filled thermal conductive epoxy resin

Abstract Particle-packed epoxy materials are widely used to improve the thermal conductivity of insulation materials. However, the addition of fillers increases the viscosity of the composite which reduces its operability, and is not conducive to the packaging of power electronic equipment such as electric transformers and reactors. Multi-scale particle compounding is one of the effective methods to enhance the co-processing performance of materials by reducing the friction between particles and epoxy matrix while forming an effective thermal conductivity network. Three types of spherical alumina sized around 4 μm, 38 μm, and 125 μm were used as fillers to study the fluidity, thermal conductivity, and dielectric properties of single-filled and ternary compounds. The results showed that the ternary particle composite reduced the viscosity of the precursor by up to 68.8%, achieving a synergistic improvement in operability, thermal conductivity, and electrical performance.

On the U-Fe-C Isothermal Section at 1100 °C

The energy crisis and climate change have promoted a growing interest in non-fossil sources, such as nuclear, with uranium carbides being seen as potential fuel candidates for Generation IV nuclear reactors. However, the need of accurate thermophysical data for the fuel and its compatibility with core materials during the extreme fission conditions is still an issue. Here a study of the ternary uranium-iron-carbon system performed at 1100 °C using powder x-ray diffraction and Scanning Electron Microscopy coupled with Energy Dispersive Spectrometry is presented. The U-Fe-C isothermal section is characterized by two ternary compounds, thirteen 3-phase regions and five 2-phase regions. UFeC2 and ~ U11Fe12C18 were confirmed to be present at 1100 °C and crystallize in structures related to the binary uranium carbides. UFeC2 crystallizes in an original structure type, a distorted variant of the UCoC2 structure, with space group P4/n and a = 3.503(5) Å and c = 7.405(5) Å lattice parameters. ~ U11Fe12C18, has a crystal structure related to the Th11Ru12C18 structure-type (space group I4¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{4 }$$\\end{document}3m) with the lattice parameter a ≈ 10 Å. Furthermore, an island of a α-UC2-based phase with 32U:4Fe:64C composition was found in the 1100 °C isothermal section, indicating the inclusion of Fe in the α-UC2 binary compound.

Spectral properties of Yb-doped AgBiS2 and AgInS2 nanocrystals

Subject of study. The spectral features of nanocrystals with ternary compositions I-V-VI2 and I-III-VI2 doped with the rare earth metal ytterbium are investigated and described. Purpose of the study. The aim of this work is to develop a novel synthesis method for these nanocrystals to further examine their optical and morphological properties. Method. The average sizes of AgInS2:Yb and AgBiS2:Yb nanocrystals are analyzed using atomic force microscopy and dynamic light scattering, and the results are compared. Spectrophotometry and spectrofluorimetry are employed to record the absorption and photoluminescence spectra, respectively. Additionally, the photoluminescence decay kinetics are recorded using a laser scanning luminescence microscope for a deeper exploration of the electronic structure of the synthesized materials. Main results. Morphological analysis reveals that single-stage synthesis produced nanocrystals based on the AgInS2 matrix are smaller than the reference sample, while two-stage synthesis results in average nanocrystal sizes 1.5 times larger than the reference sample. The absorption spectra of the AgInS2:Yb and AgBiS2:Yb samples, as well as their reference samples, correspond to typical absorption spectra of semiconductor nanocrystals of ternary compounds. The absorption spectrum of AgBiS2:Yb nanocrystals, unlike AgInS2:Yb, spans a broad range from 300 nm to 1300 nm. In the photoluminescence spectra of AgInS2 and AgInS2:Yb nanocrystals, no significant shift of the band maximum is observed, and photoluminescence typical of Yb ions is absent. It is found that the weighted average photoluminescence lifetime in AgInS2:Yb nanocrystals can be modulated by ytterbium doping. Photoluminescence in AgBiS2 and AgBiS2:Yb samples is not detected in the red and near-infrared regions. Practical significance. These materials may be used in the fabrication of absorber layers for solar cells, as well as sensitizers for photodynamic and photothermal therapy. Further studies of isotropic samples of these nanocrystals could not only expand their potential applications but also enhance the physical properties of nanoparticles in the long term.

Suppression of bipolar diffusion effect on layered anisotropic PbBi4Te7 thermoelectric material via Se alloying

The unique layered structure and intrinsically low lattice thermal conductivity of ternary compound PbBi4Te7 have rendered it a promising thermoelectric material. However, the bipolar diffusion effect induced by inherent excitation results in deteriorated Seebeck coefficients and amplified thermal conductivity. In this study, the bipolar diffusion effect of PbBi4Te7 is effectively suppressed through enlarging the bandgap via Se alloying, thereby facilitating its potential application as a complementary counterpart to p-type materials. A maximum ZT value of ∼0.67 is achieved in PbBi4(Te0.7Se0.3)7 at 723 K, signifying an impressive improvement of 121 % compared to pure PbBi4Te7. This study provides a novel insight into enhancing the thermoelectric performance of ternary materials.

Preparation and properties of CdS0.25Se0.75/N-GQDs/3D rGO ternary composites

Preparation and properties of CdS0.25Se0.75/N-GQDs/3D rGO ternary composites

Enhancing the CO2 adsorption with dual functionalized coconut shell-hydrochar using Chlorella microalgae and metal oxide: Synthesis, physicochemical properties & mechanism evaluations

This study aims to develop an inexpensive, environmentally-friendly adsorbent for capturing CO2 using coconut shells, widely abundant in Asian agricultural waste. The raw coconut shell adsorbent (CS) has undergone dual functionalization utilizing Chlorella microalgae and magnesium oxide (MgO) to enhance its physicochemical properties. Through dual functionalization, minimizing the loss of surface area and reducing the temperature sensitivity often occurring during CO2 adsorption is possible. The surface morphology, functional groups, and thermochemical properties of CS-hydrochar were characterized and evaluated. The characterization demonstrates the successful development of the ternary composite (HCS-A-Mg), with a specific surface area of 1045 m2/g and containing nitrogen and metal oxide functional groups. XRD analysis of HCS-A-Mg reveals crystalline peaks at 36.8°, 42.9°, and 63°, confirming the successful impregnation of MgO. The adsorption result showed that HCS-A-Mg exhibits a higher CO2 adsorption capacity of 2.63 mmol/g, 50% higher than pristine hydrochar (HCS). The adsorption study revealed that the CO2 adsorption capacity of HCS-A-Mg can be maximized to 3.23 mmol/g at 101 °C and 4.6 bar. Adsorption isotherms shows that the non-linear Sips model best describes the adsorption process, indicating a multilayer adsorption mechanism with profound surface heterogeneity of n = 2.3 for HCS-A-Mg, signifying higher accessibility of gas molecules deep into pores, enabling a variety of adsorption sites for CO2 binding. Selectivity and reusability studies were conducted to validate the adsorbent applicability for industrial applications. HCS-A-Mg has higher CO2/N2 selectivity by 41–57% and 0.05% loss of adsorption capacity after the 10th cyclic operation, suggesting their suitability for industrial applications. This finding underscores the potential of microalgae and magnesium oxide in advancing carbon capture technology and addressing environmental challenges.

Influence of graphitic phase on the structural, optical, electrical and photocatalytic properties of BiFeO3/KNbO3 based binary nanocomposites

Synthesis of ternary nanocomposites of BiFeO3-Graphene-KNbO3 through simple solution method has been made at various concentrations of graphene ranging 0.025–0.1 % mole fraction. The obtained nanocomposite powders with varying content of graphitic phase were subjected to different characterization techniques such as XRD, Raman, SEM/EDX/Elemental mapping, HR-TEM, UV–Vis–NIR spectroscopy, dielectric and photodegradation measurements. All above studies have provided the collective impression of the existence of all entities in the prepared ternary composites. Dielectric studies revealed that progressive loading of graphene content led to the increased pathway for the conduction of electrons in the sample. However, the loading of graphene at appropriate concentration has brought out increased dye degradation capacity of BiFeO3-Graphene-KNbO3 ternary nanocomposites towards methylene blue dye. The results obtained from various studies have been discussed in detail.

Active learning of ternary alloy structures and energies

Machine learning models with uncertainty quantification have recently emerged as attractive tools to accelerate the navigation of catalyst design spaces in a data-efficient manner. Here, we combine active learning with a dropout graph convolutional network (dGCN) as a surrogate model to explore the complex materials space of high-entropy alloys (HEAs). We train the dGCN on the formation energies of disordered binary alloy structures in the Pd-Pt-Sn ternary alloy system and improve predictions on ternary structures by performing reduced optimization of the formation free energy, the target property that determines HEA stability, over ensembles of ternary structures constructed based on two coordinate systems: (a) a physics-informed ternary composition space, and (b) data-driven coordinates discovered by the Diffusion Maps manifold learning scheme. Both reduced optimization techniques improve predictions of the formation free energy in the ternary alloy space with a significantly reduced number of DFT calculations compared to a high-fidelity model. The physics-based scheme converges to the target property in a manner akin to a depth-first strategy, whereas the data-driven scheme appears more akin to a breadth-first approach. Both sampling schemes, coupled with our acquisition function, successfully exploit a database of DFT-calculated binary alloy structures and energies, augmented with a relatively small number of ternary alloy calculations, to identify stable ternary HEA compositions and structures. This generalized framework can be extended to incorporate more complex bulk and surface structural motifs, and the results demonstrate that significant dimensionality reduction is possible in thermodynamic sampling problems when suitable active learning schemes are employed.

Effect of lignin on the structure-property behavior of metal-coordinated and chemically crosslinked ethylene-propylene-diene-monomer composites

The efficient development and utilization of green biomass-based macromolecule engineering materials are essential for the sustainable development of human civilization. In this study, lignin-based ethylene-propylene-diene-monomer (EPDM) composites with excellent mechanical performance were fabricated using a simple method. The effects of water-insoluble enzymatically hydrolyzed lignin (EL) and alkali lignin (KL) on the mechanical performance of the composites were investigated separately. The results showed that the tensile strength of EPDM reinforced with KL and EL increased to 24.5 MPa and 22.1 MPa, respectively, surpassing that of the carbon black (CB)-reinforced EPDM. After 72 h of thermo-oxidative aging, the retention rates of the tensile strength and elongation at break in the lignin-reinforced EPDM were much better than those formed with pure CB, indicating that lignin significantly improved the thermo-oxidative aging resistance of the composites. In summary, the Zn2+ coordination bonds formed between the interface of EPDM and lignin in lignin/CB/EPDM ternary composites effectively improved the mechanical performance and aging resistance of the composites. This study has significant implications for enhancing the utilization of lignin and green functional polymer materials.

Development of Sustainable 3D Printable Ternary Composite

3D printing technology has the potential to reduce construction waste through its controlled manufacturing process and optimized material consumption, making it a promising sustainable construction approach with reduced environmental impact. However, current 3D printed structures often have a high carbon footprint due to the large amounts of fine-grained primary materials used in mortar composites. Most efforts to develop 3D printed structures are associated with concrete and Portland cement-based materials.This research presents an innovative approach for the reuse of gypsum to develop a material suitable for 3D printing, with the goal to industrialize the usage of waste gypsum in civil engineering. The objective of this study is to develop a sustainable gypsum-cement-pozzolanic (GCP) ternary binder composite, incorporating recycled industrial waste gypsum materials such as construction demolition waste gypsum (CDG), along with Portland cement and secondary pozzolanic materials. The GCP ternary composite combines the desired properties of gypsum, such as fast setting time, with those of Portland cement, which offers high final strength. The addition of a pozzolanic component is essential to ensure the chemical stability of this ternary system.As part of this study, ternary composites were designed and tested for their mechanical properties, durability, and suitability for 3D printing. Development and optimization of the ternary composite was carried out as a loop of procedures (Fig.1). Through these optimization procedures, a range of mixtures with necessary properties for 3D printing was found. To ensure sustainability and to assess the environmental impact of the mixtures, life cycle assessment (LCA) was performed.The LCA of GCP composites showed at least 1.5 times lower embodied energy and carbon dioxide emissions compared to Portland cement-based mortars. This is without considering avoided emissions from the end-of-life stage of gypsum waste, as well as higher technical properties that make GCP composites superior to regular cement composites. Considering these factors, GCP composites exhibit even lower emissions and are considered a viable alternative to Portland cement-based mortars.

Unusual superconductivity in crystallographically disordered RT2−xSn2 compounds

The discovery of new superconducting materials represents a complementary and crucial tile to shed light on the mechanism controlling the phenomenon of superconductivity. During the search for new superconducting materials, we discovered a new series of intermetallic compounds with the general composition RZn2−xSn2 (R = La, Ce, Pr, Nd). Their formation and crystal structure have been investigated. The Zn content decreases along the series from ≈ 1.50 in LaZn1.50(1)Sn1.98(2) to ≈ 1.32 in NdZn1.321(8)Sn2.01(2), due to the partial occupation of one of the two Zn sites [the Zn1 (2c) site, which from ≈ 50% in the La compound drops to ≈ 42%, ≈ 37% and ≈ 32% in the Ce, Pr and Nd compounds, respectively]. Both the Zn occupation factor and unit cell volume follow the lanthanide contraction. No such compound has been observed with Sm. AC and DC magnetic susceptibility and transport measurements revealed LaZn1.5Sn2 to undergo a sharp superconducting transition at Tc = 5.5 K. In order to search for further possible superconductive homologues, the lanthanum substituted phases La(Zn,T)2–xSn2 (T = Ti, Mn, Fe, Co, Ni, Cu, Pd, Ag, Pt, Au, Cd; x ≈ 0.5) were also prepared. The crystal structure of the ternary compounds is a disordered defective derivative of the tetragonal CaBe2Ge2-type (tP10, P4/nmm), with a partially occupied Zn Wyckoff site and a disordered Sn position. Three related isostructural series, corresponding to three new prototypes, have been identified; they all contain conventional checkered pyramidal layers characteristic of the archetype. The magnetic and transport properties have been measured for some of these substituted quaternary La compounds and we found that superconductivity is preserved in them but in the orthorhombic compounds or when T was a magnetic transition metal (e.g., Ni or Mn). A slight decrease in Tc down to about 4.0 K was detected as a result of the Zn by T atomic substitution.

Extraordinary Structural Reconstruction of Nanolaminated Ta2FeC MAX Phase for Enhanced Oxygen Evolution Performance.

Renewable energy technologies, such as water splitting, heavily depend on the oxygen evolution reaction (OER). Nanolaminated ternary compounds, referred to as MAX phases, show great promise for creating efficient electrocatalysts for OER. However, their limited intrinsic oxidative resistance hinders the utilization of conductivity in Mn+1Xn layers, leading to reduced activity. In this study, a method is proposed to improve the poor inoxidizability of MAX phases by carefully adjusting the elemental composition between Mn+1Xn layers and single-atom-thick A layers. The resulting Ta2FeC catalyst demonstrates superior performance compared to conventional Fe/C-based catalysts with a remarkable record-low overpotential of 247mV (@10mA cm-2) and sustained activity for over 240h. Notably, during OER processing, the single-atom-thick Fe layer undergoes self-reconstruction and enrichment from the interior of the Ta2FeC MAX phase toward its surface, forming a Ta2FeC@Ta2C@FeOOH heterostructure. Through density functional theory (DFT) calculations, this study has found that the incorporation of Ta2FeC@Ta2C not only enhances the conductivity of FeOOH but also reduces the covalency of Fe─O bonds, thus alleviating the oxidation of Fe3+ and O2-. This implies that the Ta2FeC@Ta2C@FeOOH heterostructure experiences less lattice oxygen loss during the OER process compared to pure FeOOH, leading to significantly improved stability. These results highlight promising avenues for further exploration of MAX phases by strategically engineering M- and A-site engineering through multi-metal substitution, to develop M2AX@M2X@AOOH-based catalysts for oxygen evolution.

Borides Mn3-x{Rh,Ir}5B2 with Ti3Co5B2-type: X-ray single crystal and TEM data, physical properties

A cursory investigation of the phase relations in the Mn-{Rh,Ir}-B systems prompted for each system a ternary compound, Mn3-x{Rh,Ir}5B2, the crystal structure of them was determined from X-ray single crystal data to be isotypic with the Ti3Co5B2-type (space group P4/mbm, No. 127). In both cases the Mn-site in 2a at the origin of the unit cell exhibits a significant defect (or Mn/B substitution). Transmission electron microscopy studies confirm the absence of a superstructure related to these defects/disorder. The two phases, Mn3-xRh5B2 (x∼0.34) and Mn3-xIr5B2 (x∼0.85) at 950 °C show rather limited homogeneity regions pointing towards higher Mn-contents. Whereas temperature dependent magnetization and specific heat measurements of Mn2.15Ir5B2 do not reveal any indication for a magnetic phase transition in the temperature range from 3 to 300 K, a broad specific heat anomaly at around 200 K and a tilde shape of the temperature dependent magnetization of Mn2.66Rh5B2 appears indicative of an antiferromagnetic phase transition. The latter is also reflected by an anomaly of the electrical resistivity (ρ; 4–300 K) of Mn2.66Rh5B2 which displays a non-monotonous temperature dependence, whereas ρ(T) of Mn2.15Ir5B2 displays a simple metallic-like behavior dominated by scattering from defects. Elastic moduli and Poisson's ratio were determined at room temperature from Resonant Ultrasonic Spectroscopy (RUS) data yielding Young's moduli of E ∼ 170 GPa for Mn2.66Rh5B2 and E ∼ 210 GPa for Mn2.15Ir5B2. Vickers hardness HV is lower for Mn2.66Rh5B2 (HV = 590 ≅ 5.79 GPa) than for Mn2.15Ir5B2 (HV = 655 ≅ 6.42 GPa). The indentation fracture toughness for Mn2.15Ir5B2 was IKC = 0.71 ± 0.5 MPa m1/2.

Surface Segregation Studies in Ternary Noble Metal Alloys: Comparing DFT and Machine Learning with Experimental Data.

Surface segregation, whereby the surface composition of an alloy differs systematically from the bulk, has historically been hard to study, because it requires experimental and modeling methods that span alloy composition space. In this work, we study surface segregation in catalytically relevant noble and platinum-group metal alloys with a focus on three ternary systems: AgAuCu, AuCuPd, and CuPdPt. We develop a data set of 2478 fcc slabs with those compositions including all three low-index crystallographic orientations relaxed with Density Functional Theory using the PBEsol functional with D3 dispersion corrections. We fine-tune a machine learning model on this data and use the model in a series of 1800 Monte Carlo simulations spanning ternary composition space for each surface orientation and ternary chemical system. The results of these simulations are validated against prior experimental surface segregation data collected using composition spread alloy films for AgAuCu and AuCuPd. Our findings reveal that simulations conducted using the (110) orientation most closely match experimentally observed surface segregation trends, and while predicted trends qualitatively match observation, biases in the PBEsol functional limit numeric accuracy. This study advances understanding of surface segregation and the utility of computational studies and highlights the need for further improvements in simulation accuracy.

Mitigating phase changes in the gas-phase that disrupt CO2 capture in membrane contactors: CO2-NH3-H2O as a model ternary system

Solid and liquid products can form in the gas phase of membrane contactors applied to reactive ternary systems for CO2 absorption, which poses a critical barrier for carbon capture applications. The mechanism initiating these unwanted phase changes in the gas phase is unclear. This study therefore systematically characterises CO2 absorption in distinct regions of the vapour-liquid equilibrium (VLE) within an illustrative ternary system (CO2-NH3-H2O), to provide an explanation for the formation and mitigation of these solid and liquid products in the gas-phase. Unstable CO2 absorption and increased pressure drop indicated product formation within the gas-phase, which occurred at high CO2 capture ratios. Temporal analysis of gas-phase composition enabled gas-phase products to be related to the relative ternary composition. This was subsequently correlated to distinct regions of the VLE. Consequently, mitigation strategies can be developed with recognition for where products are least likely to form. Pressurisation was proposed to modify the relative gas-phase ammonia composition to reposition conditions within the VLE. The commensurate increase of CO2 into the solvent shifts the ammonia-ammonium equilibrium towards ammonium to indirectly reduce vapour pressure. This synergistic strategy allows sustained operation of membrane contactors for CO2 separation within reactive ternary systems which are critical to delivering carbon capture economically at scale.