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2019-01-14
Tight-binding calculations of SiGe alloy nanocrystals in SiO2 matrix
In the empirical tight-binding approach we study the electronic states in spherical SiGe nanocrystals embedded in SiO2 matrix. The energy and valley structure is obtained as a function of Ge composition and nanocrystal size. The calculations show that the mixing of hot electrons in the nanocrystal with electrons in wid...
1901.04271v1
2019-03-31
Application of Cluster Variation and Path Probability Methods to the Tetragonal-Cubic Phase Transition in ZrO2
Cluster variation method (CVM) and path probability method (PPM) have generally been employed to study replacive phase transitions in alloy systems. Recently, displacive phase transitions have been explored within the realm of replacive phase transition in the CVM theoretical framework by viewing displaced atoms as dif...
1904.00407v1
2019-04-01
Property-aimed embedding: a machine learning framework for material discovery
Proposing new materials by atom substitution based on periodic table similarity is a conventional strategy of searching for materials with desired property. We introduce a machine learning frame work that promotes this paradigm to be property-specific and quantitative. It is of peculiar usefulness in situations where a...
1904.08750v1
2019-07-22
Material development towards a solid 100 kW electron-gamma converter for TRIUMF-ARIEL
A series of irradiation tests have been performed at TRIUMF to investigate different material pairings to act as high-power electron-to-gamma converter for the ARIEL Electron Target East (AETE). The bulk of the converter body will be made out of an aluminum alloy with a sub-millimeter high-Z metal layer bonded to the s...
1907.09363v1
2019-07-29
Relativistic stable processes in quasi-ballistic heat conduction in thin film semiconductors
In this article, we show how relativistic alpha stable processes can be used to explain quasi-ballistic heat conduction in semiconductors. This is a method that can fit experimental results of ultrafast laser heating in alloys. It also provides a connection to a rich literature on Feynman-Kac formalism and random proce...
1907.12676v1
2019-10-01
Superconductivity in Nb5Ir3-xPtxO
We have investigated the superconducting critical temperature Tc of solid solution Nb5Ir3-xPtxO with the Ti5Ga4-type structure. The both end-members of Nb5Ir3O and Nb5Pt3O are reported to be superconductors with Tc of 10.5 K and 3.8 K, respectively. Particularly Nb5Ir3O is considered as a two-gap superconductor. The en...
1910.00686v1
2019-10-25
Anisotropic exchange in GdGa
In this work we discuss the non-collinear ground-state reported for GdGa on the basis of a model Hamiltonian considering anisotropic exchange interactions. We show that a competition between intra and inter-sublattice exchange interactions can lead to a canted structure, which competes with a collinear (ferro or antife...
1910.11833v1
2012-09-27
Vertex corrections to the mean-field electrical conductivity in strongly disordered electron systems
Mean-field theory of non-interacting disordered electron systems is widely and successfully used to describe equilibrium properties of alloys in the whole range of disorder strengths. It, however, fails to take into account effects of quantum coherence and localizing back-scattering effects when applied to transport ph...
1209.6128v1
2014-06-04
Multiaxial Fatigue Behaviour of A356-T6
Aluminum alloy A356-T6 was subjected to fully reversed cyclic loading under tension, torsion and combined loading. Results indicate that endurance limits are governed by maximum principal stress. Fractography demonstrates long shear mode III propagation with multiple initiation sites under torsion. Under other loadings...
1406.1204v1
2018-02-28
High-entropy ceramic thin films; A case study on transition metal diborides
High-entropy materials often outperform their lower-entropy relatives in various aspects, such as thermal stability and fracture toughness. While there are extensive research activities in the field of high-entropy alloys, comparably little is performed for high-entropy ceramics, and especially for high-entropy diborid...
1802.10260v1
2018-12-06
Identity Ordering and Metastable Clusters in Fluids with Random Interactions
We use Langevin dynamics simulations to study dense two-dimensional systems of particles where all binary interactions are different (AID) in the sense that each interaction parameter is characterized by a randomly chosen number. We compare two systems that differ by the probability distributions from which the interac...
1812.02620v1
2018-12-13
Mechanical properties of electrodeposited amorphous/crystalline multilayer structures in the Fe-P system
Amorphous/crystalline multilayer structures of Fe-P alloys were deposited electrochemically using the single bath technique. Hall-Petch behavior of microhardness with respect to sublayer thickness was observed down to a sublayer thickness of 15 nm. For thinner sublayers, a hardness plateau was obtained. The transition ...
1812.05404v1
2019-02-13
Advances in the optimization of silicon-based thermoelectrics: a theory perspective
Thermoelectric devices convert temperature gradients into electrical power and vice versa, thus enabling energy scavenging from waste heat, sensing and cooling. Yet, many of these attractive applications are hindered by the limited efficiency of thermoelectric materials, especially in the low temperature regime. This r...
1902.04695v1
2019-06-04
Standard-Based EBSD: Fingerprinting of Order and Orientation in Materials
Orientation determination does not necessarily require complete knowledge of the local atomic arrangement in a material. We present a method for microstructural phase discrimination and orientation analysis of phases for which there is only limited information available. In this method, experimental Kikuchi diffraction...
1906.01717v1
2020-04-09
Surface Crystallization of Monoatomic Pd Metallic Glasses
Crystallization from an amorphous atomic structure is usually seen as a spontaneous process in pursuit of a lower energy state, but for alloy systems it is often hard to elucidate because of the intrinsic structural and compositional complexity. Here, by means of electron beam irradiation, we found surface-limited, and...
2004.04316v1
2020-08-05
Impact of Scattering on Phonon Behavior of Alloys
The lattice dynamics of Cu3Au, Ni70Pt30, Pd90Fe10, and Pd96Fe04 intermetallic is studied using the DFT calculations. We calculated the phonon dispersions and phonon densities of states along two high symmetry paths of the Brillouin zone by Weighted Dynamical Matrix (WDM) approach. We also compared the results with the ...
2008.02652v3
2020-08-21
Multifunctional properties of composition graded Al wires
The potentiality of composition graded AlMgSi wires for optimized combination of electrical conductivity and torsion strength has been investigated. Composition graded wires were obtained by co-drawing commercially pure Al with an AlMgSi alloy followed by diffusion annealing. Diffusion gradients and local hardening res...
2008.09431v1
2021-03-12
Structural defects responsible for strain glassy transition in Ni$_{50+x}$Ti$_{50-x}$
The strain glassy phase is produced by doping a small percentage of impurity in a martensitic alloy. Its ground state is conceived to consist of martensitic nano domains spatially separated from each other by a defect phase. The present study, by probing the local structure around the Ni and Ti in martensitic and strai...
2103.07103v1
2022-03-03
Restructuring in bimetallic core-shell nanoparticles: Real time observation
The formation process of core-shell bimetallic nanoparticles synthesized by sputtering onto a substrate is observed in real time using an originally developed acoustic technique. The technique enables us to evaluate the structural change of nanoparticles at room temperature without contacting the nanoparticles or subst...
2203.01512v1
2016-12-12
Effect of secondary electron emission on subnanosecond breakdown in high-voltage pulse discharge
A subnanosecond breakdown in high-voltage pulse discharge is studied in experiment and in kinetic simulations for mid-high pressure in helium. It is shown that the characteristic time of the current growth can be controlled by the secondary electron emission. We test the influence of secondary electron yield on plasma ...
1612.03829v1
2016-12-16
Typical-medium, multiple-scattering theory for disordered systems with Anderson localization
The typical medium dynamical cluster approximation (TMDCA) is reformulated in the language of multiple scattering theory to make possible first principles calculations of the electronic structure of substitutionally disordered alloys including the effect of Anderson localization. The TMDCA allows for a systematic inclu...
1612.05611v1
2017-02-08
Aging effects of dodecagonal quasicrystal formed in Mn-Cr-Ni-Si alloys
The formation of Mn-Cr-Ni-Si dodecagonal quasicrystal has been studied at 600 and 700 C. The growth process of the quasicrystal from as-cast beta-Mn phase was explained by Johnson-Mehl-Avrami equation. In order to evaluate structural quality of the quasicrystal, distortion in the diffraction pattern observed along the ...
1702.02266v1
2017-02-08
Temperature-dependent phonon spectra of magnetic random solid solutions
A first-principles-based method for computing phonons of magnetic random solid solutions including thermal magnetic fluctuations is developed. The method takes fluctuations of force constants (FCs) due to magnetic excitations as well as due to chemical disorder into account. The developed approach correctly predicts th...
1702.02389v1
2017-06-27
Seebeck Effect in Nanomagnets
We present a theory of the Seebeck effect in nanomagnets with dimensions smaller than the spin diffusion length, showing that the spin accumulation generated by a temperature gradient strongly affects the thermopower. We also identify a correction arising from the transverse temperature gradient induced by the anomalou...
1706.08753v2
2017-10-03
Liquid metals: early contributions and some recent developments
We illustrate in this contribution the progress in the theoretical study of liquid metals made in the last decades, starting from the example of liquid gallium and the early work in Jean-Pierre Badiali's group. This was based on the combination of the perturbation theory with pseudo-potentials for the electrons and the...
1710.01092v1
2017-10-25
Ordered C vacancies in titanium carbides: a correlation between crystal structure and the effects on oxidation behavior at elevated temperature
It has been widely accepted that the introduction of titanium carbides into titanium-based alloys can significantly enhance the oxidation resistance due to their superior physicochemical stability at elevated temperatures. The present study reported for the first time that the ordered C vacancies within titanium carbid...
1710.09311v1
2018-04-10
Amorphous complexions enable a new region of high temperature stability in nanocrystalline Ni-W
Solute segregation is used to limit grain growth in nanocrystalline metals, but this stabilization often breaks down at high temperatures. Amorphous intergranular films can form in certain alloys at sufficiently high temperatures, providing a possible alternative route to lower grain boundary energy and therefore limit...
1804.03291v2
2018-04-12
Dislocation-assisted linear complexion formation driven by segregation
Atomistic simulations are used to study linear complexion formation at dislocations in a body-centered cubic Fe-Ni alloy. Driven by Ni segregation, precipitation of the metastable B2-FeNi and stable L10-FeNi phases occurs along the compression side of edge dislocations. If the Ni segregation is not intense enough to en...
1804.04302v2
2018-04-17
Composition dependence of radiation induced patterns in non miscible alloys
We present a theoretical approach exhaustively predicting the variety of steady-state shapes emerging under irradiation in thermodynamically unstable binary mixtures. We show that stripes or honeycomb structures are controlled not only by the two classical irradiation parameters: the irradiation flux and the temperatur...
1804.06222v1
2019-03-08
Ti surface modification for biomedical applications
Micro Arc Oxidation (MAO) is an electrochemical approach for the surface treatment usually applied on so called valve metals such as Al, Mg and Ti. MAO is usually carried out an aqueous electrolyte, which involves a bath cooling and leads to the creation of surface contained components originated in the electrolyte. In...
1903.03507v1
2019-03-12
Vacuum balloon -- a 350-year-old dream
The centuries-old idea of a lighter-than-air vacuum balloon has not materialized yet as such structure needs to be both light enough to float in the air and strong enough to withstand atmospheric pressure. We propose a design of a rigid spherical sandwich shell and demonstrate that it can satisfy these stringent condit...
1903.05171v3
2019-05-06
Computation of topological phase diagram of disordered Pb$_{1-x}$Sn$_{x}$Te using the kernel polynomial method
We present an algorithm to determine topological invariants of inhomogeneous systems, such as alloys, disordered crystals, or amorphous systems. Based on the kernel polynomial method, our algorithm allows us to study samples with more than $10^7$ degrees of freedom. Our method enables the study of large complex compoun...
1905.02215v2
2019-09-24
3D aspects of materials design for metals and alloys
Nowadays, most structural integrity concepts rely on simplified isotropic ma-terial data that are used within continuum mechanics modeling approaches. In contrast, modern casting and forming processes yield complex microstruc-tures coming along with pronounced gradients in the material's properties in various length sc...
1909.13797v1
2019-12-05
Micromagnetic Modeling of the Magnetization Behavior of NiMnGa FMSMAs
The model calculations of the magnetization curves for the internally twinned NiMnGa ferromagnetic shape memory alloy are performed at the different volume fractions of twin variants. The method is based on the direct minimization of our new micromagnetic free energy model of FMSMAs taking into account both the magneti...
1912.02495v1
2020-02-08
Atomic diffusion in alpha-iron across the Curie point: an effcient and transferable ab-initio-based modelling approach
An accurate prediction of atomic diffusion in Fe alloys is challenging due to thermal magnetic excitations and magnetic transitions. We propose an effcient approach to address these properties via Monte Carlo simulation, using ab-initio based effective interaction models. The temperature evolution of self- and Cu diffu...
2002.03126v2
2020-03-09
Energy scaling laws for geometrically linear elasticity models for microstructures in shape memory alloys
We consider a singularly-perturbed two-well problem in the context of planar geometrically linear elasticity to model a rectangular martensitic nucleus in an austenitic matrix. We derive the scaling regimes for the minimal energy in terms of the problem parameters, which represent the {shape} of the nucleus, the quotie...
2003.04095v1
2020-06-20
Can an amorphous crystallize into a high entropy alloy?
On the premise that amorphous-HEA composites could demonstrate high toughness and resistance to embrittlement akin to the phase separating glassy-solid solution composites, we develop a thermodynamics based approach to identify chemical compositions capable of undergoing the amorphous to HEA transformation. We introduc...
2006.11579v1
2020-05-15
Hybrid acousto-electromagnetic metamaterial superconductors
Recent theoretical and experimental studies demonstrated that an electromagnetic metamaterial approach is capable of drastically increasing the critical temperature Tc of composite metamaterial superconductors. This progress was achieved by engineering the frequency-dependent dielectric response function of the metamat...
2006.13671v1
2020-07-06
Interface evolution in phase transformation ruled by nucleation and growth
An analytical model for the evolution of the boundary of the new phase in transformations ruled by nucleation and growth is presented. Both homogeneous and heterogeneous nucleation have been considered: The former includes transformations in 2D and 3D space and the latter nucleation and growth on flat solid substrate. ...
2007.02700v1
2020-07-22
First principles investigation on anomalous lattice shrinkage of W alloyed rock salt GeTe
According to Vegard's law, larger radius atoms substitute for smaller atoms in a solid solution would enlarge the lattice parameters. However, by first-principles calculations, we have observed unusual lattice shrinkage when W replaces Ge in rock salt GeTe. We attribute this anomalous contract to the larger electronega...
2007.11251v1
2020-10-21
Evidence for direct and indirect gap in FeSi from electron tunneling spectroscopy
We report electron tunneling spectroscopy studies on single crystalline FeSi sample performed for the case of homogeneous tunnel junction contacts and for the case of counter electrodes made from Pt-Rh alloy. Our results reveal that while the tunneling spectroscopy in the configuration with Pt-Rh tip is preferably sens...
2010.10838v1
2020-11-27
Low-temperature phase transitions in some quaternary solid solutions of IV-VI semiconductors
Samples of PbS$_x$Se$_y$Te$_{1-x-y}$, Pb$_{1-x}$Sn$_x$Te$_{1-y}$Se$_y$, and Pb$_{1-x}$Sn$_x$Te$_{1-y}$S$_y$ quaternary solid solutions were investigated in the 4--200~K temperature range using electrical and X-ray methods. The regions where low-temperature phase transitions occur were established. It was shown that pha...
2011.13992v1
2020-12-01
Study of involution domain based interfaces in Ni-Ti-Cu Shape Memory Alloy
An algorithm was made to study the lattice correspondence involved in phase transformation from cubic B2 to monoclinic B19'. The method is based on studying the orientation matrices generated from EBSD data. Starting from the very fundamental, coordinate transformation matrices as well as the vector transformation matr...
2012.00373v2
2020-12-07
On the characterization of butterfly and multi-loop hysteresis behavior
While it is widely used to represent hysteresis phenomena with unidirectional-oriented loops, we study in this paper the use of Preisach operator for describing hysteresis behavior with multidirectional-oriented loops. This complex hysteresis behavior is commonly found in advanced materials, such as, shape-memory alloy...
2012.03605v1
2020-12-31
Friedel oscillations and helium bubble ordering in molybdenum
Helium ions implanted into metals can evolve into ordered bubbles isomorphic to the host lattice. Long-range elastic interaction is generally believed to drive the formation of bubble superlattice, but little is known about the thermodynamics at the very initial stage. Our first-principles calculations demonstrate that...
2012.15402v1
2021-01-25
A solution to the permalloy problem
We propose a solution to the longstanding permalloy problem$-$why the particular composition of permalloy, Fe$_{21.5}$Ni$_{78.5}$, achieves a dramatic drop in hysteresis, while its material constants show no obvious signal of this behavior. We use our recently developed coercivity tool to show that a delicate balance b...
2101.09857v1
2021-02-22
A review of modelling in ferrimagnetic spintronics
In this review we introduce computer modelling and simulation techniques which are used for ferrimagnetic materials. We focus on models where thermal effects are accounted for, atomistic spin dynamics and finite temperature macrospin approaches. We survey the literature of two of the most commonly modelled ferrimagnets...
2102.11004v1
2021-03-24
An Overview of Planar Flow Casting of Thin Metallic Glasses and its Relation to Slot Coating of Liquid Films
Planar flow casting (PFC) is a method that can be used to make thin, long, and wide metallic alloy foils by extruding molten liquid through a thin and wide nozzle and immediately quenching on a moving roller. The quenching rates are high enough that amorphous metallic glasses may be formed which have many desirable pro...
2104.09251v1
2021-05-10
High-pressure synthesis of boron-rich chalcogenides B12S and B12Se
Two boron-rich chalcogenides B12S and B12Se isostructural to {\alpha}-rhombohedral boron were synthesized by chemical reaction of the elements at high-pressure - high-temperature conditions. The crystal structures and stoichiometries of both compounds were confirmed by Rietveld refinement and elemental analysis. The ex...
2105.04450v1
2021-05-23
Ab initio investigation of impurity ferromagnetism in the Pd1-xFex alloys: concentration and position dependence
We present the ab initio results of the structural and magnetic properties of the Pd host matrix implanted with Fe solute atoms at various concentrations. By means of density functional theory we confirm that iron impurities are able to initialize significant magnetization of the Pd atoms, when the impurity consentatio...
2105.10918v1
2021-05-25
Investigation by STEM-EELS of helium density in nanobubbles formed in aged palladium tritides
3He nanobubbles created by radioactive decay of tritium in palladium tritide are investigated after several years of aging. Scanning Transmission Electron Microscopy Electron Energy-Loss Spectroscopy (STEM-EELS) has been used to measure helium density from the helium K-edge around 23 eV. Helium densities were found bet...
2105.11893v1
2021-06-17
Plasticity of an extra-strong nanocrystalline stainless steel controlled by the "dislocation-segregation'' interaction
We study three structurally different states of nanocrystalline 316 steel and show that the state, where boundaries containing excess concentration of alloying elements are combined with mobile dislocations in grain interiors, allows maintaining extraordinarily high strength and remarkably enhanced plasticity. Underlyi...
2106.09321v1
2021-08-16
Micro-structural characteristics and indentation behavior of Ce-Al-Ga alloys
The first report of phase separation in metallic glass has attracted significant attention due to their unique micro-structural variations of amorphous phases at different domain size. In the continuation of this the view is to understanding the genesis of phase separation in Ce based metallic glass. In this paper, we ...
2108.06906v1
2021-09-08
A hard open X-band RF accelerating structure made by two halves
High-gradient linacs of next generation require novel accelerating structures which are compact, robust and cost-effective. Dedicated research and development have been launched in the linear-collider community. This paper focuses on the technological developments directed to show the viability of novel welding techniq...
2109.03954v1
2021-09-28
Machine learning predictions of superalloy microstructure
Gaussian process regression machine learning with a physically-informed kernel is used to model the phase compositions of nickel-base superalloys. The model delivers good predictions for laboratory and commercial superalloys, with $R^2>0.8$ for all but two components of each of the $\gamma$ and $\gamma'$ phases, and $R...
2109.13762v1
2021-09-28
A robust and efficient line search for self-consistent field iterations
We propose a novel adaptive damping algorithm for the self-consistent field (SCF) iterations of Kohn-Sham density-functional theory, using a backtracking line search to automatically adjust the damping in each SCF step. This line search is based on a theoretically sound, accurate and inexpensive model for the energy as...
2109.14018v3
2021-11-12
Micromagnetic modeling of magnetization distribution caused by internal twin microstructure of NiMnGa ferromagnetic shape memory alloys
In our present publication we will continue studying the effects of the magnetostatic energy on the magnetization behavior of FMSMAs recently started in some our publications. Our method is based on the direct minimization of our new micromagnetic free energy model of FMSMAs taking into account both the magnetic anisot...
2111.06605v1
2021-12-03
Mass transport computations via correlation splitting and a law of total diffusion
Directly computing mass transport coefficients in stochastic models requires integrating over time the equilibrium correlations between atomic displacements. Here, we show how to accelerate the computations via \green{correlation splitting and conditioning, which statistically amounts to estimating the mass transport c...
2112.01978v1
2021-12-19
Relaxation shortcuts through boundary coupling
When a hot system cools down faster than an equivalent cold one, it exhibits the Mpemba Effect. This counterintuitive phenomenon was observed in several systems including water, magnetic alloys and polymers. In most experiments the system is coupled to the bath through its boundaries, but all theories so far assumed bu...
2112.10187v1
2022-01-17
Perpendicularly Polarized Spin Hall Effects Induced by Spin-Dependent Scattering in Ferromagnetic Metals
Spin currents in ferromagnets afford diverse functionalities. We evaluate the extrinsic spin Hall effects of magnetic impurity scattering in ferromagnetic metals. We show that spin-dependent scattering can provide a high spin current polarized perpendicularly to the magnetization direction and is a dominant mechanism i...
2201.06222v2
2022-01-18
Uniaxial polarization analysis of bulk ferromagnets: Theory and first experimental Results
Based on Brown's static equations of micromagnetics, we compute the uniaxial polarization of the scattered neutron beam of a bulk magnetic material. The theoretical expressions are compared to experimental data on a soft magnetic nanocrystalline alloy. The micromagnetic SANS theory provides a general framework for pola...
2201.06802v1
2022-04-14
Cohesive zone modelling of hydrogen assisted fatigue crack growth: the role of trapping
We investigate the influence of microstructural traps in hydrogen-assisted fatigue crack growth. To this end, a new formulation combining multi-trap stress-assisted diffusion, mechanism-based strain gradient plasticity and a hydrogen- and fatigue-dependent cohesive zone model is presented and numerically implemented. T...
2204.07079v1
2022-07-12
Measurement of High Density Electrons Above a Helium Film on an Amorphous Metal Substrate
We have measured two-dimensional electron systems bound to a thin helium film supported by a metallic substrate. We report on our measurement of electron density obtained via a Kelvin probe technique. The underlying metallic substrate is an amorphous metallic alloy (TaWSi), which can support large uniform densities due...
2207.05864v1
2022-07-25
Experimental evaluation of a silicone oil as an oxidation inhibitor for magnesium alloy under contact sliding at elevated temperatures
This paper experimentally investigated the effects of silicone oil on the tribological behaviour of AZ31B/86CrMoV7 contact pair under a pin-on-disk configuration. A commercial silicone oil was used as an oxidation inhibiter for the AZ31B at elevated temperatures to 300 oC. The wear mechanism of the contact pair was exp...
2207.11908v1
2022-12-13
Machine learning superalloy microchemistry and creep strength from physical descriptors
We propose an element-agnostic set of descriptors to model superalloy properties with Gaussian process regression. Furthermore, we develop a correction method to deliver the best and most physical predictions for microchemistry in multi-phase alloys. The models' performance in predictions is confirmed for superalloy mi...
2212.06755v1
2023-03-09
Modeling metallic fatigue data using the Birnbaum--Saunders distribution
This work employs the Birnbaum--Saunders distribution to model the fatigue life of metallic materials under cyclic loading and compares it with the normal distribution. Fatigue-limit models are fitted to three datasets of unnotched specimens of 75S-T6 aluminum alloys and carbon laminate with different loading types. A ...
2303.05040v3
2023-03-10
Density of states for the Anderson model on nested fractals
We prove the existence and establish the Lifschitz singularity of the integrated density of states for certain random Hamiltonians $H^\omega=H_0+V^\omega$ on fractal spaces of infinite diameter. The kinetic term $H_0$ is given by $\phi(-\mathcal L),$ where $\mathcal L$ is the Laplacian on the fractal and $\phi$ is a co...
2303.05980v1
2023-05-31
Accelerating Optimal Elemental Configuration Search in Crystal using Ising Machine
This research demonstrates that Ising machines can effectively solve optimal elemental configuration searches in crystals, with Au-Cu alloys serving as an example. The energy function is derived using the cluster expansion method in the form of a QUBO function, enabling efficient problem-solving via Ising machines. We ...
2305.19625v1
2023-08-16
Solute Segregation in a Moving Grain Boundary: A Novel Phase-Field Approach
We present a novel phase-field approach for investigating solute segregation in a moving grain boundary. In our model, the correct choice of various parameters can control the solute-grain boundary interaction potential, resulting in various segregation profiles that agree with Cahn solute drag theory. Furthermore, we ...
2308.08262v1
2023-09-07
A Fully Coupled Multi-Physics Model to Simulate Phase Change Memory Operations in Ge-rich Ge$_2$Sb$_2$Te$_5$ Alloys
A self-consistent model for the simulation of Ge-rich Ge$_2$Sb$_2$Te$_5$ phase change memories is presented. Combining the multi-phase field model and a phase-aware electro-thermal solver, it reproduces the multi-physics behavior of the material. Simulations of memory operations are performed to demonstrate its ability...
2309.03768v1
2023-11-20
First principles residual resistivity using locally self-consistent multiple scattering method
The locally self-consistent multiple scattering (LSMS) method can perform efficient first-principles calculations of systems with large number of atoms. In this work, we combine the Kubo-Greenwood equation with LSMS, enabling us to calculate first-principles residual resistivity of large systems. This has been implemen...
2311.12134v1
2023-11-30
Electronic and spectral properties of Ge1-xSnx quantum dots: an atomistic study
In this paper, we study theoretically the electron and spectral properties of Ge1-xSnx systems, including alloys, cubic- and spherical quantum dots. The single-particle electron and hole states are calculated within the sp3d5s* tight-binding approach and used in further modeling of the optical properties. We systematic...
2311.18682v1
2024-01-11
Quantifying the contributions to diffusion in complex materials
Using machine learning with a variational formula for diffusivity, we recast diffusion as a sum of individual contributions to diffusion--called "kinosons"--and compute their statistical distribution to model a complex multicomponent alloy. Calculating kinosons is orders of magnitude more efficient than computing whole...
2401.06046v2
2024-01-30
A comprehensive diagram to grow InAlN alloys by plasma-assisted molecular beam epitaxy
Indium incorporation and surface morphology of InAlN layers grown on (0001)GaN by plasma-assisted molecular beam epitaxy were investigated as a function of the impinging In flux and the substrate temperature in the 450-610$^{\circ}$C range. In incorporation was found to decrease with substrate temperature due to therma...
2401.17340v1
2024-02-05
First principles evaluation of phase stability in the In-Sn binary system
The In-Sn binary alloy system exhibits several unusual features that challenge crystallographic and thermodynamic expectations. We combine first principles total energy calculation with simple thermodynamic modeling to address two key points. First, we evaluate energies along the Bain path to interpret the discontinuou...
2402.03506v1
2004-10-01
Mercury's Protoplanetary Mass
Major element fractionation among chondrites has been discussed for decades as ratios relative to Si or Mg. Recently, by expressing ratios relative to Fe, I discovered a new relationship admitting the possibility that ordinary chondrite meteorites are derived from two components, a relatively oxidized and undifferentia...
0410009v1
1996-10-22
Invertible and Non-invertible Alloy Ising Models
Physical properties of alloys are compared as computed from ``direct'' and ``inverse'' procedures. The direct procedure involves Monte Carlo simulations of a set of local density approximation (LDA)-derived pair and multibody interactions {\nu_f}, generating short-range order (SRO), ground states, order- disorder trans...
9610154v1
1997-12-30
Onset of magnetism in B2 transition metals aluminides
Ab initio calculation results for the electronic structure of disordered bcc Fe(x)Al(1-x) (0.4<x<0.75), Co(x)Al(1-x) and Ni(x)Al(1-x) (x=0.4; 0.5; 0.6) alloys near the 1:1 stoichiometry, as well as of the ordered B2 (FeAl, CoAl, NiAl) phases with point defects are presented. The calculations were performed using the co...
9712321v2
1998-01-19
Short range order in a steady state of irradiated Cu-Pd alloys: Comparison with fluctuations at thermal equilibrium
The equilibrium short-range order (SRO) in Cu-Pd alloys is studied theoretically. The evolution of the Fermi surface-related splitting of the (110) diffuse intensity peak with changing temperature is examined. The results are compared with experimental observations for electron-irradiated samples in a steady state, for...
9801184v1
1998-07-08
Local order and magnetic field effects on the electronic properties of disordered binary alloys in the Quantum Site Percolation limit
Electronic properties of disordered binary alloys are studied via the calculation of the average Density of States (DOS) in two and three dimensions. We propose a new approximate scheme that allows for the inclusion of local order effects in finite geometries and extrapolates the behavior of infinite systems following ...
9807125v1
1998-12-09
Ferromagnetism and the temperature-dependent electronic structure in thin Hubbard films
The magnetic behavior of thin ferromagnetic itinerant-electron films is investigated within the strongly correlated single-band Hubbard model. For its approximate solution we apply a generalization of the modified alloy analogy (MAA) to deal with the modifications due to the reduced translational symmetry. The theory i...
9812151v1
2000-02-10
Surface induced disorder in body-centered cubic alloys
We present Monte Carlo simulations of surface induced disordering in a model of a binary alloy on a bcc lattice which undergoes a first order bulk transition from the ordered DO3 phase to the disordered A2 phase. The data are analyzed in terms of an effective interface Hamiltonian for a system with several order parame...
0002161v1
2000-03-06
Non-Fermi Liquid Behavior in U and Ce Alloys: Criticality, Disorder, Dissipation, and Griffiths-McCoy singularities
In this paper we provide the theoretical basis for the problem of Griffiths-McCoy singularities close to the quantum critical point for magnetic ordering in U and Ce intermetallics. We show that the competition between Kondo effect and RKKY interaction can be expressed in Hamiltonian form and the dilution effect due to...
0003085v1
2000-04-19
Modified BCS mechanism of Cooper pair formation in narrow energy bands of special symmetry II. Matthias rule reconsidered
In part I of this paper a modified BCS mechanism of Cooper pair formation of electrons was proposed. This mechanism is connected with the existence of a narrow, roughly half-filled "superconducting energy band" of given symmetry. The special symmetry of the superconducting band was interpreted within a nonadiabatic ext...
0004324v1
2000-12-01
Hydrogen induced nonmonotonic relaxation in binary mixtures similar to Pd-Er alloys as a transition process in nonequilibrium heterogeneous systems with spinodal decomposition
We have proposed a qualitative model for the structure of binary systems similar to Pd-Er alloys, which explains their nonmonotonic relaxation after the hydrogen saturation. It is based on the assumption that such a solid solution involves two kind heterogeneities. The former are caused by spinodal decomposition of the...
0012012v1
2001-06-07
A Novel 2D Folding Technique for Enhancing Fermi Surface Signatures in the Momentum Density: Application to Compton Scattering Data from an Al-3at%Li Disordered Alloy
We present a novel technique for enhancing Fermi surface (FS) signatures in the 2D distribution obtained after the 3D momentum density in a crystal is projected along a specific direction in momentum space. These results are useful for investigating fermiology via high resolution Compton scattering and positron annihil...
0106139v1
2001-12-11
Eutectic colony formation: A phase field study
Eutectic two-phase cells, also known as eutectic colonies, are commonly observed during the solidification of ternary alloys when the composition is close to a binary eutectic valley. In analogy with the solidification cells formed in dilute binary alloys, colony formation is triggered by a morphological instability of...
0112194v1
2002-11-05
Effect of biaxial strain and composition on vacancy mediated diffusion in random binary alloys: A first principles study of the SiGe system
We present the results of a systematic study using the density functional theory (within the local density approximation) of the effects of biaxial strain and composition on the self-diffusion of Si and Ge in SiGe alloys diffusing by a vacancy mechanism. The biaxial strain dependence of the vacancy formation energy was...
0211072v1
2003-02-13
First-principles study of (BiScO3){1-x}-(PbTiO3){x} piezoelectric alloys
We report a first-principles study of a class of (BiScO3)_{1-x}-(PbTiO3)_x (BS-PT) alloys recently proposed by Eitel et al. as promising materials for piezoelectric actuator applications. We show that (i) BS-PT displays very large structural distortions and polarizations at the morphotropic phase boundary (MPB) (we obt...
0302277v2
2003-09-29
Simulation of Cu-Mg metallic glass: Thermodynamics and Structure
We have obtained effective medium theory (EMT) interatomic potential parameters suitable for studying Cu-Mg metallic glasses. We present thermodynamic and structural results from simulations of such glasses over a range of compositions. We have produced low-temperature configurations by cooling from the melt at as slow...
0309676v1
2004-02-04
Nucleation of Al3Zr and Al3Sc in aluminum alloys: from kinetic Monte Carlo simulations to classical theory
Zr and Sc precipitate in aluminum alloys to form the compounds Al3Zr and Al3Sc which for low supersaturations of the solid solution have the L12 structure. The aim of the present study is to model at an atomic scale this kinetics of precipitation and to build a mesoscopic model based on classical nucleation theory so a...
0402137v1
2004-02-23
A Biased Resistor Network Model for Electromigration Failure and Related Phenomena in Metallic Lines
Electromigration phenomena in metallic lines are studied by using a biased resistor network model. The void formation induced by the electron wind is simulated by a stochastic process of resistor breaking, while the growth of mechanical stress inside the line is described by an antagonist process of recovery of the bro...
0402557v2
2004-03-26
Exchange coupling and enhancement of Curie temperature of the intergranular amorphous region in nano-crystalline duplex-phase alloys system
We explored the magnetic behavior of a common two-phase nanomagnetic system by Monte Carlo computer simulation of a modified Heisenberg model on a 3D complex lattice with single- and cluster-spins. The effect of exchange coupling between two component magnetic phases was studied on the enhancement in Curie temperature ...
0403659v2
2004-04-20
Spin Susceptibility of Ga-Stabilized delta-Pu Probed by {69}^Ga NMR
Spin susceptibility of stabilized \delta phase in the Pu-Ga alloy is studied by measuring {69,71}^Ga NMR spectra and nuclear spin-lattice relaxation rate {69}T_{1}^{-1} in the temperature range 5 - 350 K. The shift ({69}^K) of the {69,71}^Ga NMR line and {69}^T_{1}^{-1} are controlled correspondingly by the static and ...
0404460v1
2004-04-27
Orbital and spin correlations in Ca$_{2-x}$Sr$_x$RuO$_4$: A mean field study
The alloy Ca$_{2-x}$Sr$_x$RuO$_4$ exhibits a complex phase diagram with peculiar magnetic metallic phases. In this paper some aspects of this alloy are discussed based on a mean field theory for an effective Kugel-Khomskii model of localized orbital and spin degrees of freedom. This model results from an orbital select...
0404661v1
2004-12-27
Vacancy-Mediated Disordering Process in Binary Alloys at Finite Temperatures: Monte Carlo Simulations
We have investigated the time evolution of the vacancy-mediated disordering process in binary alloys at finite temperatures. Qualitatively, we monitor the changes in the configurations by taking sequences of snapshots for various temperatures and comparing their morphologies. Quantitatively, we carry out Monte Carlo si...
0412699v1
2005-05-19
Competition between Superconductivity and Charge Density Wave Ordering in the Lu$_5$Ir$_4$(Si$_{1-x}$Ge$_x$)$_{10}$ Alloy System
We have performed bulk measurements such as dc magnetic susceptibility, electrical resistivity and heat capacity on the pseudo-ternary alloys Lu$_5$Ir$_4$(Si$_{1-x}$Ge$_x$)$_{10}$ to study the interplay and competition between superconductivity and the charge density wave (CDW) ordering transition. We track the evoluti...
0505463v1
2005-08-30
Susceptibility inhomogeneity and non-Fermi liquid behavior in UCu_{5-x}Pt_x
Transverse-field muSR shifts and relaxation rates have been measured in the non-Fermi liquid (NFL) alloy system UCu_{5-x}Pt_x, x = 1.0, 1.5, and 2.5. At low temperatures the fractional spread in Knight shifts delta K/K approx deltachi/chi is gtrsim 2 for x = 1, but is only half this value for x = 1.5 and 2.5. In a diso...
0508743v1
2005-09-14
Boron Spectral Density and Disorder Broadening in B-doped Diamond
Comparison of periodic B dopants with a random alloy of substitional boron in diamond is carried out using several supercells and the coherent potential approximation (CPA) for the random alloy case. The main peak in the B local density of states is shifted to lower binding energy compared to the corresponding C peak i...
0509359v2
2005-10-12
Electronic states and cyclotron resonance in p-type InMnAs and InMnAs/(Al,Ga)Sb at ultrahigh magnetic fields
We present a theoretical and experimental study on electronic and magneto-optical properties of p-type paramagnetic InMnAs dilute magnetic semiconductor alloys and ferromagnetic p-type InMnAs/(Al,Ga)Sb thin films in ultrahigh (> 100 T) external magnetic fields \textbf{B}. We use an 8 band Pidgeon-Brown model generalize...
0510323v1