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47
2013-07-29
Simple concentration-dependent pair interaction model for large-scale simulations of Fe-Cr alloys
This work is motivated by the need for large-scale simulations to extract physical information on the iron-chromium system that is a binary model alloy for ferritic steels used or proposed in many nuclear applications. From first-principles calculations and the experimental critical temperature we build a new energetic...
1307.7561v1
2013-07-31
Enhancement in the Figure of Merit of p-type BiSb alloys through multiple valence-band doping
N-type Bi100-xSbx alloys have the highest thermoelectric figure of merit (zT) of all materials below 200K; here we investigate how filling multiple valence band pockets at T and H-points of the Brillouin zone produces high zT in p-type Sn-doped material. This approach, theoretically predicted to potentially give zT>1 i...
1307.8224v2
2013-08-09
ZnO, ZnMnO and ZnCoO films grown by atomic layer deposition
Despite many efforts the origin of a ferromagnetic (FM) response in ZnMnO and ZnCoO is still not clear. Magnetic investigations of our samples, not discussed here, show that the room temperature FM response is observed only in alloys with a non-uniform Mn or Co distribution. Thus, the control of their distribution is c...
1308.2057v1
2013-08-20
A high-throughput ab initio review of platinum-group alloy systems
We report a comprehensive study of the binary systems of the platinum group metals with the transition metals, using high-throughput first-principles calculations. These computations predict stability of new compounds in 38 binary systems where no compounds have been reported in the literature experimentally, and a few...
1308.4357v4
2013-09-02
Recent progress in perpendicularly magnetized Mn-based binary alloy films
In this article, we review the recent progress in growth, structural characterization, magnetic properties and related spintronic devices of tetragonal MnxGa and MnxAl thin films with perpendicular magnetic anisotropy. In the first part of this review, we present a brief introduction to the demands for perpendicularly ...
1309.0298v2
2013-10-09
Nucleation of austenite in mechanically stabilized martensite by localized heating
The nucleation of bcc austenite in a single crystal of a mechanically stabilized 2H-martensite of Cu-Al-Ni shape-memory alloy is studied. The nucleation process is induced by localized heating and observed by optical microscopy. It is observed that nucleation occurs after a time delay and that the nucleation points are...
1310.2533v1
2013-10-16
Combined large spin-splitting and one dimensional confinement in surface alloys
We have found and characterized by angle-resolved photoelectron spectroscopy (ARPES) quasi-one dimensional spin-split states in chain-like surface alloys formed by large Z elements (Bi and Pb) at the Cu(110) surface. The ARPES results are supported by first-principles relativistic calculations, which also confirm the s...
1310.4277v1
2013-10-22
Effect of Epitaxial Strain on Phase Separation in Thin Films
We examine the role of an imposed epitaxial strain e in enhancing or depressing the spinodal instability of an alloy thin film. Since the alloy film starts with an imposed strain, phase separation offers a mechanism to relieve it, but only when the film is elastically inhomogeneous. With composition-dependence of elast...
1310.5899v1
2013-10-31
Single crystal growth and characterization of the large-unit-cell compound Cu13Ba
Single crystals of Cu$_{13}$Ba were successfully grown out of Ba-Cu self flux. Temperature dependent magnetization, $M(T)$, electrical resistivity, $\rho(T)$, and specific heat, $C_p(T)$, data are reported. Isothermal magnetization measurements, $M(H)$, show clear de Haas-van Alphen oscillations at $T$ = 2 K for applie...
1311.0027v1
2013-11-05
Mixed valency and site-preference chemistry for Cerium and its compounds: A predictive DFT study
Cerium and its technologically relevant compounds are examples of anomalous mixed valency, originating from two competing oxidation states -- itinerant Ce$^{3+}$ and localized Ce$^{4+}$. Under applied stress, anomalous transitions are observed but not well understood. Here we treat mixed valency as an "alloy" involving...
1311.0962v1
2013-11-05
Fermi surface and electron dispersions of PbTe doped with resonant Tl impurity from KKR-CPA calculations
We present results of detailed study on the electron dispersions and Fermi surface of lead telluride doped with $2\%$ of thallium, which is resonant impurity in PbTe. Using the KKR--CPA method, Bloch spectral functions (BSFs), which replace the dispersion relations in alloys, are calculated, and BSFs intensity maps ove...
1311.1014v1
2013-11-05
Diffusion behavior in diluted ($Fe,Cr$) alloys: An environment for H diffusion in ferritic steels
Impurity diffusion coefficients are entirely obtained from a low cost classical molecular statics technique (CMST). In particular, we show how the CMST is appropriate in order to describe the impurity diffusion behavior mediated by a vacancy mechanism. In the context of the five-frequency model, CMST allows to calculat...
1311.1177v1
2013-11-12
Undercooling growth and magnetic characterization of ferromagnetic shape memory alloy Ni2FeGa single crystals
Ni2FeGa single crystals have been grown in undercooling conditions provided by a glass-purification method. It has been found that trace amounts of gamma phase embededin the single crystalline matrix preferentially orients in the <100> orientation along the growth direction. This gamma phase generates directional resid...
1311.2729v1
2013-11-20
Supplemental Material to "A first-principles linear response description of the spin Nernst effect"
A first-principles description of the spin Nernst effect, denoting the occurrence of a transverse spin current due to a temperature gradient, is presented. The approach, based on an extension to the Kubo-Streda equation for spin transport, supplies in particular the formal basis for investigations of diluted as well as...
1311.5047v1
2013-12-27
A second binding model to study diffusion of $Cr$ diluted in BCC $Fe$
A classical molecular static technique (CMST) and DFT calculations using SIESTA, are employed here to characterize the self diffusion and the tracer solute diffusion in the bulk of BCC diluted $FeCr$ alloy driven by both vacancy and interstitial migration. For the first time in the literature, a six-frequency model (de...
1312.7290v1
2014-01-09
From local moment to mixed-valence regime in Ce(1-x)Yb(x)CoIn5 alloys
We investigated the onset of the many-body coherence in the f-orbital single crystalline alloys Ce(1-x)Yb(x)CoIn5 through thermodynamic and magneto-transport measurements. Our study shows the evolution of the many-body electronic state as the Kondo lattice of Ce moments is transformed into an array of Ce impurities. Sp...
1401.1881v2
2014-02-03
Atomistic tight-binding study of electronic structure and interband optical transitions in GaBi$_{x}$As$_{1-x}$/GaAs quantum wells
Large-supercell tight-binding calculations are presented for GaBi$_{x}$As$_{1-x}$/GaAs single quantum wells (QWs) with Bi fractions $x$ of 3.125% and 12.5%. Our results highlight significant distortion of the valence band states due to the alloy disorder. A large full-width-half-maximum (FWHM) is estimated in the groun...
1402.0310v1
2014-02-12
Refinement of Nb3Sn grain size by the generation of ZrO2 precipitates in Nb3Sn wires
In this letter we demonstrate that if oxygen can be properly supplied to (Nb-Zr)-Sn wires, ZrO2 precipitates will form during the heat treatment, refining the Nb3Sn grain size markedly. Here, a Nb3Sn subelement was fabricated in which Nb-1Zr alloy was used, and oxygen was supplied via SnO2 powder. The results showed th...
1402.3001v2
2014-03-21
Three Dimensional Non-Isothermal Ginzburg-Landau Phase-Field Model for Shape Memory Alloys
In this paper, a macroscopic three dimensional non-isothermal model is proposed to describe hysteresis phenomena and phase transformations in shape memory alloys (SMAs). The model is of phase-field type and is based on the Ginzburg-Landau theory. The hysteresis and phase transformations are governed by the kinetic phas...
1403.5340v1
2014-03-22
3D Coupled Thermo-Mechanical Phase-Field Modeling of Shape Memory Alloy Dynamics via Isogeometric Analysis
The paper focuses on numerical simulation of the phase-field (PF) equations for modeling martensitic transformations in shape memory alloys (SMAs), their complex microstructures and thermo-mechanical behavior. The PF model is based on the Landau-Ginzburg potential for the 3D cubic-to-tetragonal phase transformations in...
1403.5612v1
2014-03-24
Temperature Induced Cubic-to-Tetragonal Transformations in Shape Memory Alloys Using a Phase-Field Model
Shape memory alloys (SMAs) exhibit hysteresis behaviors upon stress and temperature induced loadings. In this contribution, we focus on numerical simulations of microstructure evolution of cubic-to-tetragonal martensitic phase transformations in SMAs in 3D settings under the dynamic loading conditions. A phase-field (P...
1403.5966v1
2014-03-24
Shape Memory Alloy Nanostructures With Coupled Dynamic Thermo-Mechanical Effects
Employing the Ginzburg-Landau phase-field theory, a new coupled dynamic thermo-mechanical 3D model has been proposed for modeling the cubic-to-tetragonal martensitic transformations in shape memory alloy (SMA) nanostructures. The stress-induced phase transformations and thermo-mechanical behavior of nanostructured SMAs...
1403.6133v2
2014-03-25
Fermi surfaces and Phase Stability of Ba(Fe$_{1-x}$M$_x$)$_2$As$_2$ (M=Co, Ni, Cu, Zn)
BaFe$_2$As$_2$ with transition-metal doping exhibits a variety of rich phenomenon from coupling of structure, magnetism, and superconductivity. Using density functional theory, we systematically compare the Fermi surfaces (FS), formation energies ($\Delta E_f$), and density of states (DOS) of electron-doped Ba(Fe$_{1-x...
1403.6500v2
2014-04-05
Gilbert damping in noncollinear ferromagnets
The precession and damping of a collinear magnetization displaced from its equilibrium are described by the Landau-Lifshitz-Gilbert equation. For a noncollinear magnetization, it is not known how the damping should be described. We use first-principles scattering theory to investigate the damping in one-dimensional tra...
1404.1488v2
2014-04-28
Electronic structure and magnetic properties of L1_0 binary alloys
We present a systematic study of the magnetic properties of L1$_0$ binary alloys FeNi, CoNi, MnAl and MnGa via two different density functional theory approaches. Our calculations show large magnetocrystalline anisotropies in the order $1~\text{MJ/m}^3$ or higher for CoNi, MnAl and MnGa while FeNi shows a somewhat lowe...
1404.7097v2
2014-04-30
Importance of frequency-dependent grain boundary scattering in nanocrystalline silicon and silicon-germanium thermoelectrics
Nanocrystalline silicon and silicon-germanium alloys are promising thermoelectric materials that have achieved substantially improved figure of merits compared to their bulk counterparts. This enhancement is typically attributed to a reduction in lattice thermal conductivity by phonon scattering at grain boundaries. Ho...
1404.7847v1
2014-02-25
Liquid Phase 3D Printing for Quickly Manufacturing Metal Objects with Low Melting Point Alloy Ink
Conventional 3D printings are generally time-consuming and printable metal inks are rather limited. From an alternative way, we proposed a liquid phase 3D printing for quickly making metal objects. Through introducing metal alloys whose melting point is slightly above room temperature as printing inks, several represen...
1405.0199v1
2014-05-06
In my Wish List, an Automated Tool for Fail-Secure Design Analysis: an Alloy-Based Feasibility Draft
A system is said to be fail-secure, sometimes confused with fail-safe, if it maintains its security requirements even in the event of some faults. Fail-secure analyses are required by some validation schemes, such as some Common Criteria or NATO certifications. However, it is an aspect of security which as been overloo...
1405.1115v1
2014-07-01
Anomalous ideal tensile strength of ferromagnetic Fe and Fe-rich alloys
Within the same failure mode, iron has the lowest ideal tensile strength among the transition metals crystallizing in the body-centered cubic structure. Here, we demonstrate that this anomalously low strength of Fe originates partly from magnetism and is reflected in unexpected alloying effects in dilute Fe(\emph{M}) (...
1407.0289v1
2014-07-22
Emergence of localized plasticity and failure through shear banding during microcompression of a nanocrystalline alloy
Microcompression testing is used to probe the uniaxial stress-strain response of a nanocrystalline alloy, with an emphasis on exploring how grain size and grain boundary relaxation state impact the complete flow curve and failure behavior. The yield strength, strain hardening, strain-to-failure, and failure mode of nan...
1407.5925v1
2014-07-22
Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling
Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in a W-1%Re alloy after implantation with 3110 appm of helium. A fraction of a percent observed lattice expansion gives rise to an order of magnitude larger reduction in the surface acoustic wav...
1407.6051v1
2014-08-06
Synthesis, single crystal growth and properties of $Sr_5Pb_3ZnO_{12}$
The novel $Sr_5Pb_3ZnO_{12}$ oxide was synthesized by the solid-state reaction method. The crystal structure was studied by means of the powder x-ray diffraction Rietveld method and was found to be similar to 3 other previously known $Sr_5Pb_3MO_{12}$ compounds (M = Co, Ni, Cu). Crystals of several hundred microns in s...
1408.1241v1
2014-08-28
Special quasirandom structure in heterovalent ionic systems
The use of a special quasirandom structure (SQS) is a rational and efficient way to approximate random alloys. A wide variety of physical properties of metallic and semiconductor random alloys have been successfully estimated by a combination of an SQS and density functional theory (DFT) calculation. Here, we investiga...
1408.6875v1
2014-09-12
Effect of quenching medium on short-range order in Fe-rich Fe-Cr alloys
Effect of a quenching medium (water, liquid nitrogen and block of brass) on a short-range ordering in Fe(100-x)Cr(x) (x less than 19) alloys was studied with the Moessbauer spectroscopy. The distribution of Cr atoms was expressed in terms of the Cowley-Warren short-range order (SRO) parameters: alpha1 for the first nei...
1409.3684v1
2014-09-17
Incommensurate modulations in stoichiometric Ni2MnGa ferromagnetic shape memory alloy: An overview
This article presents a brief overview of our recent work on the nature of long period modulation in the premartensite and martensite phases of Ni2MnGa ferromagnetic shape memory alloy using high resolution synchrotron x-ray powder diffraction patterns. The commensurate structure model using the Pnnm space group is una...
1409.4902v1
2014-09-24
Temperature dependence of irradiation hardening due to dislocation loops and precipitates in RPV steels and model alloys
A relative contribution to irradiation hardening caused by dislocation loops and solute-rich precipitates is established for RPV steels of WWER-440 and WWER-1000 reactors, based on TEM measurements and mechanical testing at reactor operating temperature of 563 K. The pinning strength factors evaluated for loops and pre...
1409.6807v1
2014-10-07
First-principles study of the lattice instabilities in Mn$_{2}$Ni{\it X} ({\it X}= Al, Ga, In, Sn) magnetic shape memory alloys
Using first-principles based Density Functional Theory (DFT), we have investigated the structural instabilities in the austenite phases of Mn$_{2}$Ni{\it X} ({\it X}= Al, Ga, In, Sn) magnetic shape memory alloys (MSMA). A complete softening is observed in the acoustic TA$_{2}$ branches for all the materials along [$\xi...
1410.1688v1
2014-11-28
Analysis of the spin Hall effect in CuIr alloys: Combined approach of density functional theory and Hartree-Fock approximation
We analyze the spin Hall effect in CuIr alloys in theory by the combined approach of the density functional theory (DFT) and Hartree-Fock (HF) approximation. The SHA is obtained to be negative without the local correlation effects. After including the local correlation effects of the 5d orbitals of Ir impurities, the S...
1411.7733v1
2014-12-01
All-optical magnetization switching in ferrimagnetic alloys: deterministic vs thermally activated dynamics
Using photo-emission electron microscopy with X-ray magnetic circular dichroism as a contrast mechanism, new insights into the all-optical magnetization switching (AOS) phenomenon in GdFe based rare-earth transition metal ferrimagnetic alloys are provided. From a sequence of static images taken after single linearly po...
1412.0396v1
2015-01-07
Effects of pressure on the magnetostructural and magnetocaloric properties of isostructurally alloyed (MnNiSi)1-x(FeCoGe)x
The isostructural alloying of two compounds with extremely different magnetic and thermo-structural properties has resulted in a new system, (MnNiSi)1-x(FeCoGe)x, that exhibits extraordinary magnetocaloric properties with an acute sensitivity to applied hydrostatic pressure (P). Application of hydrostatic pressure shif...
1501.01659v1
2015-01-12
Ab initio construction of magnetic phase diagrams in alloys: The case of Fe$_{1-x}$Mn$_x$Pt
A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account f...
1501.02794v2
2015-01-14
Origin of the spin reorientation transitions in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys
Low-temperature measurements of the magnetocrystalline anisotropy energy $K$ in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are reported, and the origin of this anisotropy is elucidated using a first-principles electronic structure analysis. The calculated concentration dependence $K(x)$ with a maximum near $x=0.3$ and a minimu...
1501.03483v2
2015-01-22
Dynamical properties of ordered Fe-Pt alloys
The structure, magnetic properties, and lattice dynamics of ordered Fe-Pt alloys with three stoichiometric compositions, Fe$_3$Pt, FePt and FePt$_3$, have been investigated using the density functional theory. Additionally, the existing experimental data have been complemented by new measurements of the Fe projected ph...
1501.05550v1
2015-02-04
Is inner core seismic anisotropy a marker of plastic flow of cubic iron?
This paper investigates whether observations of seismic anisotropy are compatible with a cubic structure of the inner core Fe alloy. We assume that anisotropy is the result of plastic deformation within a large scale flow induced by preferred growth at the inner core equator. Based on elastic moduli from the literature...
1502.01270v1
2015-02-17
Strain intermittency in shape-memory alloys
We study experimentally the intermittent progress of the mechanically induced martensitic transformation in a Cu-Al-Be single crystal through a full-field measurement technique: the grid method. We utilize an in- house, specially designed gravity-based device, wherein a system controlled by water pumps applies a perfec...
1502.06567v3
2015-02-23
Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains
We report here an atomistic study of the mechanical deformation of AuxCu(1-x) atomic-size wires (NWs) by means of high resolution transmission electron microscopy (HRTEM) experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. Th...
1502.06647v1
2015-02-25
Atomistic simulations of the structures of Pd-Pt bimetallic nanoparticles and nanowires
Bimetallic nanoalloys such as nanoparticles and nanowires are attracting significant attention due to their vast potential applications such as in catalysis and nanoelectronics. Notably, Pd-Pt nanoparticles/nanowires are being widely recognized as catalysts and hydrogen sensors. Compared to unary systems, alloys presen...
1502.07372v1
2015-03-10
Synthesis of large single-crystal hexagonal boron nitride grains on Cu-Ni alloy
Hexagonal boron nitride (h-BN) has attracted significant attention due to its superior properties as well as its potential as an ideal dielectric layer for graphene-based devices. The h-BN films obtained via chemical vapor deposition in earlier reports are always polycrystalline with small grains due to high nucleation...
1503.02804v1
2015-03-12
Characterizing the greater-than-bulk melting behaviour of Ga-Al nanoalloys
Phase diagrams are the most reliable way of predicting phase changes in a system. In this work, we create the phase diagram of the Ga(20-x)Al(x)+ bimetallic cluster system, for which the monometallic clusters display greater-than- bulk melting behaviour. Employing first-principles Born-Oppenheimer molecular dynamics in...
1503.03629v2
2015-03-24
On the magnetism of sigma-Fe54Cr46 alloy: AC and DC susceptibility studies
Sigma-phase intermetallic compound of Fe54Cr46 was investigated using DC and AC magnetic susceptibility techniques. A clear-cut evidence was found that the sample orders magnetically at Tc=23.5 K and its ground magnetic state is constituted by a spin glass. The temperature at which the zero-field cooled magnetization h...
1503.06991v1
2015-03-30
Shear melting and high temperature embrittlement: theory and application to machining titanium
We describe a dynamical phase transition occurring within a shear band at high temperature and under extremely high shear rates. With increasing temperature, dislocation deformation and grain boundary sliding is supplanted by amorphization in a highly localized nanoscale band, which allows massive strain and fracture. ...
1503.08662v1
2015-04-05
Artificial fireball generation via an erosive discharge with tin alloy electrodes
We propose a method for generation of long-living autonomous fireball-like objects via a pulse erosive discharge between tin alloy electrodes. The objects are similar to the natural ball lightning in some properties, in particular, they have high energy density and are capable to burn through thin metal foils. The dyna...
1504.01120v1
2015-04-11
Injectable Spontaneous Generation of Tremendous Self-Fueled Liquid Metal Droplet Motors in a Moment
Micro motors that could run in liquid environment is very important for a variety of practices such as serving as pipeline robot, soft machine, drug delivery, or microfluidics system etc. However, fabrication of such tiny motors is generally rather time and cost consumptive and has been a tough issue due to involve too...
1504.02851v1
2015-04-11
Magnetic response of a disordered binary ferromagnetic alloy to an oscillating magnetic field
By means of Monte Carlo simulation with local spin update Metropolis algorithm, we have elucidated non-equilibrium phase transition properties and stationary-state treatment of a disordered binary ferromagnetic alloy of the type $A_{p}B_{1-p}$ on a square lattice. After a detailed analysis, we have found that the syste...
1504.02874v1
2015-04-14
Thermal boundary resistance at Si/Ge interfaces determined by approach-to-equilibrium molecular dynamics simulations
The thermal boundary resistance of Si/Ge interfaces as been determined using approach-to-equilibrium molecular dynamics simulations. Assuming a reciprocal linear dependence of the thermal boundary resistance, a length-independent bulk thermal boundary resistance could be extracted from the calculation resulting in a va...
1504.03613v1
2015-04-22
Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations
The structures and magnetic properties of the Co-Zr-B alloys near the Co5Zr composition were studied using adaptive genetic algorithm and first-principles calculations to guide further experimental effort on optimizing their magnetic performances. Through extensive structural searches, we constructed the contour maps o...
1504.05829v1
2015-04-27
Electronic stress tensor analysis of molecules in gas phase of CVD process for GeSbTe alloy
We analyze the electronic structure of molecules which may exist in gas phase of chemical vapor deposition process for GeSbTe alloy using the electronic stress tensor, with special focus on the chemical bonds between Ge, Sb and Te atoms. We find that, from the viewpoint of the electronic stress tensor, they have interm...
1504.06910v1
2015-05-06
Magnetoresistance control in granular Zn/1-x-y/Cd/x/Mn/y/GeAs/2/ nanocomposite ferromagnetic semiconductors
We present studies of structural, magnetic and electrical properties of Zn/1-x-y/Cd/x/Mn/y/GeAs/2/ nanocomposite ferromagnetic semiconductor samples with changeable chemical composition. The presence of MnAs clusters induces in the studied alloy room temperature ferromagnetism with the Curie temperature, TC, around 305...
1505.01357v1
2015-06-08
Influence of mass contrast in alloy phonon scattering
We have investigated the effect of mass contrast on alloy phonon scattering in mass-substituted Lennard-Jones crystals. By calculating the mass-difference phonon scattering rate using a modal analysis method based on molecular dynamics, we have identified the applicability and limits of the widely-used mass-difference ...
1506.02365v1
2015-06-12
Determination of the vibrational contribution to the entropy change at the martensitic transformation in Ni-Mn-Sn metamagnetic shape memory alloys: A combined approach of time-of-flight neutron spectroscopy and ab-initio calculations
The different contributions to the entropy change linked to the austenite-martensitic transition in a Ni-Mn-Sn metamagnetic shape memory alloy have been determined by combining different experimental techniques. The vibrational contribution has been inferred from the vibrational density of states of both the martensiti...
1506.04100v2
2015-06-18
Temperature dependent determination of electron heat capacity and electron-phonon factor for Fe$_{0.72}$Cr$_{0.18}$Ni$_{0.1}$
A theoretical approach using ab initio calculations has been applied to study the interaction of an ultra-short laser pulse with the metal alloy Fe$_{0.72}$Cr$_{0.18}$Ni$_{0.1}$ (AISI 304). The electronic structure is simulated by taking into account the chemical and magnetic disorder of the alloy by the coherent poten...
1506.05760v1
2015-06-24
Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor
Recently, focused electron beam induced deposition has been employed to prepare functional magnetic nanostructures with potential in nanomagnetic logic and sensing applications by using homonuclear precursor gases like Fe(CO)5 or Co2(CO)8. Here we show that an extension towards the fabrication of bi-metallic compounds ...
1506.07311v1
2015-06-29
The band-gap of Tl-doped gallium nitride alloys
Structural and electronic properties of hypothetical zinc blende Tl(x)Ga(1-x)N alloys have been investigated from first principles. The structural relaxation, preformed within the LDA approach, leads to a linear dependence of the lattice parameter a on the Tl content x. In turn, band structures obtained by MBJLDA calcu...
1506.08577v1
2015-07-10
High-temperature stability and grain boundary complexion formation in a nanocrystalline Cu-Zr alloy
Nanocrystalline Cu-3 at.% Zr powders with ~20 nm average grain size were created with mechanical alloying and their thermal stability was studied from 550-950 {\deg}C. Annealing drove Zr segregation to the grain boundaries, which led to the formation of amorphous intergranular complexions at higher temperatures. Grain ...
1507.02944v2
2015-07-12
Non-equilibrium behavior of the magnetization in the helimagnetic phases of the rare earth alloys R_{1-x}Y_{x} (R = Gd, Tb, Dy)
We have performed DC and AC magnetization measurements for the rare-earth magnetic alloy systems Gd_{0.62}Y_{0.38}, Tb_{0.86}Y_{0.14}, and Dy_{0.97}Y_{0.03}. These materials commonly exhibit a proper helical magnetic structure, and ferromagnetic structure at lower temperatures.In all of these materials, a difference be...
1507.03202v3
2015-07-16
Emerging frustration effects in ferromagnetic Ce_2[Pd_{1-x}Ag_x]_2In alloys
Magnetic and thermal properties of Ferromagnetic (FM) Ce_{2.15}(Pd_{1-x}Ag_x)_{1.95}In_{0.9} alloys were studied in order to determine the Quantum Critical Point (QCP) at T_C => 0. The increase of band electrons produced by Pd/Ag substitution depresses T_C(x) from 4.1K down to T_C(x=0.5)=1.1K, with a QCP extrapolated t...
1507.04689v1
2015-07-21
Unprecedentedly Wide Curie-Temperature Windows as Phase-Transition Design Platform for Tunable Magneto-Multifunctional Materials
A series of unprecedentedly wide Curie-temperature windows (CTWs) between 40 and 450 K are realized by employing the isostructural alloying principle for the strongly coupled magnetostructural phase transitions in a single host system. The CTWs provide a design platform for magneto-multifunctional multiferroic alloys t...
1507.05905v1
2015-07-23
Electronic, magnetic and transport properties of Fe intercalated 2H-TaS$_2$ studied by means of the KKR-CPA method
The electronic, magnetic and transport properties of Fe intercalated 2H-TaS$_2$ have been investigated by means of the Korringa-Kohn-Rostoker (KKR) method. The non-stoichiometry and disorder in the system has been accounted for using the Coherent Potential Approximation (CPA) alloy theory. A pronounced influence of dis...
1507.06544v1
2015-07-24
Analysis and modelling of a rotary forming process for cast aluminum alloy A356
Spinning of a common aluminum automotive casting alloy A356 (Al-7Si-0.3 Mg) at elevated temperatures has been investigated experimentally with a novel industrial-scale apparatus. This has permitted the implementation of a fully coupled thermomechanical finite element model aimed at quantifying the processing history (s...
1507.06938v1
2015-08-03
Spin orbit coupling controlled spin pumping effect
Effective spin mixing conductance (ESMC) across the nonmagnetic metal (NM)/ferromagnet interface, spin Hall conductivity (SHC) and spin diffusion length (SDL) in the NM layer govern the functionality and performance of pure spin current devices with spin pumping technique. We show that all three parameters can be tuned...
1508.00352v3
2015-07-31
Elastic Properties of FeC and FeN Martensites
Single crystal elastic constants of bcc iron and bct FeC and FeN alloys, martensites, have been evaluated by ab initio calculations based on the density functional theory. The energy of a strained crystal has been computed using the supercell method at several values of the strain intensity, and the stiffness coefficie...
1508.00521v1
2015-08-05
Origin of giant magnetoresistance across the martensitic transformation for Ni44Cu2Mn43In11 alloy: Formation of phase fraction
We have studied the phase volume fraction related magnetoresistance (MR) across the first order martensite transformation (MT) of Ni44Cu2Mn43In11 alloy. Within the metastability of MT, an isothermal application of magnetic field converts the martensite into austenite. The field induced austenite phase fraction (fIA) at...
1508.01085v1
2015-08-11
Testing Predictions from Density Functional Theory at Finite Temperatures: $β_2$-Like Ground States in Co-Pt
We perform a critical assessment of the accuracy of DFT-based methods in predicting stable phases within the Co-Pt binary alloy. Statistical mechanical analysis applied to zero kelvin DFT predictions yields finite-temperature results that can be directly compared with experimental measurements. The predicted temperatur...
1508.02737v1
2015-08-17
The effect of hydrostatic pressure and uniaxial strain on the electronic structure of Pb$_{\text{1-x}}$Sn$_{\text{x}}$Te
The electronic structure of Pb$_{1-x}$Sn$_{x}$Te is studied by using the relativistic Korringa-Kohn-Rostoker Green function method in the framework of density functional theory. For all concentrations $x$, Pb$_{1-x}$Sn$_{x}$Te is a direct semiconductor with a narrow band gap. In contrast to pure lead telluride, tin tel...
1508.04113v1
2015-09-28
Femtosecond structural transformation of phase-change materials far from equilibrium monitored by coherent phonons
Multi-component chalcogenides, such as quasi-binary GeTe-Sb$_{2}$Te$_{3}$ alloys, are widely used in optical data storage media in the form of rewritable optical discs. Ge$_{2}$Sb$_{2}$Te$_{5}$ (GST) in particular has proven to be one of the best-performing materials, whose reliability allows more than 10$^{6}$ write-e...
1509.08187v1
2015-09-29
Laser-induced reversion of $δ^{'}$ precipitates in an Al-Li alloy: Study on temperature rise in pulsed laser atom probe
The influence of tuning the laser energy during the analyses on the resulting microstructure in a specimen utilizing an ultra-fast laser assisted atom probe was demonstrated by a case study of a binary Al-Li alloy. The decomposition parameters, such as the size, number density, volume fraction and composition of $\delt...
1509.08785v1
2015-10-01
Co-sputtered MoRe thin films for carbon nanotube growth-compatible superconducting coplanar resonators
Molybdenum rhenium alloy thin films can exhibit superconductivity up to critical temperatures of $T_c=15\mathrm{K}$. At the same time, the films are highly stable in the high-temperature methane / hydrogen atmosphere typically required to grow single wall carbon nanotubes. We characterize molybdenum rhenium alloy films...
1510.00278v1
2015-10-10
Atom probe microscopy investigation of Mg site occupancy within δ precipitates in an Al Mg Li alloy
The composition and site occupancy of Mg within ordered {\delta} precipitates in a model Al Mg Li alloy have been characterized by atom probe microscopy and first-principles simulations. The concentration in the precipitates is found to be almost the same as that of the matrix, however, we show evidence that Mg partiti...
1510.02910v1
2015-10-10
Microstructural evolution during ageing of Al-Cu-Li-x alloys
In this study atom probe tomography was used to investigate the microstructure of AA2198 (Al-1.35Cu-3.55Li-0.29Mg-0.08Ag) over a range of ageing conditions to examine the evolution of phases in the alloy, in particular aiming to reveal the nucleation mechanism of the strengthening T1 phase, which has been under debate ...
1510.02917v1
2015-10-27
Unraveling the "Green Gap" problem: The role of random alloy fluctuations in InGaN/GaN light emitting diodes
White light emitting diodes based on III-nitride InGaN/GaN quantum wells currently offer the highest overall efficiency for solid state lighting applications. Although current phosphor-converted white LEDs have high electricity-to-light conversion efficiencies, it has been recently pointed out that the full potential o...
1510.07831v1
2015-11-04
Band engineering of ternary metal nitride system Ti1-x ZrxN for plasmonic applications
Chemical composition is the primary factor that determines the electronic band structure and thus also influences the optical properties of plasmonic ceramics including nitrides and oxides. In this work, the optical and plasmonic properties of TiN, ZrN and their hypothetical intermediate alloys Ti1-xZrxN (x= 0, 0.25, 0...
1511.01179v3
2015-11-17
Microstructure, mechanical properties and corrosion of friction stir welded 6061 Aluminum Alloy
The microstructure, mechanical properties, and corrosion behavior of friction stir welded (FSW) AA6061 aluminum alloys were investigated. Dynamic recrystallized structures were observed and grain sizes of nugget zone (NZ), thermomechanically-affected zone (TMAZ), heat-affected zone (HAZ), and base material (BM) were di...
1511.05507v1
2015-11-27
Magnetic properties of Fe$_{1-x}$Ni$_x$ alloy from CPA+DMFT perspectives
We use a combination of the coherent potential approximation and dynamical mean field theory to study magnetic properties of the Fe$_{1-x}$Ni$_x$ alloy from a first principles. Calculated uniform magnetic susceptibilities have a Curie-Weiss-like behavior and extracted effective temperatures are in agreement with the ex...
1511.08625v2
2015-11-27
Stacking fault energy of face-centered cubic metals: thermodynamic and ab initio approaches
The formation energy of the interface between face-centered cubic (fcc) and hexagonal close packed (hcp) structures is a key parameter in determining the stacking fault energy (SFE) of fcc metals and alloys using thermodynamic calculations. Often the contribution of the planar fault energy to the SFE has the same order...
1511.08634v1
2015-12-08
Estimating the compressibility of osmium from recent measurements of Ir-Os alloys under high pressure
Several fcc- and hcp-structured Ir-Os alloys have been recently studied up to 30 GPa at room temperature by means of synchrotron-based X-ray powder diffraction in diamond anvil cells. Using their bulk moduli -which increase with increasing osmium content showing a deviation from linearity- and after employing a thermod...
1512.02417v1
2015-12-15
Bismuth-content dependent of the polarized Raman spectra of the InPBi alloys
We have systematically investigated the optical properties of the InP1-xBix ternary alloys with 0<x<2.46%, using high resolution polarized Raman scattering measurement. Both InP-like and InBi-like optical vibration modes (LO) were identified in all the samples, suggesting most of the Bi-atoms are incorporated into the ...
1512.04634v1
2015-12-30
Multiple first order transitions and associated room temperature magneto-functionality in Ni2.048Mn1.312In0.64
Present work reports on the observation of multiple magnetic transitions in a Ni-excess ferromagnetic shape memory alloy with nominal composition Ni$_{2.048}$Mn$_{1.312}$In$_{0.64}$. The magnetization data reveal two distinct thermal hystereses associated with two different phase transitions at different temperature re...
1512.08909v1
2015-12-07
Bulk moduli of PbS$_{x}$Se$_{1-x}$, PbS$_{x}$Te$_{1-x}$ and PbSe$_{x}$Te$_{1-x}$ from a thermodynamical model compared to generalized gradient approximation approach
Very recently, first-principle technique of full-potential linearized augmented plane-wave method, by using for exchange-correlation potential the generalized gradient approximation (GGA), was employed for the study of the lead chalcogenide semiconductors' alloys PbS$_{x}$Se$_{1-x}$, PbS$_{x}$Te$_{1-x}$ and PbSe$_{x}$T...
1512.09373v1
2016-01-10
Hydrogen Isotope Trapping in Al-Cu Binary Alloys
The trapping mechanisms for hydrogen isotopes in Al-X Cu (0.0 at.% < X < 3.5 at.%) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addit...
1601.02279v1
2016-01-14
NH3 adsorption on PtM (Fe, Co, Ni) surfaces: cooperating effects of charge transfer, magnetic ordering and lattice strain
Adsorption of a molecule or group with an atom which is less electronegative than oxygen (O) and directly interacting with the surface is very relevant to development of PtM (M=3d-transition metal) catalysts with high activity. Here, we present theoretical analysis of the adsorption of NH3 molecule (N being less electr...
1601.03490v1
2016-01-14
Effect of co-existing crystal structures on magnetic properties of Ni_2Mn_(1+x)Sn_(1-x) magnetic shape memory alloy
The temperature dependent crystal structure analysis in martensitic phase of Ni_2Mn_(1+x)Sn_(1-x) (x = 0.40 and 0.44) magnetic shape memory alloy is performed using X-ray diffraction. The martensitic phase consists of 4-Layered and 14-Layered orthorhombic structure. The phase fraction of 4-layered and 14-layered orthor...
1601.03554v5
2016-01-29
Stability of the $ω$ structure of transition elements
Properties of the $\omega$ structure are investigated for 27 transition elements from the viewpoints of thermodynamical and mechanical stability based on first-principles calculations. The thermodynamical stability of the $\omega$ structure is compared with those for the body-centered cubic (BCC), face-centered cubic (...
1601.07980v1
2016-02-04
High-Throughput ab-initio Dilute Solute Diffusion Database
We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for...
1602.01725v1
2016-02-17
Growth in multi-component alloys: Theoretical and numerical determination of phase concentrations
Understanding the role of solute diffusivities in equilibrium tie-line selection during growth of a second phase in ternary and higher multicomponent two phase alloys is an important problem due to the strong dependence of mechanical properties on compositions. In this paper, we derive analytical expressions for predic...
1602.05341v2
2016-02-24
Lattice Boltzmann simulations of 3D crystal growth: Numerical schemes for a phase-field model with anti-trapping current
A lattice-Boltzmann (LB) scheme, based on the Bhatnagar-Gross-Krook (BGK) collision rules is developed for a phase-field model of alloy solidification in order to simulate the growth of dendrites. The solidification of a binary alloy is considered, taking into account diffusive transport of heat and solute, as well as ...
1602.07483v1
2016-02-24
Local motifs in GeS$_2$-Ga$_2$S$_3$ glasses
The structure of (GeS$_2$)$_{0.75}$(Ga$_2$S$_3$)$_{0.25}$ and (GeS$_2$)$_{0.83}$(Ga$_2$S$_3$)$_{0.17}$ glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC...
1602.07606v2
2016-06-16
Potential improvement for elastocaloric performances of shape memory alloys through comparing with natural rubber
The elastocaloric (eC) effects of natural rubber (NR) and shape memory alloys (SMAs) are compared and potential improvement for eC performances of SMAs is proposed. Both the plateau and hysteresis of stress-strain curve in NR and SMAs are observed. They are attributed to the similar phase transformation: strain-induced...
1606.05319v1
2016-07-18
Windows open for highly tunable magnetostructural phase transitions
An attempt was made to tailor the magnetostructural transitions (MSTs) over a wide temperature range under the principle of isostructural alloying. A series of wide Curie-temperature windows (CTWs) with a maximal width of 377 K between 69 and 446 K were established in the Mn1-yCoyNiGe1-xSix system. Throughout the CTWs,...
1607.05202v1
2016-07-22
Mapping of Electronic Band Gap along the Axis of Single InAs/InSbxAs1-x Heterostructured Nanowire
We report the graded electronic band gap along the axis of individual heterostructured WZ-ZB InAs/InSb0.12As0.88 nanowires. Resonance Raman imaging has been exploited to map the axial variation in the second excitation gap energy (E1) at the high symmetry point (L point) of the Brillouin zone. We relate the origin of t...
1607.06570v1
2016-07-25
DNA-stabilized Ag-Au bimetallic clusters: The effects of alloying and embedding on optical properties
Global geometry optimization and time-dependent density functional theory calculations have been used to study the structural evolution and optical properties of (AgAu)n (n=2-6) nanoalloys both as individual clusters and as clusters stabilized with the fragments of DNA of different size. We show that alloying can be us...
1607.07192v1