Visualizing Defect Energetics

The defect formation energy ΔHdef is an important property which relates to off-stoichiometry, electronic dopability and ionic conductivity of the material. The value …

An extended computational approach for point-defect …

approach from defect formation energies based on density functional theory. In this work, calculations of thermal and charge equilibria among point defects are extended to a …

Simulation study on defect formation mechanism of the

The surface quality of SiC particle-reinforced aluminum matrix (SiCp/Al) composite plays an important role in their practical performance. Therefore, an in-depth understanding of the defect formation mechanism paves the solid foundation for the improvement of machined surface quality, which is the prerequisite for the widespread …

Molecular insights into vacancy defect formation in silicon …

The model enables atomic-level observation and tracking of the formation and evolution of vacancy defects in silicon anodes during the heating process induced by femtosecond laser pulses. The results reveal the dynamics of femtosecond laser-induced silicon vacancies, which can be divided into ballistic, combination, and stabilization …

Model of stress-induced defect formation in drying polymer …

This model predicts stress growth and defect formation during drying of such films that remain above their glass transition temperature, so that Fickian difision persists. The stress in the drying gel is taken from mixture theory; the polymer network is a nonlinear elastic or hypoelastic solid, whereas the solvent is an ideal fluid. ...

Defect formation, ordering, and transport in SrFe1–x Si x

Oxygen nonstoichiometry of perovskite-like SrFe1–x Si x O3–δ (x = 0.05–0.20), studied by thermogravimetric analysis and coulometric titration in the oxygen partial pressure range 10−20–0.5 atm at 700–950 °C, decreases with Si4+ additions. The equilibrium p O 2 $$ {p}_{{mat{O}}_2} $$ –T−δ diagrams can be adequately …

Ultrafast formation of topological defects in a two

To understand the mechanism of defect formation at the femtosecond timescale, we use an ultrashort light pulse to create topological defects in a 2D charge density wave (CDW), and we examine their ...

Strain effect on the defect formation and diffusion in Ti2AlC …

In this work, by using a first-principles method, the strain effects on the defect formation and diffusion in Ti 2 AlC and Ti 3 AlC 2 were studied by imposing an equibiaxial in-plane strain along the a and b (denoted as ab) axes. The formation energies of Ti vacancies are substantially larger than those of Al and C vacancies. As the imposed ...

Defect Formation during the Manufacture of Copper Alloy …

The causes promoting the formation of defects on the internal surface of two different copper alloys subjected to cold rolling to fabricate seamless copper tubes are described. Defects characterized by oxide formation and delaminated material were found in various zones along the length of the tubes, leading to crack formation. It was found …

First-principles calculation of intrinsic defect chemistry …

Fermi energy. Formation energy of charged defects (q ≠ 0) is a linear function of the Fermi energy as given in Eq.1.Therefore, the defect formation energies depend on the magnitude of the band ...

Understanding the origin of defect states, their nature, and …

Here, we review and attempt to formulate the rationale for possible types of defect formation and origin of defect core structure that largely deteriorate the 'optoelectronic quality' of perovskite materials and devices.

(PDF) Molecular dynamics studies of defect …

PDF | We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and ([Formula: see... | Find, read and cite all the research you ...

A systematic study of various 2D materials in the light of defect …

To assess the impact of defects, their enthalpies of formation and their signature levels in the density of states have been studied. We find, consistently with literature reports, that chalcogen vacancies are the most likely source of defects. It is shown that while pristine 2D materials are in general stable whenever set in contact with ...

Elucidating the role of pulse shaping on defects formation …

In this paper, we study the effects of shaping the pulsed wave lasers in the time domain on build quality, microstructure, and residual stresses, quantifying the lack of fusion and high-energy spherical pores volume fractions using lab-scale X-ray microtomography, and understanding the concomitant formation of these two types of …

Defect formation in metal–organic frameworks initiated by the …

The defect formation in metal–organic frameworks (MOFs) initiated by the crystal growth-rate of different synthesis procedures affects the structure, morphology and other properties of MOFs such as particle shape, gas adsorption capacity and specifically catalytic performance etc. Although the design of defect structures and the defect ...

The role of cascade energy and temperature in primary defect formation

Subcascade formation begins to have a significant influence on the defect formation for cascade energies above 10 keV. A power-law exponent of 1.12 was obtained for simulations between 20 and 50 keV. Although only a relatively small range of energies could be used to obtain the exponent of 1.12, there are two reasons for believing that the ...

Fundamentals and engineering of defects

Two equilibrium curves of minimum defect concentrations n* = N exp(-E d /kT) with defect formation energies E d = 1 and 2 eV vs. reciprocal temperature 10 3 /T …

Point Defect Formation and Diffusion | SpringerLink

The basic defects (vacancies and interstitials) form the foundation for all observed effects of irradiation on the physical and mechanical properties of materials. …

Point Defect Formation and Diffusion | SpringerLink

2 Thermodynamics of Point Defect Formation. Even in the absence of irradiation, a crystal cannot exist at a finite temperature in a state of absolute perfection. Statistically, there is a finite probability that sufficient energy will be concentrated, by local fluctuations, to form a defect in the crystal lattice.

Understanding the Correlation between the Crystallization …

In this study, deep-trap defects caused by B-site antisites and vacancies are introduced into the double perovskite formamidinium (FA) 1.5 Cs 0.5 AgBi(Cl 0.75 Br 0.25) 6 lattice during crystallization. Remarkably, valeric acid suppresses antisites and facilitates the formation of distinct nanocrystals with a structurally ordered double perovskite.

Reviewing computational studies of defect formation and …

Graphene is composed of sp 2-hybridized carbon atoms in a planar hexagonal configuration with an experimentally determined nearest neighbor C–C distance of 1.42 Å. [28] Although all the atoms in pristine graphene have the same coordination, two different carbon linkages exist, denoted as the zigzag and armchair directions; they are shown …

Formation mechanism of grown-in defects in silicon

Findings reveal that the formation of grown-in defects in silicon depends on v/G values (v: crystal growth rate; G: temperature gradient near the solid/liquid interface) [2]. The present model shows that the complex VaO resolves into a vacancy and an oxygen atom; in other words, it becomes their sink and source between high temperatures in ...

Growth and defect formation mechanism of CVD-prepared …

The growth state of CVD SiC coatings and defect formation causes were obtained to optimize the deposition results. Finally, the effect of CVD SiC under different simulation conditions was confirmed using experiments. On the basis of this, the optimum deposition process conditions were obtained. The present model and simulation strategy …

Defect Formation Mechanisms in Selective Laser …

Abstract Defect formation is a common problem in selective laser melting (SLM). This paper provides a review of defect formation mechanisms in SLM. It sum-marizes the recent research outcomes on defect findings and classification, analyzes formation mechanisms of the common defects, such as porosities, incomplete fusion holes, and …

Influence of Ion Implantation on Silicon Pits Defect Formation …

In this paper a systemic investigation was performed to understand the effect of ion implantation on pits defect formation in the semiconductor fabrication. The pits defect is discovered after hydrofluoric acid etch process by dark or bright field optical inspection (DFI or BFI), whereas cannot be detected after ion implantation. Two typical pits defect …

Generalized Kibble-Zurek mechanism for defects formation …

The Kibble-Zurek (KZ) mechanism has played a fundamental role in defect formation with universal scaling laws in nonequilibrium phase transitions. However, this theory may not accurately predict the scaling laws in inhomogeneous systems and slow quenching processes. Here, we present a generalized KZ mechanism for the defect …

Fluid Flow and Defect Formation in the Three-Dimensional …

Fluid flow within the dendritic structure at the solid–liquid interface in nickel-based superalloys has been studied in two directionally solidified alloy systems. Millimeter-scale, three-dimensional (3D) datasets of dendritic structure have been collected by serial sectioning, and the reconstructed mushy zones have been used as domains for fluid-flow …

Impact of carbon injection in 4H-SiC on defect formation …

The electrically active defects that were created by annealing the C-capped samples were characterized using DLTS and MCTS in the 100 K–600 K temperature range.For DLTS, a reverse bias of − 5 V was applied to the samples followed by sequential pulses to 0 V with a pulse width of 100 ms. The period width was 200 ms or 50 ms.

Molecular dynamics studies of defect formation during

We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and ([Formula: see text]) wurtzite-GaN surfaces. The simulated growths are conducted on an atypically large scale by sequentially injecting nearly a million individual vapor- …

Quick-start guide for first-principles modelling of point defects …

A defect is often referred to according to its spectroscopic signature. An anion vacancy with a trapped electron in an ionic crystal may absorb light in the visible range, making the transparent host material colourful; an F center (Farbe means colour in German). In electrical measurements, such as deep level transient spectroscopy (DLTS), …

Molecular dynamics studies of defect formation during …

We investigate the formation of extended defects during molecular-dynamics (MD) simulations of GaN and InGaN growth on (0001) and (11 2 ¯ 0) wurtzite-GaN surfaces.The simulated growths are conducted on an atypically large scale by sequentially injecting nearly a million individual vapor-phase atoms towards a fixed GaN surface; we …