scholarly journals Free energy of defect formation: Thermodynamics of anion Frenkel pairs in indium oxide

2011 ◽  
Vol 83 (22) ◽  
Author(s):  
Aron Walsh ◽  
Alexey A. Sokol ◽  
C. Richard A. Catlow
Keyword(s):  
Free Energy ◽  
Indium Oxide ◽  
Defect Formation ◽  
Formation Thermodynamics

Heteroepitaxial Layer Morphology and Misfit Defect Formation

1995 ◽  
Vol 399 ◽  
Author(s):  
A.G. Cullis
Keyword(s):  
Free Energy ◽  
Misfit Dislocation ◽  
Defect Formation ◽  
Elastic Stress ◽  
Stress Relief ◽  
Misfit Strain ◽  
Theoretical Modelling ◽  
Initial Growth ◽  
Dislocation Source ◽  
Heteroepitaxial Layers

ABSTRACTThe manner in which misfit strain can influence the morphology of heteroepitaxial layers is reviewed. Following a brief consideration of theoretical modelling, examples of experimental observations for two important materials systems, SiGe/Si and InGaAs/GaAs, are given. It is demonstrated that the formation of undulations of specific types is driven by partial elastic stress-relief and a lowering of the system free energy. Under these conditions, islands of deposit can be formed during initial growth and ripples can be produced upon continuous layers. Furthermore, the presence of surface morphological distortions and the accompanying strain fluctuations also can have a significant impact upon misfit dislocation introduction. Relationships between these fluctuations and dislocation source behaviour are described.

Entropy of Nanostructures

2017 ◽  
pp. 600-614
Author(s):  
Ottorino Ori ◽  
Franco Cataldo ◽  
Mihai V. Putz
Keyword(s):  
Mechanical Properties ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Defect Formation ◽  
Vacancy Concentration ◽  
Structural Evolution ◽  
Point Of View ◽  
Structural Defects ◽  
Formation Mechanisms ◽  
Topological Invariants

Recent advances in graphene studies deal with the influence of structural defects on graphene chemical, electrical, magnetic and mechanical properties. Here the complex mechanisms leading to the formation of clusters of vacancies in 2D honeycomb HD lattices are described by a pure topological point of view, aiming to correlate the variation of specific topological invariants, sensible to vacancy concentration, to the structural evolution of the defective networks driven by the topo-thermodynamical Gibbs free energy. Interesting predictions on defect formation mechanisms add details on the topological mechanisms featured by the graphenic structures with defects. Future roles of bondonic particles in defective HD materials are also envisaged.

Native Point Defect Densities and Dark Line Defects in ZnSe

1995 ◽  
Vol 408 ◽  
Author(s):  
M. A. Berding ◽  
A. Sher ◽  
M. Van Schilfgaarde
Keyword(s):  
Free Energy ◽  
Point Defect ◽  
Defect Formation ◽  
Local Density ◽  
Full Potential ◽  
Nonradiative Recombination ◽  
Dark Line ◽  
Frenkel Defect ◽  
Native Point Defect ◽  
Defect Densities

AbstractNative point defect densities (including vacancies, antisites and interstitials) in ZnSe are calculated using a quasichemical formalism, including both vibrational and electronic contributions to the defect free energy. The electronic contribution to the defect formation free energy is calculated using the self-consistent first-principles full-potential linearized muffin-tin orbital (FP-LMTO) method and the local-density approximation (LDA). Gradient corrections are included so that absolute reference to zinc atoms in the vapor phase can be made. We find that the Frenkel defect formation energy is ∼0.3 eV lower at a stacking fault than in the bulk lattice. Nonradiative-recombination-induced Frenkel defect generation at stacking faults is proposed as a mechanism responsible for the limited device lifetimes.

scholarly journals On assessing the accuracy of defect free energy computations

2018 ◽  
Vol 52 (4) ◽  
pp. 1315-1352 ◽  
Author(s):  
Matthew Dobson ◽  
Manh Hong Duong ◽  
Christoph Ortner
Keyword(s):  
Free Energy ◽  
Error Analysis ◽  
Numerical Simulations ◽  
Rate Of Convergence ◽  
Defect Formation ◽  
Computational Cost ◽  
Coarse Graining ◽  
Coarse Grained ◽  
One Dimensional ◽  
Rigorous Error

We develop a rigorous error analysis for coarse-graining of defect-formation free energy. For a one-dimensional constrained atomistic system, we establish the thermodynamic limit of the defect-formation free energy and obtain explicitly the rate of convergence. We then construct a sequence of coarse-grained energies with the same rate but significantly reduced computational cost. We illustrate our analytical results through explicit computations for the case of harmonic potentials and through numerical simulations.

scholarly journals Molecular Level Understanding of the Free Energy Landscape in Early Stages of MOF Nucleation

2018 ◽  
Author(s):  
Loukas Kollias ◽  
David C. Cantu ◽  
Marcus A. Tubbs ◽  
Roger Rousseau ◽  
Vassiliki-Alexandra Glezakou ◽  
...  
Keyword(s):  
Free Energy ◽  
Defect Formation ◽  
Dimethyl Formamide ◽  
Salt Bridges ◽  
Enhanced Sampling ◽  
Materials Synthesis ◽  
Early Stages ◽  
Assembly Mechanism ◽  
Secondary Building Units ◽  
Molecular Dynamics Methods

<div><div><div><p>The assembly mechanism of hierarchical materials controlled by the choice of solvent and presence of spectator ions. In this paper, we use enhanced sampling molecular dynamics methods to investigate these effects on the configurational landscape of metal-linker interactions in the early stages of synthesis, using MIL-101(Cr) as a prototypical example. Microsecond-long well-tempered metadynamics (WTmetaD) simulations uncover a complex free energy structural landscape, with distinct crystal (C) and non-crystal (NC) like configurations and their equilibrium population. In presence of ions (Na+, F-), we observe a complex effect on the crystallinity of secondary building units (SBUs), by encouraging/suppressing salt bridges between C configurations and consequently controlling the percentage of defects. Solvent effects are assessed by introducing N, N dimethyl formamide (DMF) instead of water, where SBU adducts are appreciably more stable and compact. These results shed light on how solvent and ionic strength impact the free energy of assembly phenomena that ultimately control materials synthesis and defect formation.</p></div></div></div>

The Effects of Surface Modifications on Tin-Doped Indium Oxide Films: Optoelectrical, Wettability and XPS Investigations

2008 ◽  
Vol 373-374 ◽  
pp. 718-721
Author(s):  
Zhi You Zhong ◽  
Feng Lou Sun
Keyword(s):  
Free Energy ◽  
Sheet Resistance ◽  
Surface Properties ◽  
Surface Free Energy ◽  
Indium Oxide ◽  
Photoelectron Spectroscopy ◽  
Surface Modifications ◽  
Optical Transmittance ◽  
Contact Angles ◽  
Oxygen Plasma Treatment

Surface modifications were performed on the tin-doped indium oxide (ITO) substrates for optoelectronic devices, using the different processing techniques. The effects of modification methods on the surface properties of ITO substrates were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), ultraviolet-visible (UV-vis) spectrophotometer, standard goniometry and four-probe meter, respectively. The surface free energy as the sum of the dispersion and polar components was evaluated from the measured contact angles using the Owens-Wendt approach. Experimental results demonstrate that except the optical transmittance of the ITO, the surface properties including the stoichiometry, morphology, wettability and sheet resistance of the ITO substrates strongly depend on the modification methods. Compared with the other treatments, the oxygen plasma treatment increases the oxygen concentration and decreases the carbon concentration, reduces the surface roughness and the sheet resistance, and enhances the surface free energy and the polarity, and thereby more effectively improves the surface properties of ITO substrates.

Encultured minds, not error reduction minds

2020 ◽  
Vol 43 ◽  
Author(s):  
Robert Mirski ◽  
Mark H. Bickhard ◽  
David Eck ◽  
Arkadiusz Gut
Keyword(s):  
Free Energy ◽  
Error Reduction ◽  
Energy Principle ◽  
Free Energy Principle ◽  
Current Article

Abstract There are serious theoretical problems with the free-energy principle model, which are shown in the current article. We discuss the proposed model's inability to account for culturally emergent normativities, and point out the foundational issues that we claim this inability stems from.

Xenon ion irradiation of superconducting YBa2Cu3O7 thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 92-93
Author(s):  
H. Watanabe ◽  
B. Kabius ◽  
B. Roas ◽  
K. Urban
Keyword(s):  
Defect Formation ◽  
Ion Irradiation ◽  
High Resolution Electron Microscopy ◽  
Structural Disorder ◽  
Flux Lines ◽  
Pinning Effect ◽  
Magnetic Flux Lines ◽  
Resolution Electron ◽  
Radiation Induced ◽  
Induced Defects

Recently it was reported that the critical current density(Jc) of YBa2Cu2O7, in the presence of magnetic field, is enhanced by ion irradiation. The enhancement is thought to be due to the pinning of the magnetic flux lines by radiation-induced defects or by structural disorder. The aim of the present study was to understand the fundamental mechanisms of the defect formation in association with the pinning effect in YBa2Cu3O7 by means of high-resolution electron microscopy(HRTEM).The YBa2Cu3O7 specimens were prepared by laser ablation in an insitu process. During deposition, a substrate temperature and oxygen atmosphere were kept at about 1073 K and 0.4 mbar, respectively. In this way high quality epitaxially films can be obtained with the caxis parallel to the <100 > SrTiO3 substrate normal. The specimens were irradiated at a temperature of 77 K with 173 MeV Xe ions up to a dose of 3.0 × 1016 m−2.

Effects of dopant concentration on the microstructure of tin- doped indium oxide thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 716-717
Author(s):  
I. A. Rauf
Keyword(s):  
Thin Films ◽  
Indium Oxide ◽  
Ionic Radius ◽  
Free Carrier ◽  
Electron Gun ◽  
Periodic Lattice ◽  
Oxide Thin Films ◽  
Transmission Electron ◽  
The Difference ◽  
Dopant Atoms

To understand the electronic conduction mechanism in Sn-doped indium oxide thin films, it is important to study the effect of dopant atoms on the neighbouring indium oxide lattice. Ideally Sn is a substitutional dopant at random indium sites. The difference in valence (Sn4+ replaces In3+) requires that an extra electron is donated to the lattice and thus contributes to the free carrier density. But since Sn is an adjacent member of the same row in the periodic table, the difference in the ionic radius (In3+: 0.218 nm; Sn4+: 0.205 nm) will introduce a strain in the indium oxide lattice. Free carrier electron waves will no longer see a perfect periodic lattice and will be scattered, resulting in the reduction of free carrier mobility, which will lower the electrical conductivity (an undesirable effect in most applications).One of the main objectives of the present investigation is to understand the effects of the strain (produced by difference in the ionic radius) on the microstructure of the indium oxide lattice when the doping level is increased to give high carrier densities. Sn-doped indium oxide thin films were prepared with four different concentrations: 9, 10, 11 and 12 mol. % of SnO2 in the starting material. All the samples were prepared at an oxygen partial pressure of 0.067 Pa and a substrate temperature of 250°C using an Edwards 306 coating unit with an electron gun attachment for heating the crucible. These deposition conditions have been found to give optimum electrical properties in Sn-doped indium oxide films. A JEOL 2000EX transmission electron microscope was used to investigate the specimen microstructure.

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