We present a careful study of the energetics of vacancy and substitutional impurities in aluminum in both the bulk and small cluster environments. The calculations are done within the framework of the local-densityfunctional formalism and are based on the pseudopotential method with plane-wave expansion and periodic boundary conditions. Both the ionic and electronic degrees of freedom are fully...

To minimize the lattice thermal conductivity in thermoelectrics, strategies typically focus on the scattering of low-frequency phonons by interfaces and high-frequency phonons by point defects. In addition, scattering of mid-frequency phonons by dense dislocations, localized at the grain boundaries, has been shown to reduce the lattice thermal conductivity and improve the thermoelectric perform...

The correlation factor for impurity diffusion by a vacancy-mechanism is a function of the vacancy-jump frequencies in the surroundings of the diffusing atom. Since in Si and Ge the vacancy can act as an acceptor, a long-range Coulomb interaction between donor atoms and vacancies exists. The usual assumption, that only a few vacancy-jump frequencies in the im­ mediate surroundings of the vacancy...

The theory of non radiative electronic transitions is represented in two papers. In the first of these we calculate wavefunctions, energies, matrix-elements etc. In the second we discuss the general reaction mechanism and apply the theory to two examples. The wavefunction of a crystal volume containing one defect is calculated on the base of a microscopic theory. For our numerical discussion we...

Using first-principles calculations, we study the electronic structures of Pt/HfO2 interface in the presence of oxygen vacancy. The energetics and charge transfer are examined when the oxygen vacancy is at various distances from the interface. It is found that the oxygen vacancy is strongly attracted to the interface and the charge transfer decreases monotonically as the vacancy moves away from...

deflection analysis of a simply supported microbeam subjected to a concentrated load at the middle is investigated on the basis of a shear deformable beam theory and non-classical theory. effects of shear deformation and small size are taken into consideration by hyperbolic shear deformable beam theory and modified strain gradient theory, respectively. the governing differential equations and c...

Before starting this module, it is assumed that the student is familiar with the crystalline nature of metals and alloys, and understands the terms interstitial, vacancy, substitutional solid solution, binary alloy. References are made to the equilibrium vacancy concentration and it is preferable that this concept had been encountered, although backup is available both through the glossary and ...

In the present study, the effects of arrangement and distribution of multifarious types of defects on fundamental frequency of carbon nanotubes are investigated with respect to different chirality and boundary conditions. Interatomic interactions between each pair of carbon atoms are modeled using two types of non–linear spring–like elements. To obtain more information about the influences of d...

The modifications and extensions of standard continuum models used for a description of material transport due to electromigration with models for the copper microstucture are studied. Copper grain boundaries and interfaces are modeled as a network of high diffusivity paths. Additionally, grain boundaries act as sites of vacancy recombination. The connection between mechanical stress and materi...

The electronic structure of an isolated oxygen vacancy in SrTiO3 has been investigated with a variety of ab initio quantum mechanical approaches. In particular we compared pure density functional theory ~DFT! approaches with the Hartree-Fock method, and with hybrid methods where the exchange term is treated in a mixed way. Both local cluster models and periodic calculations with large supercell...