Hydrogen Trapping in bcc Iron

Fundamental understanding of H localization in steel is an important step towards theoretical descriptions of hydrogen embrittlement mechanisms at the atomic level. In this paper, we investigate the interaction between atomic H and defects in ferromagnetic body-centered cubic (bcc) iron using density functional theory (DFT) calculations. Hydrogen trapping profiles in the bulk lattice, at vacancies, dislocations and grain boundaries (GBs) are calculated and used to evaluate the concentrations of H at these defects as a function of temperature. The results on H-trapping at GBs enable further investigating H-enhanced decohesion at GBs in Fe. A hierarchy map of trapping energies associated with the most common crystal lattice defects is presented and the most attractive H-trapping sites are identified.

The Important Questions of Statistical Theory of the Crystals' Thermal and Kinetics Properties

In this paper, the short algorithmic formulas for computations of the crystals thermal and kinetic properties are given. These formulas are fulfilled the case of isotropic crystals for any one of dispersion laws of current carriers, where these carriers can be scattered by all kinds of the crystal lattice defects. In the paper, these algorithmic formulas were used to calculations the important properties of crystals with the nonparabolic Kane’s dispersion law of current carriers. Here, the passing from these non-parabolic dispersion law crystals to the parabolic dispersion law crystals was also described.

Сравнительный анализ люминесценции слоев Ge : Sb, выращенных на подложках Ge(001) и Si(001)

Comparative studies of the luminescent properties of Sb doped Ge layers grown on Si (001) and Ge (001) substrates have been carried out. It is shown that in Ge:Sb/Ge(001) layers, in contrast to the Ge:Sb layers grown on silicon, indirect optical transitions make a significant contribution to the photoluminescence signal. This fact is associated with a longer lifetime of charge carriers in homoepitaxial Ge:Sb/Ge structures due to the absence of crystal lattice defects associated with the relaxation of elastic strain. It is shown that the significant increase in the contribution of direct optical transitions to the total photoluminescence signal observed at higher doping levels of Ge:Sb/Ge(001) layers is caused by an increase in the population of electronic states in the Г valley. The luminescent properties of Ge:Sb/Ge(001) and Ge:Sb/Si(001) layers with Sb concentration significantly exceeding its equilibrium solubility are strongly affected by the nonradiative recombination centers, which may be clusters of impurity atoms.