Impact of N on the Stacking Fault Energy and Phase Stability of FCC CrMnFeCoNi: An Ab Initio Study

Interstitial alloying has become an important pillar in tuning and improving the materials properties of high-entropy alloys, e.g., enabling interstitial solid-solution hardening and for tuning the stacking fault energies. In this work we performed ab initio calculations to evaluate the impact of interstitial alloying with nitrogen on the fcc...

Self healing of radiation-induced damage in Fe–Au and Fe–Cu alloys: Combining positron annihilation spectroscopy with TEM and ab initio calculations

Self healing of early stage radiation damage by site selective solute segregation is a promising approach to extend the lifetime of nuclear reactor components. In the present study, the creation and autonomous healing of irradiation-induced damage is investigated in pure Fe and high purity Fe–Au and Fe–Cu model alloys. To create radiation...

Positron Annihilation Studies on Thin Film Solar Cells: CdSe and PbSe Quantum Dot Thin Films and Cu(In1-xGax)Se2 Layered Systems

High efficiency, low cost, and long stability are three key factors for the wide application of photovoltaics (PV) which are currently intensively studied in order to meet the increasing global renewable energy demand. Currently, the PV market is mainly based on silicon. However, solar cells based on silicon may not be capable to meet the long...

Ultrastrong medium-entropy single-phase alloys designed via severe lattice distortion

Severe lattice distortion is a core effect in the design of multiprincipal element alloys with the aim to enhance yield strength, a key indicator in structural engineering. Yet, the yield strength values of medium- and high-entropy alloys investigated so far do not substantially exceed those of conventional alloys owing to the insufficient...

Stability, local structure and electronic properties of borane radicals on the Si(100) 2x1:H surface: A first-principles study

Abstract Deposition of a thin B layer via decomposition of B2H6 on Si (PureB process) produces B-Si junctions which exhibit unique electronic and optical properties. Here we present the results of our systematic first-principles study of BHn (n=0-3) radicals on Si(100)2x1:H surfaces, the initial stage of the PureB process. The calculations...

Applicability of the wide-band limit in DFT-based molecular transport calculations

Transport properties of molecular junctions are notoriously expensive to calculate with ab initio methods, primarily due to the semi-infinite electrodes. This has led to the introduction of different approximation schemes for the electrodes. For the most popular metals used in experiments, such as gold, the wide-band limit (WBL) is a...

Thermal Stability of MgyTi1-y Thin Films Investigated by Positron Annihilation Spectroscopy

Mg-Ti compounds are attractive candidates as hydrogen storage materials for their fast sorption kinetics and high storage capacity. In this context, an investigation of their thermal stability is of great importance. The thermal stability of MgyTi1-y thin films was investigated using positron annihilation spectroscopy. Despite the positive...

Hydrogen vacancies facilitate hydrogen transport kinetics in sodium hydride nanocrystallites

We report ab initio calculations based on density-functional theory, of the vacancy-mediated hydrogen migration energy in bulk NaH and near the NaH(001) surface. The estimated rate of the vacancy mediated hydrogen transport, obtained within a hopping diffusion model, is consistent with the reaction rates of H-D exchange in nano-NaH at the...

Electron-capture decay rate of 7Be@C60 by first-principles calculations based on density functional theory

Carrying out a first-principles calculation assuming linear relationship between the electron density at Be nucleus and the electron-capture (EC) decay rate, we explained why 7Be@C60 shows higher EC decay rate than 7Be crystal, which was originally found experimentally by Ohtsuki et al. [Phys. Rev. Lett. 93, 112501 (2004)]. From the results of...

Ab Initio Calculations in Scintillator Research

The optical characteristics of the Ce3+ ion are largely determined by the geometry of the direct environment of the cerium-ion, and are often very sensitive to changes in this environment. These changes are for example periodic changes because of thermal movements of the atoms in the grid, but also because of static changes such as an optical...

The vibrational spectrum of solid ferrocene by inelastic neutron scattering

We calculate the spectrum of internal vibrations of a single ferrocene Fe(C5H5)2 molecule using ab initio density functional theory (without free parameters) and compare this with inelastic neutron scattering data on ferrocene in the solid state at 28 K. Due to the good agreement, we can assign each vibrational mode to each observed peak in the...