Simulation of Positron Characteristics in Nanocryartalline Materials

Abstract

The theoretical calculations of the position response to different types of defects can be very helpful in order to interpret properly positron measurements. In this contribution a new computational technique to determine position properties in nanocrystalline materials is presented. In such calculations we employ the realistic models of n-materials obtained using molecular dynamics. The new technique is based on the so-called atomic superposition method where atomic densities are superimposed in a selected region of the model (virtual) sample to approxiamte the electron density of the system. We study the virtual samples of n-Cu, n-NiAl, and n-Ni₃Al, for which we calculate position lifetime and position binding energies corresponding to defects located in selected regions of the samples. The regions of interest for position calculations comprise grain boundaries inculding triple points, nano-voids, and bulk-like regions.