Defect evolution during annealing of deformed FeSi alloys studied by positron annihilation spectroscopy

High silicon steel is widely used in electrical appliances. Alloying iron with silicon improves its magnetic performance. A silicon content up to 6.5 wt. % gives excellent magnetic properties such as high saturation magnetization, near zero magnetostriction and low iron loss in high frequencies. Their workability is greatly reduced by the...

Electronic coupling of colloidal CdSe nanocrystals monitored by thin-film positron-electron momentum density methods

The effect of temperature controlled annealing on the confined valence electron states in CdSe nanocrystal arrays, deposited as thin films, was studied using two-dimensional angular correlation of annihilation radiation. A reduction in the intensity by ?35% was observed in a feature of the positron annihilation spectrum upon removal of the...

Positron depth profiling of the structural and electronic structure transformations of hydrogenated Mg-based thin films

We report positron depth-profiling studies on the hydrogen sorption behavior and phase evolution of Mg-based thin films. We show that the main changes in the depth profiles resulting from the hydrogenation to the respective metal hydrides are related to a clear broadening in the observed electron momentum densities in both Mg and Mg2Ni films....

Amorphous-amorphous transition in glassy polymers subjected to cold rolling studied by means of positron annihilation lifetime spectroscopy

In this study, polycarbonate (PC) and polystyrene (PS) are subjected to plastic deformation by means of cold rolling and the resulting variation of the free volume and its subsequent time evolution after rolling is investigated by means of positron annihilation lifetime spectroscopy (PALS). The value of the long lifetime component that is...

Nanosystems in Ceramic Oxides Created by Means of Ion Implantation

The material properties of nanometer-sized clusters are dependent on the cluster size. Changing the cluster dimensions induces structural phase transformations, metal-insulator transitions, non-linear optical properties and widening of the band gap of semiconductors. In this work, nanoclusters are created by ion implantation followed by thermal...

Positrons and positronium for polymer thin film analysis

Hydrogen interactions with silicon-on-insulator materials

The booming of microelectronics in recent decades has been made possible by the excellent properties of the Si/SiO2 interface in oxide on silicon systems.. This semiconductor/insulator combination has proven to be of great value for the semiconductor industry. It has made it possible to continuously increase the number of transistors per chip...

The Delft intense slow positron beam 2D-ACAR facility for analysis of nanocavities and quantum dots

Positron annihilation spectroscopy is a powerful method to study materials containing very small concentrations of atomic defects and embedded quantum dots. Depending on the method of producing positrons, there are bulk spectroscopies using fast positrons and depth profiling spectroscopies using slow positrons. Both types of spectroscopies are...

Trapping of nitrogen at the Fe-AlN precipitate interface studied by the positron Doppler broadening technique

Precipitation of Silicon in a Solid Quenched Aluminium- ilicon (1.3 at yo) Alloy Studied by Positron Annihilation

Doppler broadening of the positron annihilation line was measured for quenched and aged specimens of an aluminium-silicon (1.29 at%Si) alloy. One set of specimens was aged at room temperature (set A) and one set was isochronally (t = 30 min) aged at temperatures ranging from 347 to 884 K (set B). The lineshape parameter S measured in the as...