A5030202947- Muon and positron interactions and applications
- Aluminum Alloys Composites Properties
- Microstructure and mechanical properties
- Copper Interconnects and Reliability
- Ammonia Synthesis and Nitrogen Reduction
- Magnesium Alloys: Properties and Applications
- Hydrogen Storage and Materials
- ZnO doping and properties
- Nuclear physics research studies
- Nuclear Physics and Applications
- Fusion materials and technologies
- Atomic and Molecular Physics
- Metallic Glasses and Amorphous Alloys
- Advanced ceramic materials synthesis
- Graphene research and applications
- Metal and Thin Film Mechanics
- Intermetallics and Advanced Alloy Properties
- Plasma Diagnostics and Applications
- Copper-based nanomaterials and applications
- Aluminum Alloy Microstructure Properties
- Chemical Synthesis and Characterization
- Advancements in Battery Materials
- MXene and MAX Phase Materials
- Advanced materials and composites
- Particle accelerators and beam dynamics
Charles University
2012-2021
Czech Technical University in Prague
1987-2010
Université des Sciences et de la Technologie d'Oran Mohamed Boudiaf
2004
Institute of Materials and Machine Mechanics of the Slovak Academy of Sciences
1994
Slovak Academy of Sciences
1994
Joint Institute for Nuclear Research
1979-1991
University of Jyväskylä
1989
Institute for Nuclear Research
1983
Czech Academy of Sciences, Nuclear Physics Institute
1969
Combining photoluminescence and positron annihilation studies of hydrothermally grown ZnO crystals with stoichiometry varied by controlled annealing enabled us to clarify the origin green luminescence. It was found that luminescence in has multiple origins consists a band at 2.3(1) eV due recombination electrons conduction zinc vacancy acceptors coupled hydrogen 2.47(2) related oxygen vacancies. The as-grown contain vacancies associated exhibit eV. Annealing Zn vapor removed introduced This...
A systematic study of various, nominally undoped ZnO single crystals, either hydrothermally grown (HTG) or melt (MG), has been performed. The crystal quality assessed by x-ray diffraction, and a comprehensive estimation the detailed impurity hydrogen contents inductively coupled plasma mass spectrometry nuclear reaction analysis, respectively, made also. High precision positron lifetime experiments show that is observed in all crystals investigated, which clusters at 180--182 ps 165--167 for...
Thermal stability of ultrafine grained (mean grain size 150 nm) copper prepared by high pressure torsion was studied means positron-lifetime spectroscopy correlated with transmission electron microscopy. The microstructure the material is strongly inhomogeneous. interiors low dislocation density are separated distorted regions number dislocations. We have found that positrons trapped at dislocations inside and in microvoids situated grains. Calculations lifetime a positron microvoid as...
The main objective of the present paper is to communicate a study defects behavior in zirconia-based nanomaterials---pressure-compacted yttria-stabilized zirconia (YSZ) nanopowders with different contents ${\text{Y}}_{2}{\text{O}}_{3}$ and ceramics obtained by sintering YZS nanopowders. In addition, single crystals were also investigated. Positron annihilation techniques including positron lifetime coincidence Doppler broadening conventional source experiments on monoenergetic beam involved...
Our aim in the present work was to investigate changes of defect structure bulk niobium induced by hydrogen loading. The evolution microstructure with increasing concentration studied x-ray diffraction and two complementary techniques positron annihilation spectroscopy (PAS), namely lifetime slow implantation measurement Doppler broadening, defect-free Nb $(99.9%)$ containing a remarkable number dislocations. These samples were electrochemically loaded up...
Severe plastic deformation of metals introduces not only dislocations, but also a high concentration vacancies. In the present work we employed positron lifetime spectroscopy for investigation deformation-induced vacancies in ultra fine grained prepared by pressure torsion. It was found that all studied agglomerate into small vacancy clusters. Experimental results were combined with ab-initio theoretical calculations parameters clusters various sizes. This new approach described this paper...
Various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. The content in the is determined by nuclear reaction analysis and it found that already 0.3at.% H exists chemically bound form virgin crystals. A single positron lifetime 182ps detected attributed to saturated trapping at Zn vacancies surrounded atoms. It demonstrated a very high amount (up ∼30at.%) can be introduced into electrochemical doping. More than half this...
The aim of the present work was to investigate microstructure bulk niobium irradiated by 10 MeV electrons. Positron-annihilation spectroscopy employed as a principal technique for characterization irradiation-induced defects. Experimental results were compared first-principles theoretical calculations positron characteristics. In addition extended positron-annihilation studies, specimens characterized also x-ray diffraction. It found that vacancies are surrounded hydrogen. Complexes...
Abstract Thermal effects on the microstructure and precipitation in Mg–10wt%Gd alloy were studied this work. The role of lattice defects was investigated using positron annihilation spectroscopy. Studies by combined with X‐ray diffraction microhardness measurements. Vacancies bound to Gd atoms found homogenised sample quenched down room temperature. Subsequently, clustering takes place increasing Gd‐rich clusters represent precursors for further precipitates β ″ phase. formation fine phase...
We have studied low-spin states of 150,152,154,156Gd by nuclear orientation β-decaying Tb in a Gd host. Especially means multipole mixing ratios, including E0/E2, we checked and revised spin-parities assignments to (quasi) rotational ground, β γ bands. For 150Gd propose the new interpretation 1207.2 keV (0β+), 1518.5 (2β+), 1700.1 (4β+), 1430.5 (2γ+), 1988.0 (3γ+), 2080.0 (4γ+). 152,154,156Gd find agreement with recent literature. Our comparison theory includes available data on 158,160Gd up...