In situ 64Cu Doppler-broadening positron-annihilation methods for elevated temperature study of defect formation in metals

1995 ◽  
Vol 73 (1-2) ◽  
pp. 11-17 ◽  
Author(s):  
D. W. Lawther ◽  
R. A. Dunlap
Keyword(s):  
Electrical Resistivity ◽  
Elevated Temperature ◽  
Positron Annihilation ◽  
Defect Structure ◽  
Elevated Temperatures ◽  
Defect Formation ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Spectroscopy Experiment

A Doppler-broadening positron-annihilation-spectroscopy experiment that utilizes an in situ 64Cu source for the study of Cu and Cu-containing materials is described. This technique is particularly useful for the investigation of defect structure at elevated temperatures, and the present instrumentation provides reliable results up to about 1000 °C. The method described is applicable to Cu-containing samples with as little as about 0.1 at.% Cu. Results from measurements on a single crystal of elemental Cu are compared with literature results obtained using other positron-annihilation methods and electrical-resistivity studies.

scholarly journals Source for In Situ Positron Annihilation Spectroscopy of Thermal—And Hydrogen-Induced Defects Based on the Cu-64 Isotope

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6693
Author(s):  
Iurii Bordulev ◽  
Roman Laptev ◽  
Denis Kabanov ◽  
Ivan Ushakov ◽  
Viktor Kudiiarov ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Defect Structure ◽  
Nuclear Reactor ◽  
Positron Annihilation Spectroscopy ◽  
Hydrogen Atmosphere ◽  
Positron Source ◽  
Hydrogen Saturation ◽  
Research Nuclear Reactor ◽  
Induced Defects

This work aims to investigate the 64Cu isotope applicability for positron annihilation experiments in in situ mode. We determined appropriate characteristics of this isotope for defect studies and implemented them under aggressive conditions (i.e., elevated temperature, hydrogen environment) in situ to determine the sensitivity of this approach to thermal vacancies and hydrogen-induced defects investigation. Titanium samples were used as test materials. The source was obtained by the activation of copper foil in the thermal neutron flux of a research nuclear reactor. Main spectrometric characteristics (e.g., the total number of counts, fraction of good signals, peak-to-noise ratio) of this source, as well as line-shaped parameters of the Doppler broadening spectrum (DBS), were studied experimentally. These characteristics for 64Cu (in contrast to positron sources with longer half-life) were shown to vary strongly with time, owing to the rapidly changing activity. These changes are predictable and should be considered in the analysis of experimental data to reveal information about the defect structure. The investigation of samples with a controlled density of defects revealed the suitability of 64Cu positron source with an activity of 2–40 MBq for defects studies by DBS. However, greater isotope activity could also be applied. The results of testing this source at high temperatures and in hydrogen atmosphere showed its suitability to thermal vacancies and hydrogen-induced defects studies in situ. The greatest changes in the defect structure of titanium alloy during high-temperature hydrogen saturation occurred at the cooling stage, when the formation of hydrides began, and were associated with an increase in the dislocation density.

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

The Evolution Behavior of Defects in the Nanofilms of W/Cu and W Probed by Doppler Broadening Positron Annihilation Spectroscopy

2017 ◽  
Vol 373 ◽  
pp. 104-107
Author(s):  
Ling Wang ◽  
Ai Hong Deng ◽  
Kang Wang ◽  
Yong Wang ◽  
Xiao Bo Lu ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Storage Time ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Radio Frequency Magnetron Sputtering ◽  
Helium Ions ◽  
Near Surface ◽  
Evolution Behavior

W/Cu multilayer nanofilms and pure W nanofilms were prepared in pure Ar and He/Ar mixing atmosphere by radio frequency magnetron sputtering method. The defect evolution of the samples was characterized by Doppler broadening positron annihilation spectroscopy (DB-PAS).The results show that plenty of defects can be produced by introducing helium (He) into W/Cu multilayer nanofilms. With the natural storage time increasing, the helium located in the near surface of W/Cu multilayer nanofilm would be released gradually and induce the coalescence of the helium related defects due to the diffusion of the helium and defects. In addition, the pure W nanofilms were irradiated by 30 keV helium ions and 40 keV hydrogen (H) ions in sequence at room temperature. From the DB-PAS analysis, it can be shown that a large number of vacancy-type defects are produced due to the He and/or H irradiation. H ions would be trapped by He related defects and produced He-H-V complexes.

scholarly journals Photochromic YOxHy Thin Films Examined by in situ Positron Annihilation Spectroscopy

2020 ◽  
Vol 137 (2) ◽  
pp. 205-208 ◽  
Author(s):  
S.W.H. Eijt ◽  
T.W.H. de Krom ◽  
D. Chaykina ◽  
H. Schut ◽  
G. Colombi ◽  
...  
Keyword(s):  
Thin Films ◽  
Positron Annihilation ◽  
Positron Annihilation Spectroscopy

Investigation of Defects Accumulation in the Process of Hydrogen Sorption and Desorption

2015 ◽  
Vol 1085 ◽  
pp. 328-334 ◽  
Author(s):  
Andrey M. Lider ◽  
Olga V. Husaeva ◽  
Yuriy S. Bordulev ◽  
Roman S. Laptev ◽  
Viktor N. Kudiiarov
Keyword(s):  
Positron Annihilation ◽  
Gas Phase ◽  
Defect Structure ◽  
Positron Lifetime ◽  
Pure Titanium ◽  
Structure Study ◽  
Hydrogen Sorption ◽  
Doppler Broadening ◽  
Commercially Pure Titanium ◽  
Commercially Pure

This paper is devoted to the defect structure study of commercially pure titanium after hydrogen sorption-desorption cycles by means of positron lifetime (PL) and Doppler broadening spectrometry. Material was loaded with hydrogen from the gas phase till the concentration of hydrogen reached the value of 0.05 wt.% for each cycle. The essential changes in the positron annihilation characteristics of the sample are occurred after the each stage of treatment.

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