An Investigation of Point Defects in NiAl Using Positron Annihilation Techniques

1998 ◽  
Vol 552 ◽  
Author(s):  
Werner Puff ◽  
Bernd Logar ◽  
Adam G. Balogh
Keyword(s):  
Positron Annihilation ◽  
Point Defects ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Composition Range ◽  
Isochronal Annealing ◽  
Doppler Broadening ◽  
Positron Lifetime Spectroscopy ◽  
Induced Defects

ABSTRACTVacancy-like defects in NiAl in the composition range 47 at.-% < CNi < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. Isochronal annealing of samples quenched at 1600°C and after proton irradiation show that the induced defects are quite different.

Proton Irradiation Induced Defects in 611- and 4H-SiC

1998 ◽  
Vol 540 ◽  
Author(s):  
Werner Puff ◽  
Adam G. Balogh ◽  
Peter Mascher
Keyword(s):  
Proton Irradiation ◽  
Positron Lifetime ◽  
Doppler Broadening ◽  
Defect Complexes ◽  
Radiation Induced ◽  
Positron Lifetime Spectroscopy ◽  
Induced Defects ◽  
Irradiation Induced Defects ◽  
Type Sample

AbstractAnnealing of defects in proton irradiated bulk n-type 6H- and semi-insulating 4H-SiC has been investigated by positron lifetime spectroscopy and Doppler-broadening measurements. For the n-type sample radiation induced defects in dependence of the proton fluence were studied. Three or four annealing stages were found, during which the formation of larger defect complexes could be observed.

Radiation-Induced Defects in Electron and Proton Irradiated ZnS

1998 ◽  
Vol 540 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A.G. Balogh
Keyword(s):  
Vapour Deposition ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Chemical Vapour ◽  
Isochronal Annealing ◽  
Doppler Broadening ◽  
Defect Complexes ◽  
Radiation Induced ◽  
The Stability ◽  
Induced Defects

AbstractIn this contribution, we present a study aimed at investigating the microstructural changes of ZnS single crystals and CVD (chemical vapour deposition) grown crystals after electron and proton irradiation. Positron lifetime and Doppler-broadening measurements were performed to investigate the stability of the radiation induced defects and possible clustering mechanisms during isochronal annealing. After electron as well as proton irradiation the significant changes in the annihilation characteristics are indications of radiation induced open-volume-type defects. It is found that electron and proton irradiation causes different changes in the positron annihilation characteristics. After electron irradiation a significant defect component is observed which can be attributed to the annihilation in monovacancies. During isochronal annealing agglomerations to divacancy-type defects take place. Proton irradiation reveals a significantly different defect structure. Isochronal annealing causes agglomerations to larger defect complexes. The observed annealing stages are indications of the annealing of variously sized vacancy complexes.

Microstructural Evolution of Radiation Induced Defects In ZnO During Isochronal Annealing

1998 ◽  
Vol 540 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A.G. Balogh
Keyword(s):  
Room Temperature ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Thermal Evolution ◽  
Isochronal Annealing ◽  
Doppler Broadening ◽  
Thermal Dependence ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this study we discuss the microstructural changes after electron and proton irradiation and the thermal evolution of the radiation induced defects during isochronal annealing. The nominally undoped samples were irradiated either with 3 MeV protons to a fluence of 1.2× 1018 p/cm2 or with 1 MeV electrons to a fluence of 1×1018 e/cm2. The investigation was performed with positron lifetime and Doppler-broadening measurements. The measurements were done at room temperature and in some cases down to 10 K to investigate the thermal dependence of the trapping characteristics of the positrons.

Effect of Nature Aging on Positron Lifetime Spectroscopy in Casting and Wrought Al-alloys

2007 ◽  
Vol 265 ◽  
pp. 13-18 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
M. Abdel-Rahman ◽  
N.A. Kamel ◽  
M.S. Abdallah ◽  
Emad A. Badawi
Keyword(s):  
Aluminum Alloys ◽  
Positron Annihilation ◽  
Point Defects ◽  
Positron Lifetime ◽  
Natural Aging ◽  
Al Alloys ◽  
Isochronal Annealing ◽  
Mean Lifetime ◽  
Positron Lifetime Spectroscopy

Positron annihilation has been performed in order to study the isochronal annealing of wrought (2024, 7075) and cast (AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) aluminum alloys, at temperatures ranging from RT to 773K, after having been deformed at RT to 25% deformation. Two annealing stages of the microstructures were distinguished, which were attributed to recovery in (2024, AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) due to point defects and dislocations, respectively, and only one (due to dislocations) in (7075). Also, natural aging for up to more than 650 days was studied as a function of mean lifetime.

A STUDY OF RECOVERY STAGES IN SOME PLASTICALLY DEFORMED ALUMINUM ALLOYS BY POSITRON LIFETIME SPECTROSCOPY

2005 ◽  
Vol 12 (02) ◽  
pp. 203-207 ◽  
Author(s):  
M. A. ABDEL-RAHMAN ◽  
M. S. ABDALLAH ◽  
EMAD A. BADAWI
Keyword(s):  
Aluminum Alloys ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Positron Lifetime ◽  
Isochronal Annealing ◽  
Temperature Range ◽  
Positron Lifetime Spectroscopy

Positron annihilation was performed to study the isochronal annealing of wrought (2024, 7075) and casting ( AlSi 11.35 Mg 0.23, AlSi 10.9 Mg 0.17 Sr 0.06) aluminum alloys in the temperature range from room temperature to 773 K after they had been deformed at room temperature with 25% deformation. Two annealing stages of microstructures were distinguished which were attributed to recovery in 2024, and AlSi 11.35 Mg 0.23, AlSi 10.9 Mg 0.17 Sr 0.06 due to point and dislocations respectively, and only one due to dislocations in 7075.

Vacancy-Type Defects in as-Grown and Proton-Irradiated 6H-SiC

1998 ◽  
Vol 512 ◽  
Author(s):  
Werner Puff ◽  
Peter Mascher ◽  
Adam G. Balogh
Keyword(s):  
Positron Lifetime ◽  
Doppler Broadening ◽  
Defect Complexes ◽  
Radiation Induced ◽  
Positron Lifetime Spectroscopy ◽  
P Type ◽  
Induced Defects

ABSTRACTAnnealing of defects in as-grown and proton irradiated bulk n- and p-type 6H-SiC has been investigated by positron lifetime spectroscopy and Doppler-broadening measurements. The grown-in defects do not anneal out until 1600 °C, whereas the radiation induced defects show three main annealing stages well below this temperature. During annealing, the formation of larger defect complexes can be observed.

scholarly journals Vacancies in electron irradiated 6H silicon carbide studied by positron annihilation spectroscopy

2003 ◽  
Vol 792 ◽  
Author(s):  
C. H. Lam ◽  
C. C. Ling ◽  
C. D. Beling ◽  
S. Fung ◽  
H. M. Weng ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Positron Annihilation ◽  
Electron Irradiation ◽  
Room Temperature ◽  
Positron Lifetime ◽  
Positron Annihilation Spectroscopy ◽  
Isochronal Annealing ◽  
Positron Lifetime Spectroscopy ◽  
Irradiation Process ◽  
Positron Lifetime Measurement

ABSTRACTPositron lifetime spectroscopy was employed to study the as-electron-irradiated (10 MeV, 1×1018 cm-2) n-type 6H silicon carbide sample in the measuring temperature range of 15 K to 294 K. Isochronal annealing studies were also performed up to the temperature of 1373 K by carrying out the room temperature positron lifetime measurement. Negatively charged carbon vacancies and VCVSi divacancy were identified as the major vacancy type defects induced by the electron irradiation process. The concentration of the VCVSi divacancy was found to decrease dramatically after the 1973 K annealing.

Point Defect Characterization in CoAl Using Positron Annihilation

1998 ◽  
Vol 552 ◽  
Author(s):  
Werner Puff ◽  
Bernd Logar ◽  
Adam G. Balogh
Keyword(s):  
Point Defect ◽  
Positron Lifetime ◽  
Composition Range ◽  
Defect Characterization ◽  
Doppler Broadening ◽  
Dramatic Decrease ◽  
S Parameter ◽  
Co Concentration ◽  
Long Time ◽  
Positron Lifetime Spectroscopy

ABSTRACTVacancy-like defects in CoAl in the composition range 48.5 at.-% <Cco, < 53 at.-% are investigated by means of positron lifetime spectroscopy and Doppler-broadening measurements. The observed lifetimes in the annealed samples confirm that defects are quenched-in during the production of the samples. The values of the positron lifetime and the S-parameter decrease with increasing Co concentration. After quenching from 1400°C or 1600°C an increase in the positron parameters isobserved. Long-time annealing of the Co-rich sample shows a dramatic decrease of the positron lifetime to the expected bulk lifetime.

Vacancy-Type Defects in Electron and Proton Irradiated II-VI Compounds

1998 ◽  
Vol 510 ◽  
Author(s):  
S. Brunner ◽  
W. Puff ◽  
P. Mascher ◽  
A.G. Balogh
Keyword(s):  
Band Gap ◽  
Proton Irradiation ◽  
Positron Lifetime ◽  
Wide Band ◽  
Compound Semiconductors ◽  
Doppler Broadening ◽  
Wide Band Gap ◽  
Radiation Induced ◽  
Induced Defects ◽  
Mev Protons

AbstractIn this contribution we present a study aimed at comparing results of positron-lifetime and Doppler-broadening measurements on the wide-band-gap compound semiconductors ZnS, ZnSe, and ZnTe. To investigate the basic properties of intrinsic and radiation induced defects the samples were irradiated either with 3 MeV protons or 1 MeV electrons. The isochronal annealing was performed in an Ar atmosphere. It was found that electron and proton irradiation cause different changes in the positron annihilation characteristics. Several annealing stages were observed, related to the annealing of variously sized vacancy complexes.

Study of Compensation Defects and Electron Irradiation-Induced Defects in Undoped SI-InP by Positron Lifetime Spectroscopy

2008 ◽  
Vol 607 ◽  
pp. 134-136
Author(s):  
Y.J. Zhang ◽  
Ai Hong Deng ◽  
You Wen Zhao ◽  
J. Yu ◽  
X.X. Yu ◽  
...  
Keyword(s):  
Electron Irradiation ◽  
Positron Lifetime ◽  
Deep Level ◽  
High Concentration ◽  
Positron Annihilation Lifetime ◽  
Donor Type ◽  
Positron Lifetime Spectroscopy ◽  
Transient Spectroscopy ◽  
Induced Defects ◽  
Irradiation Induced Defects

Positron annihilation lifetime (PAL) spectroscopy，photo-induced current transient spectroscopy (PICTS) and thermally stimulated current (TSC) have been employed to study the formation of compensation defects and their evolvement under iron phosphide (IP) ambience or pure phosphide (PP) ambience. In the formation of IP SI-InP, the diffusion of Fe atoms suppresses the formation of some open-volume defects. As to PP SI-InP, VInH4 complexes dissociate into acceptor vacancies VInHn(n-3)(n=0,1,2,3), which compensate residual donor type defects and make the sample semi-insulating. Electron irradiation-induced deep level defects have been studied by TSC in PP and IP SI-InP, respectively. In contrast to a high concentration of irradiation-induced defects in as-grown and PP annealed InP, IP SI-InP has a very low concentration of defects.

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