Electron Irradiated InP: A Positron Annihilation Study

1992 ◽  
Vol 262 ◽  
Author(s):  
T. Bretagnon ◽  
S. Dannefaer ◽  
D. Kerr
Keyword(s):  
Positron Annihilation ◽  
Charge State ◽  
Electron Irradiation ◽  
Positron Lifetime ◽  
Lifetime Measurements ◽  
Positron Annihilation Study

ABSTRACTPositron lifetime measurements show that electron irradiation produces indium vacancy related defects in InP. Divacancies are also found in semi-insulating and lightly doped p and n-type materials. Temperature investigations show a change in the divacancy charge state.

Positron state and Lifetime in C60/C70 Fullerites

1992 ◽  
Vol 270 ◽  
Author(s):  
H.-E. Schaefer ◽  
M. Forster ◽  
R. WÜrschum ◽  
F. Banhart
Keyword(s):  
Electron Microscopy ◽  
Hydrostatic Pressure ◽  
High Resolution ◽  
Positron Annihilation ◽  
Positron Lifetime ◽  
High Resolution Electron Microscopy ◽  
Lattice Defects ◽  
Lifetime Measurements ◽  
Resolution Electron ◽  
Positron State

ABSTRACTThe present paper reports on positron lifetime measurements on Ceo/C 70 fullerite powder as a function of temperature and quasi-hydrostatic pressure in order to give an estimate of the positron annihilation site in the fullerite lattice. A single-component positron lifetime of 402 ps is observed which significantly decreases under quasi-hydrostatic pressure. From this and the soft intermolecular properties of the fullerites one can conclude that the positron is annihilated rather in the intermolecular space than inside the fullerene molecules. However, positron trapping at lattice defects, which are observed by high-resolution electron microscopy, cannot be ruled out.

scholarly journals POSITRON LIFETIME MEASUREMENTS IN NATURAL RUBBER WITH DIFFERENT FILLERS

2013 ◽  
Vol 22 ◽  
pp. 112-117 ◽  
Author(s):  
A. MANDAL ◽  
S. MUKHERJEE ◽  
S. PAN ◽  
A. SENGUPTA
Keyword(s):  
Natural Rubber ◽  
Positron Annihilation ◽  
Free Volume ◽  
Positron Lifetime ◽  
Amorphous Region ◽  
Filler Concentration ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime

Positron annihilation lifetime spectra (PLAS) have been measured for natural rubber polymer with different fillers (Titenium dioxide, Nanosilica and Nanoclay) as a function of filler concentration to investigate how these fillers affect the microstructure of free volume of natural rubber. The lifetime spectra is analyzed by using LT9.0 and the longest lived component(τo-Ps) is attributed to the pick- off annihilation of o-Ps in free volume sites, available mostly in the amorphous region of polymer. On the basis of the τo-Ps values the radii of the free volume holes (Rh) are calculated. The PALS results show that o-Ps lifetime as well as the size of free volume decreases with the increase of filler concentration.

scholarly journals A positron annihilation study of defect accumulation in phosphorus- and titanium-alloyed austenitic stainless steels under electron irradiation at room temperature

2020 ◽  
pp. 27-34
Author(s):  
D. A. Perminov ◽  
Keyword(s):  
Positron Annihilation ◽  
Electron Irradiation ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Positron Annihilation Spectroscopy ◽  
High Concentration ◽  
Noticeable Effect ◽  
Vacancy Defects ◽  
Positron Annihilation Study

The effect of phosphorus and titanium additions on the accumulation of vacancy defects in Cr16Ni15Mo3 austenitic stainless steels under electron irradiation at room temperature is studied by positron annihilation spectroscopy. It is shown that, at this temperature, phosphorus has no noticeable effect on the accumulation of vacancy defects. This is due to the low mobility of vacancies and the low concentration of impurities. Titanium, due to its high concentration, enhances the accumulation of vacancy defects during irradiation, but this effect is weak.

Electron irradiation induced microstructural modifications in BaCl2 doped PVA: A positron annihilation study

2008 ◽  
Vol 93 (8) ◽  
pp. 1554-1563 ◽  
Author(s):  
A. Harisha ◽  
V. Ravindrachary ◽  
R.F. Bhajantri ◽  
Ismayil ◽  
Ganesh Sanjeev ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Electron Irradiation ◽  
Positron Annihilation Study

Electron Irradiation Induced Vacancy Defects Detected by Positron Annihilation in 6H-SiC

2005 ◽  
Vol 483-485 ◽  
pp. 473-476 ◽  
Author(s):  
Marie France Barthe ◽  
L. Henry ◽  
S. Arpiainen ◽  
G. Blondiaux
Keyword(s):  
Temperature Dependence ◽  
Positron Annihilation ◽  
Electron Energy ◽  
Electron Irradiation ◽  
Positron Lifetime ◽  
Resolution Function ◽  
Vacancy Defects ◽  
Nitrogen Doped

This paper presents positron lifetime results which give information on the nature of vacancy defects induced by electron irradiation in bulk nitrogen doped (nD-nA= 2.3x1017 cm-3) Cree 6H-SiC. The electron irradiations have been performed at different energies and with different fluences from 5􀂗1017 e-cm-2 to 3􀂗1018 e-cm-2. Positron lifetime have been measured with a 22NaCl source as a function of temperature between 15 and 300 K. The lifetime spectra were analyzed as sums of two exponential lifetime components 􀁗i weighted by the intensities Ii, convoluted with the resolution function. From the temperature dependence of the lifetime spectra we can infer that several vacancy defects exist in the electron irradiated n-type 6H-SiC. The nature of detected vacancy defects depends on the electron energy.

Positron Lifetime Studies of Polyaniline Conducting Polymers

1995 ◽  
Vol 413 ◽  
Author(s):  
C. M. Huang ◽  
J. Liu ◽  
T. C. Sandreczki ◽  
Y. C. Jean
Keyword(s):  
Positron Annihilation ◽  
Room Temperature ◽  
Positron Lifetime ◽  
The Other ◽  
Chemical Compositions ◽  
Lifetime Measurements ◽  
Positron Annihilation Lifetime ◽  
Positron Lifetimes ◽  
Lifetime Studies ◽  
Made In

ABSTRACTPositron annihilation lifetime measurements are made in a series of polyaniline polymers with different chemical compositions and protonation ratios at room temperature. Two positron lifetimes are observed in these materials: one is assigned to annihilation in the bulk and the other to voids created due to protonation. A relationship between conductivities and positron annihilation probabilities is found.

Annealing Process of Defects in Epitaxial SiC Induced by He and Electron Irradiation: Positron Annihilation Study

2001 ◽  
Vol 353-356 ◽  
pp. 537-542 ◽  
Author(s):  
Atsuo Kawasuso ◽  
F. Redmann ◽  
Reinhard Krause-Rehberg ◽  
Peter Sperr ◽  
Thomas Frank ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Electron Irradiation ◽  
Annealing Process ◽  
Positron Annihilation Study

Defects in Electron Irradiation Te-Doped GaSb Studied by Positron Lifetime Spectroscopy

2008 ◽  
Vol 607 ◽  
pp. 140-142
Author(s):  
H. Li ◽  
J.Y. Ke ◽  
J.B. Pang ◽  
Bo Wang ◽  
Z. Wang
Keyword(s):  
Electron Irradiation ◽  
Irradiation Dose ◽  
Room Temperature ◽  
Positron Lifetime ◽  
Rydberg States ◽  
Average Lifetime ◽  
Shallow Trap ◽  
Lifetime Measurements ◽  
Positron Lifetime Spectroscopy ◽  
Antisite Defects

Defects induced by electron irradiation in Te-doped liquid-encapsulated Czochralski–grown GaSb were studied by the positron lifetime spectroscopy. The lifetime measurements under room temperature indicated there were VGa-related defects with a characteristic lifetime of 298 ps in the heavily Te-doped as-grown GaSb samples. The average lifetime increased with the increase of irradiation dose in lightly Te-doped GaSb,but the behavior was opposite in the heavily Te-doped samples. It should be due to the shift of Fermi level in heavily Te-doped GaSb and the occurrence of gallium vacancies in different charge states. In the temperature dependence measurements carried out on heavily Te-doped samples, we observed positron shallow trap, and this shallow trap should be attributed to positrons forming hyrogenlike Rydberg states with GaSb antisite defects.

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