Angular Distribution of Annihilation Radiation from Plastically Deformed Aluminum

Berko, S.; Erskine, J.C.

doi:10.1103/physrevlett.19.307

Cited by 94 publications

(21 citation statements)

References 6 publications

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“…This effect is well known since the early studies of positron trapping at defects in metals, 7 but is clearly visible also in semiconductors. [8][9][10][11] The sensitivity of the effect to the size of the positron trap can be judged from Fig.…”

Section: Theorymentioning

confidence: 78%

“…7,14 Since smearing enhances the counting rate beyond the Fermi cutoff ͑see inset in Fig. 4͒, additional counts fall in a region where the counting rate in the bulk metal reference spectrum is low, thus producing a peak in the ratio curves currently used for presenting CDB data.…”

Section: Theorymentioning

confidence: 99%

“…Pioneer ACAR work on defected materials is in Ref. 7; more recent results can be found in Refs. [8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Positron localization effects on the Doppler broadening of the annihilation line: Aluminum as a case study

et al. 2005

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The coincidence Doppler broadening ͑CDB͒ technique is widely used to measure one-dimensional momentum distributions of annihilation photons, with the aim of obtaining information on the chemical environment of open-volume defects. However, the quantitative analysis of CDB spectra needs to include also purely geometrical effects. A demonstration is given here, on the basis of CDB spectra measured in quenched and in deformed pure aluminum. The comparison of the experimental results with ab initio computations shows that the observed differences come from the difference in free volume seen by positrons trapped in quenched-in vacancies or in vacancylike defects associated to dislocations. The computation reproduces accurately all details of CDB spectra, including the peak near the Fermi break, which is due to the zero-point motion of the confined positron.

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Section: Theorymentioning

confidence: 78%

Section: Theorymentioning

confidence: 99%

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Positron localization effects on the Doppler broadening of the annihilation line: Aluminum as a case study

et al. 2005

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“…Since positron annihilation spectroscopy is a powerful and sensitive probe for studying the electronic structure and the annealing behavior of defects in solids [1,2]. The positron is in the free Bloch state in a perfect crystal and in a bound state, when trapped by a crystal lattice defect, e.g., a vacancy.…”

mentioning

confidence: 99%

Thermal vacancies and self‐diffusion energy in 2024 Al‐alloy by positron annihilation lifetime technique

Badawi

Abdelrahman

Abdallah

2009

Phys. Status Solidi (c)

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Positron annihilation lifetime technique (PALT) is one of the most important nuclear non‐destructive techniques. It was used to study the thermal vacancies in one of the most important engineering aluminum alloys – the 2024 Al‐alloy. Quenching experiments were usually performed on thin specimens to ensure a uniform quenching rate throughout the specimen. The specimens were prepared with dimensions of 0.15 × 1.5 × 1.5 cm3. After grinding, polishing and etching, samples of 2024 were homogenized for 12 h at 673 K and annealed for 90‐min., before being quenched in water (277 K). Positron lifetime measurements followed. From such measurements, it is possible to deduce the vacancy formation enthalpy, which in combination with the results of self‐diffusion measurements, gives a value for migration enthalpy of the vacancy. These are very important quantities in the study of the annealing of irradiation induced defects. The use of the quenching technique in the positron annihilation study has the advantage that it allows a distinction between vacancy and dislocation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…PAS, as the name suggests, is the spectroscopy of photons emerging from the annihilation of positrons with electrons. The depth-resolved PAS method is based on: (1) the availability of beams[ 1-71 of positrons that can be used to probe various controlled depths (in the range of a few pm )[8] of a material; (2) the propensity of positrons to seek out low-density regions of a solid such as voids and vacancies [9,10]; and (3) the annihilation of positrons and electrons into y-rays that carry information about the low-ion-density regions and escape the test material without significant attenuation [ 11. In bulk materials, the technique can detect vacancy-like defects at a sensitivity level of 5~1 0 '~ ~r n -~. When an energetic positron enters a material, it thermalizes rapidly (within 1-10 psec) and undergoes diffusion (or is trapped at a defect site) until it annihilates with an electron.…”

Section: Positron Annihilation Spectroscopymentioning

confidence: 99%

Studies of defects in the near-surface region and at interfaces using low energy positron beams

Asoka‐Kumar

1997

Bull Mater Sci

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Positron Annihilation Spectroscopy (PAS) is a powerful probe to study open-volume defects in solids. Its su'ccess is due to the propensity of positrons to seek out low-density regions of a solid, such as vacancies and voids, and the emissions of gamma rays from their annihilations that carry information about the local electronic environment. The development of low-energy positron beams allows probing of defects to depths of few microns, and can successfully characterize defects in the near-surface and interface regions of several technologically important systems. This review focuses on recent studies conducted on semiconductor-based systems. IntroductionThe last three decades saw an explosive growth in methods to produce materials with unique properties. Many of these techniques allowed the engineering of high-quality layered structures (both homo-and hetero-structures). Along with these advances, the need to characterize the defect content of these structures became evident. With many advanced materials, a single characterization method often is inadequate. Therefore, the material-research community has relied on a variety of techniques to control and optimize their processing steps. In this context, Positron Annihilation Spectroscopy (PAS) has become a powerful, nondestructive probe to characterize dilute quantities of open-volume defects.With the development of intense, variable-energy positron beams, it is possible now to examine defects in the near-surface regions and buried interfaces. Below, we describe the application of PAS to several advanced semiconductor-based systems, and include the following topics: defects in MBE-grown Si and GaAs, hydrogen interaction with Si dangling bonds, and electromigration-induced vacancy formation.

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Angular Distribution of Annihilation Radiation from Plastically Deformed Aluminum

Cited by 94 publications

References 6 publications

Positron localization effects on the Doppler broadening of the annihilation line: Aluminum as a case study

Positron localization effects on the Doppler broadening of the annihilation line: Aluminum as a case study

Thermal vacancies and self‐diffusion energy in 2024 Al‐alloy by positron annihilation lifetime technique

Studies of defects in the near-surface region and at interfaces using low energy positron beams

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