Positron annihilation gamma ray lineshapes in metals

Jackman, T. E.; Schulte, C.W.; Campbell, John L.; Lichtenberger, P. C.; MacKenzie, I. K.; Wormald, Mark R.

doi:10.1088/0305-4608/4/1/001

Cited by 23 publications

(7 citation statements)

References 6 publications

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“…The irradiated region in the center of the samples has been investigated with laterally resolved Doppler broadening (DB) measurements in order to image the ion beam spot. Although the trapping rate of positrons in Mg is rather small and the trapping sites are shallow, 5,19,20 the ion beam spot on the samples has been clearly reproduced within the spatial resolution of the CDBS-facility. As expected from simulations with the program SRIM, which was used to calculate the ion and vacancy distribution, the Doppler broadening of the annihilation line depends significantly on the positron penetration depth, which was adjusted up to 5.5 µm.…”

Section: Discussionmentioning

confidence: 87%

“…Also the diameter of the irradiated area matches the size of the ion beam of 5 mm within the spatial resolution of the CDB-spectrometer. Although the trapping rate of positrons in Mg is rather small and the trapping sites are shallow, 5,19,20 the ion beam spot on the samples has been clearly reproduced.…”

Section: B Laterally Resolved Db-measurements -S(xy)mentioning

confidence: 90%

“…Positron spectroscopy is a well-established tool to investigate lattice defects in solids. 1,2,3,4 It has been widely used to investigate defects in metals 5 and precipitation processes in alloys like for example in the alloy Mg-Ca. 6 Coincident Doppler Broadening Spectroscopy (CDBS) with positrons gains more and more interest since it has proved to be a very sensitive technique to distinguish between different elements in the vicinity of crystal defects.…”

Section: Introductionmentioning

confidence: 99%

“…However, Mg and its alloys are challenging materials for defect spectroscopy with positrons since it has been shown, that in Mg the trapping rate is relatively low 19,20 and the trapping sites are shallow. 5 Whereas the defect induced variation of the Doppler broadening of the positron annihilation line, which is determined by the so called S-parameter, usually lies in the range of 4 − 5 % in metals such as Cu or Al, thermally induced defects in Mg only cause 0.6 %. 21 A standard technique to create defects in metals is the implantation of ions.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and a Mg-Al-Zn alloy with coincident Doppler broadening spectroscopy

et al. 2007

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Crystal defects in magnesium and magnesium based alloys like AZ31 are of major importance for the understanding of their macroscopic properties. We have investigated defects and their chemical surrounding in Mg and AZ31 on an atomic scale with Doppler broadening spectroscopy of the positron annihilation radiation. In these Doppler spectra the chemical information and the defect contribution have to be thoroughly separated. For this reason samples of annealed Mg were irradiated with Mg-ions in order to create exclusively defects. In addition Al-and Zn-ion irradiation on Mg-samples was performed in order to create samples with defects and impurity atoms. The ion irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy (DBS) and compared with preceding SRIM-simulations of the vacancy distribution, which are in excellent agreement. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with coincident Doppler broadening spectroscopy (CDBS) by comparing Mg-ion irradiated AZ31 with Mg-ion irradiated Mg. No formation of solute-vacancy complexes was found due to the ion irradiation, despite the high defect mobility.

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Section: Discussionmentioning

confidence: 87%

Section: B Laterally Resolved Db-measurements -S(xy)mentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and a Mg-Al-Zn alloy with coincident Doppler broadening spectroscopy

et al. 2007

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“…Since positrons are not very efficiently trapped in magnesium due to the shallow trapping sites [12][13][14], the respective investigations were demanding. Therefore, the CDBS is currently equipped with a 4 K cryostat in order to cool the sample and hence increasing the trapping rate.…”

Section: Introductionmentioning

confidence: 99%

New design of the CDB-spectrometer at NEPOMUC for T-dependent defect spectroscopy in Mg

Stadlbauer¹,

Hugenschmidt²,

Schreckenbach³

2008

Applied Surface Science

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A study of the effect of deformation on the shape of the angular correlation of positron annihilation radiation

Brümmer¹,

Dlubek²

1977

Cryst Res and Technol

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Dedicated to M. HIEKE on his 70th birthdayThe influence of plast.ic deformat,ion on the shape of the angular correlation of positron annihilation radiation has been studied for A1 and Ag. The experimental curves were fitted t'o the sum of a parabola and a Gaussian under inclusion of t.he effective resolution function of the apparatus. The obt,ained result's show that not only the intensity but also the width of the parabolic arid Gaussian components are changed. Estima,tions in the manner proposed by HAUTOJARVI yield experiment,al values for the kinetic, potential and binding energy of positrons localized at dislocations.Der EinfluIj der plastischen Verformung auf die Form der Winkelkorrelation der Positronenannihilationsstrahlung wurde fur A1 wid Ag studiert. Die gemessenen Kurven wurden mit der Summe einer Pa,rabel und einer GauBkurve unter Berucksichtiguiig der effektiven Anflosungsfunktion der Apparatur arigepaIjt. Die erhaltenen Ergebnisse zeigen, daIj sich nicht nur die Intensitiit sondern auch die Breite der parabolischen und gaul3formigen Komponente iindert. Abschiitzungen, wie sie von HAUTOJARVI vorgeschlagen wurden, liefern experiment'elle Werte fur die kinetische, potentielle nnd Bindungsenergic der an Versetzungen lokalisierten Positronen.

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Positron annihilation gamma ray lineshapes in metals

Cited by 23 publications

References 6 publications

Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and a Mg-Al-Zn alloy with coincident Doppler broadening spectroscopy

Investigation of the chemical vicinity of crystal defects in ion-irradiated Mg and a Mg-Al-Zn alloy with coincident Doppler broadening spectroscopy

New design of the CDB-spectrometer at NEPOMUC for T-dependent defect spectroscopy in Mg

A study of the effect of deformation on the shape of the angular correlation of positron annihilation radiation

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