The effect of vacancy formation on the temperature dependence of the positron lifetime

Bergersen, B.; Stott, M. J.

doi:10.1016/0038-1098(69)90177-x

Cited by 269 publications

(61 citation statements)

References 3 publications

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“…By using the trapping model, [23][24][25] the concentration of vacancies can be estimated. When positrons are trapped by vacancies or dislocations in a specimen, the following relation is obtained:…”

Section: Discussionmentioning

confidence: 99%

Recovery of Hydrogen Induced Defects and Thermal Desorption of Residual Hydrogen in LaNi<SUB>5</SUB>

2002

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Lattice defects induced by initial hydriding and their effect on residual hydrogen content in LaNi 5 have been studied by means of positron lifetime spectroscopy and hydrogen thermal desorption measurement. Component analyses of positron lifetime spectra show that surprising amount of vacancies together with dislocations are generated by the initial hydriding. Vacancy migration in LaNi 5 after hydrogen desorption at room temperature is observed around 423-673 K, while dislocations in LaNi 5 are much more stable. Hydrogen thermal desorption measurement shows that the release of residual hydrogen occurs mainly in the temperature range from 450 to 650 K, and it ceases at about 800 K. The release temperature of residual hydrogen closely corresponds with the temperature of vacancy migration and annihilation in LaNi 5 . Residual hydrogen in LaNi 5 is most likely trapped by vacancies and vacancy clusters, which are induced by hydriding.

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Section: Discussionmentioning

confidence: 99%

Recovery of Hydrogen Induced Defects and Thermal Desorption of Residual Hydrogen in LaNi<SUB>5</SUB>

2002

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“…A difference of the electrons concentration in the perfect lattice and defects induces the differences in the measured annihilation characteristics. The standard trapping model takes into account only annihilation and trapping rates at different defects [1][2][3]. For one type of defect, e.g.…”

Section: Standard Trapping Modelmentioning

confidence: 99%

“…Thus, the annihilation characteristics reflect the local properties of the sample but they are averaged over the volume. This is not taken into account in the simple positron trapping model proposed by Brandt [1], Bergersen and Stott [2], and Connors and West [3], which is commonly used in the analysis of the PALS or DB spectra. In this model it is assumed that the defects which trap positrons with a certain rate are distributed homogeneously.…”

Section: Introductionmentioning

confidence: 99%

Positron annihilation studies of recrystallization in the subsurface zone induced by friction in magnesium—effect of the inhomogeneity on measured positron annihilation characteristics

Dryzek

2013

Appl. Phys. A

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The discussion of the positron annihilation studies of crystal structure defects, like vacancies, dislocations, grain boundaries and the defect depth profile, is presented. The role of the positron implantation depth and positron diffusion in such studies has been considered in detail. For description of the measured annihilation characteristics the proposed theoretical models take into account both effects. The annealing studies of defects created in pure magnesium by compression or dry sliding-wear were used for demonstration of the discussed thesis. The positron lifetime measurements were applied for monitoring open volume defects behavior. It was demonstrated that annealing at the temperature of about 300°C removes the defects created by compression. Application of the proposed model to description of the data obtained allows to determine the activation energy of the grain boundary mobility in pure magnesium equal to Q = 0.56 ± 0.18 eV. However, defects created by the dry sliding are not completely annealed up to the temperature of 500°C. The defect depth profile induced by dry sliding evolves with the annealing temperature in such a way that at the worn surface concentration of defects gradually decreases but at the depth between 60 and 100 µm the generation of new defects takes place at temperature of 150 and 225°C. Above 300°C the defects still are extended up to the depth of about 80 µm.

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“…18,19) This lifetime component comes from free positrons in the matrix. By using the trapping model, [20][21][22] the dislocation density can be estimated. When positrons are trapped by dislocations in a specimen, the following relation is given:…”

Section: Recovery Process Of Hydrogen-induced Lattice Defects On Isocmentioning

confidence: 99%

Hydrogen-Induced Vacancy Generation Phenomenon in Pure Pd

et al. 2002

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Lattice defects induced by hydriding in pure Pd have been studied by means of positron lifetime spectroscopy. Component analyses of positron lifetime spectra show that a surprising amount of vacancies together with dislocations are generated by the hydriding at room temperature. Vacancy migration in pure Pd after hydriding is observed around 378 K. Dislocations are much more stable and its migration is observed around 873 K. During the vacancy recovery process, secondary defects, that is, dislocation loops are formed.

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The effect of vacancy formation on the temperature dependence of the positron lifetime

Cited by 269 publications

References 3 publications

Recovery of Hydrogen Induced Defects and Thermal Desorption of Residual Hydrogen in LaNi<SUB>5</SUB>

Recovery of Hydrogen Induced Defects and Thermal Desorption of Residual Hydrogen in LaNi<SUB>5</SUB>

Positron annihilation studies of recrystallization in the subsurface zone induced by friction in magnesium—effect of the inhomogeneity on measured positron annihilation characteristics

Hydrogen-Induced Vacancy Generation Phenomenon in Pure Pd

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