Study of vacancy defects in PbSe and Pb1-xSnxSe by positron annihilation

Polity, A.; Krause‐Rehberg, R.; Зломанов, В. П.; Stanov, V.; Chatchaturov, A.; Mäkinen, Seppo

doi:10.1016/0022-0248(93)90423-t

Cited by 17 publications

(11 citation statements)

References 7 publications

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“…Our calculations based on the new GGA scheme reveal a positron lifetime for bulk PbSe of 215 ps, which is in good agreement with the experimental value 220 ps (Ref. [55]). Moreover, positron lifetimes ranging from 340 and 380 ps observed at PbSe nanocrystals demonstrate the existence of positron surface states [91].…”

Section: A Bulk Positron Lifetime and Affinitysupporting

confidence: 89%

Improved generalized gradient approximation for positron states in solids

Kuriplach

Barbiellini

2014

Phys. Rev. B

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Several first-principles calculations of positron-annihilation characteristics in solids have added gradient corrections to the local-density approximation within the theory by Arponen and Pajanne [Ann. Phys. (NY) 121, 343 (1979)] since this theory systematically overestimates the annihilation rates. As a further remedy, we propose to use gradient corrections for other local-density approximation schemes based on perturbed hypernetted chain and on quantum Monte Carlo results. Our calculations for various metals and semiconductors show that the proposed schemes generally improve the positron lifetimes when they are confronted with experiment. We also compare the resulting positron affinities in solids with data from slow-positron measurements.

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Section: A Bulk Positron Lifetime and Affinitysupporting

confidence: 89%

Improved generalized gradient approximation for positron states in solids

Kuriplach

Barbiellini

2014

Phys. Rev. B

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“…Positron lifetime spectroscopy for the PbS powder sample without reaction in the solution yields two components of positron lifetimes τ 1 ∼ 201 ps and τ 2 ∼ 378 ps with the corresponding relative intensities I 1 ∼ 27% and I 2 ∼ 73%, respectively. The positron lifetime for the PbS crystal has been well studied and is found to be 204 ps, which is similar to that obtained here. The positron lifetime τ 1 is thus attributed to annihilation in the defect-free matrix of the PbS crystal in PbS.…”

Section: Resultssupporting

confidence: 85%

“…The positron lifetime τ 1 is thus attributed to annihilation in the defect-free matrix of the PbS crystal in PbS. On the contrary, the positron lifetime τ 2 ∼ 380 ps is higher than that of Pb divacancy found in the Pb 0.93 Sn 0.07 crystal (∼350 ps), which is thus ascribed to a nanovoid with a size of 3 or 4 Pb atoms. In light of the fact that a similar positron lifetime of ∼390 ps has been observed in PbS nanoparticles with the size in the range of 12–16 nm, the nanovoid observed in the present PbS is most probably located at interfaces between the PbS nanoparticles.…”

Section: Resultsmentioning

confidence: 83%

Alternation Mechanism of Lead Sulfate toward Lead Sulfide under Sulfuric Acid Conditions

Sato

Nakata

2020

J. Phys. Chem. C

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Rapid metasomatism of lead sulfide toward lead sulfate under acidic conditions is a geochemical phenomenon that can access the immobilization route of toxic heavy lead; however, the molecular mechanism has not yet been elucidated. Here, we succeeded in studying the alternation mechanism of galena to anglesite under sulfuric acid conditions by an extended mechanistic theory of nucleation, where diffusion and reactions of molecules at mineral interfaces are taken into consideration. There exist large nanovoids with a size of ∼6 Å at the interfaces acting as diffusion pathways of solution molecules with an activation energy of ∼0.1 eV. In addition, protons available in solution readily react with interior surfaces of the above-mentioned nanovoids because of close interaction involving an energy cost of ∼0.2 eV. The diffusive nature and reactive nature of solution molecules at the mineral interfaces govern the anglesite formation, triggering off a low energy cost of ∼0.3 eV under sulfuric acid conditions.

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“…at least two orders of magnitude larger than Pb monovacancy concentrations observed in PbSe single crystals. 33 Indeed, the formation energy of a V Pb V Se divacancy of 1.47 eV was found from our VASP calculation. 25 This implies that even at the highest synthesis temperature, the equilibrium concentration of divacancies is less than 10 -16 per pair of Pb-Se atoms, excluding the divacancy scenario.…”

Section: Resultsmentioning

confidence: 59%

“…The PALS spectra of nearly all thin layers of PbSe NCs were found to display a dominant positron lifetime component 2 with a lifetime of 340 to 380 ps using a three component lifetime analysis. Figure 1 presents the average lifetime 33 The high values for the positron lifetime observed in this study show that annihilation takes place in open spaces that are equal to at least the size of a di-vacancy 33,36 (V Pb V Se ) and act as trapping centers for the positrons stopped inside the PbSe NC. This strongly indicates that the sites at which the positrons annihilate are located predominantly at the surfaces of the PbSe nanocrystals.…”

Section: Resultsmentioning

confidence: 84%

Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

et al. 2013

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Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal

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Study of vacancy defects in PbSe and Pb1-xSnxSe by positron annihilation

Cited by 17 publications

References 7 publications

Improved generalized gradient approximation for positron states in solids

Improved generalized gradient approximation for positron states in solids

Alternation Mechanism of Lead Sulfate toward Lead Sulfide under Sulfuric Acid Conditions

Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

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