Positron confinement in ultrafine embedded particles: Quantum-dot-like state in an Fe-Cu alloy

Nagai, Yasuyoshi; Hasegawa, M.; Tang, Zheng; Hempel, A.; Yubuta, Kunio; Shimamura, T.; Kawazoe, Yoshiyuki; Kawai, Akio; Kano, Fumihisa

doi:10.1103/physrevb.61.6574

Cited by 198 publications

(95 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The fcc phase for bulk Li is otherwise only observed at low temperatures and high pressures. 18,19 A similar effect was reported in the work mentioned above 12 where the crystal structure of Cu nanoclusters embedded in Fe is expected, on the basis of lattice parameter similarity, to be bcc rather than fcc.…”

Section: Introductionsupporting

confidence: 60%

“…Previously, positron confinement in Cu nanoclusters embedded in Fe was investigated. 12 By analysis of the S and W parameters of the Doppler broadening curves these authors found that, after thermal aging, approximately 90% of all positrons annihilate in the Cu nanoclusters while Cu makes up only 1.0 wt % of the Fe:Cu composite material.…”

Section: Introductionmentioning

confidence: 99%

“…Positrons are known as sensitive self-seeking probes of defects in materials and can provide detailed information on the electronic structure of defects or bulk materials 8,9 such as the morphology of Fermi surfaces. 10,11 The concept of positron confinement was introduced by Nagai et al 12 Under certain conditions, nanoclusters act as a potential well to positrons; i.e., the wave function of the positron is spatially confined within the nanocluster in three dimensions. A positron confined in a nanocluster will annihilate there and will thus provide unique information on the electronic and crystal structure of the nanocluster, which can be quite different from the bulk material of the atoms constituting the nanocluster.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Positron confinement in embedded lithium nanoclusters

et al. 2002

View full text Add to dashboard Cite

Quantum confinement of positrons in nanoclusters offers the opportunity to obtain detailed information on the electronic structure of nanoclusters by application of positron annihilation spectroscopy techniques. In this work, positron confinement is investigated in lithium nanoclusters embedded in monocrystalline MgO. These nanoclusters were created by means of ion implantation and subsequent annealing. It was found from the results of Doppler broadening positron beam analysis that approximately 92% of the implanted positrons annihilate in lithium nanoclusters rather than in the embedding MgO, while the local fraction of lithium at the implantation depth is only 1.3 at. %. The results of two-dimensional angular correlation of annihilation radiation confirm the presence of crystalline bulk lithium. The confinement of positrons is ascribed to the difference in positron affinity between lithium and MgO. The nanocluster acts as a potential well for positrons, where the depth of the potential well is equal to the difference in the positron affinities of lithium and MgO. These affinities were calculated using the linear muffin-tin orbital atomic sphere approximation method. This yields a positronic potential step at the MgOʈLi interface of 1.8 eV using the generalized gradient approximation and 2.8 eV using the insulator model.

show abstract

Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Positron confinement in embedded lithium nanoclusters

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Nagai et al have shown the formation of voids and subsequent growth of Cu precipitates in voids in Fe-0.6 mass%Cu. 43) Xu et al detected an initial precipitation of Cu clusters at an early stage of irradiation prior to void formation. 44) The synergetic effect, the concurrent formation of vacancy clusters and precipitates, however, is not fully understood.…”

Section: Migration Of Alloying Elementsmentioning

confidence: 99%

Factors That Influence Cascade-Induced Defect Growth in Pure Metals and Model Alloys

Yoshiie

2005

Mater. Trans.

View full text Add to dashboard Cite

For the development of materials in a fusion reactor environment without a fusion reactor, it is important to understand the generation and accumulation of point defects. This paper discusses five important factors in metals that influence the initial stage of defect clustering under cascade damage conditions. The effect of the PKA energy spectrum on damage evolution was explained from the viewpoint of subcascade formation. Two origins of damage rate dependence of defect cluster formation, direct mutual annihilation of point defects and annihilation of point defects at cascade-induced defect clusters, were mentioned. As the effect of motion of interstitial clusters, an example was given to illustrate the strong correlation between the mobility of interstitial clusters and void growth. Thermal activation processes depend on irradiation temperature. Varying irradiation temperature experiment was evaluated as a technique for investigating the point defect processes during irradiation. Migration of alloying elements during irradiation was reviewed from the standpoint of the interaction of alloying elements with point defects.

show abstract

“…77 Early positron experiments showed that positrons could indeed be confined within nano-, and even subnanosized particles of Cu embedded within a dilute Fe-Cu alloy, and that these ultrafine particles had the momentum distribution very similar to bulk Cu. 78 Subsequent 2D-ACAR experiments on Cu nanocrystals embedded in Fe, prepared by the thermal aging of a single crystal of a Fe-1.0 wt. % Cu alloy, were able to reveal the Fermi surface of bcc Cu with necks reaching out to the {110} Brillouin zone boundaries.…”

Section: Confined Positrons In Precipitatesmentioning

confidence: 99%