Fermi Surface of Nanocrystalline Embedded Particles in Materials: bcc Cu in Fe

Nagai, Yasuyoshi; Chiba, Toshinobu; Tang, Zheng; Akahane, Takashi; Kanai, Tsuneyuki; Hasegawa, Masayuki; Takenaka, Mitsuru; Kuramoto, Eiichi

doi:10.1103/physrevlett.87.176402

Cited by 48 publications

(42 citation statements)

References 15 publications

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“…Very recently, Nagai et al have investigated successfully the Fermi surface of coherently embedded Cu nanoclusters having the unusual bcc crystal structure. 53 Here the concept of position confinement in embedded nanoclusters was used in combination with the 2D-ACAR technique.…”

Section: Discussionmentioning

confidence: 99%

Positron confinement in embedded lithium nanoclusters

et al. 2002

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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.

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Section: Discussionmentioning

confidence: 99%

Positron confinement in embedded lithium nanoclusters

et al. 2002

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“…2D-ACAR allows a detailed investigation of the electronic structure of a material. 32,8,6 Experimental details of the setup can be found in Refs. 5 and 6, where positron confinement in Li nanoclusters in MgO is investigated.…”

Section: Positron Beam Analysismentioning

confidence: 99%

Formation of solid Kr nanoclusters in MgO

et al. 2003

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The phenomenon of positron confinement enables us to investigate the electronic structure of nanoclusters embedded in host matrices. Solid Kr nanoclusters are a very interesting subject of investigation because of the very low predicted value of the positron affinity of bulk Kr. In this work, positron trapping in solid Kr nanoclusters embedded in MgO is investigated. The Kr nanoclusters were created by means of 280 keV Kr ion implantation in single crystals of MgO͑100͒ and subsequent thermal annealing at a temperature of 1100 K. The nanoclusters were observed by cross-sectional transmission electron microscopy in high-resolution mode. The fcc Kr nanoclusters are rectangularly shaped with sizes of 2 to 5 nm and are in a cube-on-cube orientation relationship with the MgO host matrix. From the Moiré fringes in high-resolution recordings, the lattice parameter of the solid Kr was deduced and found to vary from 5.3 to 5.8 Å. The corresponding pressures are 0.6 -2.5 GPa as found using the Ronchi equation of state. The relationship between lattice parameter and cluster size was investigated and it was found that the lattice parameter increases linearly with increasing nanocluster size. The defect evolution during annealing was monitored by means optical absorption spectroscopy and positron beam analysis. No evidence of positron trapping was found despite the very low positron affinity of solid Kr. Alternative definitions of the positron affinity are proposed for application to insulator materials.

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“…The precipitation of copper from supersaturated Fe-Cu alloys has been investigated extensively, both experimentally [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and theoretically. [21][22][23][24] It is now generally accepted that, in the initial stage, fully coherent Cu precipitates inherit the bcc structure of the ␣-Fe matrix.…”

Section: Introductionmentioning

confidence: 99%

In situdetermination of aging precipitation in deformed Fe-Cu and Fe-Cu-B-N alloys by time-resolved small-angle neutron scattering

Dijk

Paladugu

et al. 2010

Phys. Rev. B

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We performed in situ time-resolved small-angle neutron scattering ͑SANS͒ measurements on high-purity Fe-Cu and Fe-Cu-B-N alloys during isothermal aging at 550°C in order to study the potential self-healing of deformation-induced defects by nanosized Cu precipitation. Three different samples with 0%, 8%, and 24% prestrain were used to study the influence of variable defect levels on the Cu precipitation kinetics. The time-resolved SANS measurements show the presence of two contributions corresponding to spherical precipitates and precipitation at dislocations and/or interfaces, as confirmed by complementary transmission electron microscopy experiments. For the Fe-Cu alloy, prestrain was found to accelerate the formation of spherical precipitates in initial aging stage and lead to a significant enhancement of copper precipitation at dislocations and/or interfaces. For the Fe-Cu-B-N alloy, the addition of boron and nitrogen accelerates the formation of spherical precipitates but suppresses the precipitation along dislocations in the prestrained samples.

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Fermi Surface of Nanocrystalline Embedded Particles in Materials: bcc Cu in Fe

Cited by 48 publications

References 15 publications

Positron confinement in embedded lithium nanoclusters

Positron confinement in embedded lithium nanoclusters

Formation of solid Kr nanoclusters in MgO

In situdetermination of aging precipitation in deformed Fe-Cu and Fe-Cu-B-N alloys by time-resolved small-angle neutron scattering

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