摘要:

We discuss a charge-density-wave instability for electrons in quasi-one-dimensional structures due to Coulomb interaction effects. The two plasmon modes (ω+, ω−) of a double-quantum-wire structure are studied. The effect of a finite local-field correction is discussed. For small wavenumbers, it is shown that for a fixed wire distance and wire radius the energy of the ω−plasmon vanishes if the particle density is smaller than a critical value. The disappearance of the ω−mode corresponds to a singularity in the static susceptibility of the system.

ISSN:0950-0839    

DOI:10.1080/09500839208219028

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We present Monte Carlo results for theT=0K recombination of an electron hopping on a spatially and energetically disordered lattice under the influence of the Coulomb interaction of a stationary hole as a function of the width Σ of the energy distribution and of the localization radius Γ. Those simulations indicate that, when Σ is small, the dynamics is anisotropic towards the hole and when Σ is large, isotropy is recovered, and that, when Γ is large, recombination is diffusion limited and when Γ is small, the lifetime is limited by the final transition. The diffusion−limited regime is further analysed as a function of the excitation density. Simulations show that, for densities below 1017cm−3, recombination is geminate and the lifetime distribution peaks at 10−4s; above that density, it is non-geminate and the lifetime distribution shifts to 10−6s.

ISSN:0950-0839    

DOI:10.1080/09500839208219029

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The n-type character of nominally undoped hydrogenated amorphous Ge (a-Ge: H) films is clearly demonstrated by the effect of the addition of trimethylborane (CH3)3B to the gas atmosphere of the sputtering preparation process. The minimum conductivity of the fully compensated material was investigated as a function of the H content and used to determine the mobility gap. The mobility gap obtained for sputtered boron−and−carbon−doped a-Ge : H films, which is always smaller than the optical gap (ETorE04), increases with increasing H content and saturates at 0·95 eV, whereas for glow−discharge films a value of 1·03 eV was found.

ISSN:0950-0839    

DOI:10.1080/09500839208219030

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

High-resolution electron microscopy has been used to investigate the structure of coherent twin boundaries in ordered Cu3Au. Apart from confirming the previously established symmetric structure S and asymmetric structure A, the composition of atomic columns in the boundary has been examined. Evidence is presented for a new asymmetric structure which differs from structure A in the arrangement of Au and Cu atoms in the atomic columns at the boundary.

ISSN:0950-0839    

DOI:10.1080/09500839208219031

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Recent results of a two-dimensional finite−element modelling of the elastic distortions resulting from the lattice mismatch between γ− and γ−phases have been used to estimate the relative contribution of internal stresses to the broadening of γ-ray diffraction peaks, which has been observed at high temperatures in the case of some nickel-based superalloy single crystals. In the case of CMSX-2 alloy, it is found that the magnitude of the broadening of {220} and {200} peaks calculated when taking the elastic distortions into account is in good agreement with the experimental observations.

ISSN:0950-0839    

DOI:10.1080/09500839208219032

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Not only the directions, but also the senses and magnitudes of the Burgers vectors b of dislocations in Al70Co15Ni15decagonal quasicrystal have been determined for the first time by the large-angle convergent-beam electron diffraction technique. Right−hand screw dislocations with b = [3/400000] and [100000] have been determined.

ISSN:0950-0839    

DOI:10.1080/09500839208219033

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A stable one-dimensional quasicrystal has been found in slowly cooled Al75Pd15Fe10. The one-dimensional quasicrystal can be derived from a two-dimensional decagonal quasicrystal by introducing a finite linear phason strain. The melting temperature of the one-dimensional quasicrystal was measured to be lower than that of the two-dimensional decagonal quasicrystal.

ISSN:0950-0839    

DOI:10.1080/09500839208219034

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The transformation of the decagonal quasicrystalline phase in Al62Cu20Co15Si3and Al65Cu15Co20to a normal crystalline phase was studied by electron diffraction and high-resolution electron microscopy. The transformation was induced by electron irradiation at room temperature. In the first stage the decagonal phase transformed into a b.c.c. phase. After prolonged irradiation this phase ordered to a CsCl-type cubic phase.

ISSN:0950-0839    

DOI:10.1080/09500839208219035

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0950-0839    

DOI:10.1080/09500839208219036

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor