摘要:

Antiphase-domain-boundary (APB) tubes have been observed in a Ni3Ga single crystal deformed at 200°C. Two families of dislocations have been observed in a (010) sample and they have been identified to belong to the primary and secondary octahedral (110){111} slip systems. APB tubes have been observed in both of the two dislocation system. In spite of double slip, many APB tubes have been found to end at dislocation dipoles, a feature which is consistent with the cross-slip and annihilation model of Chou and Hirsch.

ISSN:0950-0839    

DOI:10.1080/09500839308240951

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The interfaces between Bi2Sr2CaCu2Oxthin films and SrTiO3substrates have been investigated by high-resolution electron microscopy. A BiO monolayer, BiO adjacent layers and a SrO layer respectively, have been identified to be the first grown layers of the films. Interfacial defects, such as misfit dislocations and planar stacking faults, have been observed in the films in the vicinity of the interface.

ISSN:0950-0839    

DOI:10.1080/09500839308240952

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In the Al-Pd-Mg system, a Mackay icosahedron (MI) type of icosahedral phase (I-phase) with the F-type superlattice order and a decagonal phase (D-phase) have been found to form in a melt-quenched state, in addition to the Frank-Kasper (FK) type of stable I-phase reported previously. This is the first example in which the three types of quasicrystalline phase are formed in the same alloy system. The formation range of the FK-type I-phase in the melt-quenched state is rather wide; 5–20 at.%Pd and 20–45 at.%Mg. In contrast, the MI-type I-phase and D-phase are formed in small composition ranges around Al52Pd31Mg17and Al74Pd21Mg5respectively. Electron diffraction studies have shown that the period along the tenfold axis of the D-phase is about 1.6 nm. The formation and stability of the MI-type and FK-type I-phases have been discussed in terms of a Hume-Rothery rule.

ISSN:0950-0839    

DOI:10.1080/09500839308240953

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Ion implantation of pure aluminium with thallium induces the formation of nanosized crystalline inclusions of thallium with a f.c.c. structure. The size of the inclusions depends on the implantation conditions and subsequent annealing treatments, and is typically in the range from 1 to 10 nm. The inclusions are aligned topotactically with the aluminium matrix with a cube-cube orientation relationship, and they have a truncated octahedral shape bounded by {111} and (001) planes. The lattice parameter of the f.c.c. thallium inclusions is 0.484±0.002 nm, which is slightly but significantly larger than in the high-pressure f.c.c. thallium phase known to be stable above 3.8 GPa.

ISSN:0950-0839    

DOI:10.1080/09500839308240954

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The electrical resistivity of ordered and disordered Cu-15 at.% Pd alloys is measured and the resistivity changes during continuous heating are compared with results obtained by differential thermal analysis. The electrical resistivity of both samples increases anomalously near to the order-disorder transition temperatureTc, being higher than that atTcand then dramatically decreases just belowTc, exhibiting a sharp peak on the electrical resistivity curve. Also, on the electrical resistivity curve of the disordered sample, a further peak is formed at a lower temperature than the peak formed just belowTc. Differential thermal analysis reveals that the resistivity changes involving the anomalous increase correspond generally to the exothermic and endothermic peaks for ordering and disordering of the samples during continuous heating. Combining such information with antiphase domains (APDs) structure and selected-area diffraction spot intensities observed by transmission electron microscopy, it is confirmed that the anomalous increase in the resistivity observed in Cu-15 at.% Pd alloys is related to development of long-range order, independent of APD size.

ISSN:0950-0839    

DOI:10.1080/09500839308240955

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Investigations of secondary-electron (SE) emission from magnesium oxide smoke cubes have been made in coincidence with different primary-electron beam losses and geometrical configurations. For aloof-beam situations at distances of up to 10 nm outside the cube, SEs are observed in coincidence with surface excitations of the valence electrons. For beams which penetrate the cube, additional SEs arise following either atomic core excitation or, with somewhat lower probability, bulk valence excitation.

ISSN:0950-0839    

DOI:10.1080/09500839308240956

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

X-ray photoemission measurements of NaCuO2samples and reference materials have been made to study the electronic structure of the copper ions and the Cu-O interaction in these materials. Cu 2p3/2spectra of Cu2O, CuO and NaCuO2compounds are compared. The results are discussed in terms of three formal oxidation states of copper. The chemical shifts of the Cu 2p lines are in good agreement with recent theoretical values.

ISSN:0950-0839    

DOI:10.1080/09500839308240957

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The creation of metastable defects in hydrogenated amorphous silicon subjected to laser pulses with laser pulse energy density in the rangeU= (2.5–33) 10−3J cm−2has been investigated. After a rise time nearly independent ofU, saturation of the defect densityNsatis observed, andNsatvaries linearly withUin the range of energies considered. A model including the light-induced annealing of defects fits the present experimental data.

ISSN:0950-0839    

DOI:10.1080/09500839308240958

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A positron beam has been applied to diamond-like carbon films prepared by the nitrogen-ion bombardment of polyphenyl ether. A diffusion model applied to measurements taken at various energies clearly indicates the film thickness. Positron annihilation spectroscopy should therefore prove an invaluable method in the non-destructive assessment of these layers.

ISSN:0950-0839    

DOI:10.1080/09500839308240959

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The temperature dependences of the electron drift mobility μdin hydrogenated amorphous silicon (a-Si:H) and in a set of four hydrogenated amorphous Si1−xCx(a-Si1−xCx:H) alloys withx ≤0.1 has been determined from steady-state photoconductivity and response time measurements. The temperature dependence of the μdcurve of a-Si: H shows a region with a single activation energy of 0.13 eV between 150 and 300 K, and an electron drift mobility of about 1 cm2V−1s−1at 300 K. For the alloys, the single-activation-energy region is steeper and moves to higher temperatures. The results confirm that the conduction-band tail widens rapidly with increasingxin a-Si1−xCx:H.

ISSN:0950-0839    

DOI:10.1080/09500839308240960

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor