摘要:

Transmission electron microscopy analyses of hot-pressed α-Sic deformed at 1600°C have shown the activation of the basal plane with glide dislocations dissociated into Shockley partials. Loop nucleations have been frequently observed along the dislocation lines and a climb mechanism is proposed to explain, the experimental analyses.

ISSN:0950-0839    

DOI:10.1080/09500838908206433

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The dissociation of [101] screw dislocations in Ni3Al has been examined using high-resolution electron microscopy. [101] superdislocations are found to be dissociated into (a/2)[101] superpartial dislocations on the (010) cube cross-slip plane. These superpartials in turn dissociate into complex stacking faults on the (111) or (111) which are bounded by Shockley partials in agreement with theoretical predictions. The degree of antiphase boundary spreading on (010) was found to increase with deformation temperature while the superpartial core dissociations remain unchanged.

ISSN:0950-0839    

DOI:10.1080/09500838908206434

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Direct structural images of a twin boundary in a superconducting Y–Ba–Cu–O ceramic have been obtained at 0·19 nm resolution by high-resolution transmission electron microscopy and an image processing technique. It was found that theaandbplanes of a twin domain gradually change to thebandaplanes of a neighbouring twin domain across a twin boundary. This involves a shifting of the respective planes by a distance (⅓∼½)d(110)along the boundary as well as the rotation of the planes by ø ≃ 2(b−a)/(a + b) across the boundary. Also, this transition takes place within approximately four times the (110) interplanar spacingd(100), which is considered as the twin boundary layer thickness.

ISSN:0950-0839    

DOI:10.1080/09500838908206435

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The neutron reflectivity from a sample consisting of a silicon nitride layer on a crystalline silicon substrate has been measured. The structure of the sample normal to the reflecting surface has been modelled to produce a scattering length density profile whose simulated reflectivity closely matches that experimentally determined. The layer thickness and the corresponding interface structures are detailed. Two modelling techniques have been used, one based on the well known Born and Wolf matrices and the other based on the Abeles method. The two techniques are compared and the sensitivity of the two techniques are discussed.

ISSN:0950-0839    

DOI:10.1080/09500838908206436

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

After an initial anneal at 180°C, n-type a-Si: H specimens have been subjected to different combinations of illumination and quench treatments so as to produce identical Fermi-level positions after preparation. Contrary to expectations, we find that the differently prepared metastable states relax with significantly different rates, with activation energies ranging from almost zero to 1·8 eV. The relevance of these results is discussed in terms of existing models of the autocompensation process.

ISSN:0950-0839    

DOI:10.1080/09500838908206437

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The results of the scaling theory of localization are briefly summarized. Special emphasis is placed on features which are of importance for electrical transport in amorphous semiconductors. The critical behaviour of the average d.c. conductivity near the mobility edge is used to explain the activated behaviour of the temperature-dependent conductivity. If the system is universal near the mobility edge, the prefactor of the activated conductivity is a number, which is given by the critical conductance divided by a characteristic length that may be interpreted as a mean phase breaking distance. The new and most important result is that the statistical properties of the conductance have to be taken into account when calculating the prefactor to obtain a quantitatively reasonable description. Thus mesoscopic fluctuations seem to have much wider consequences than assumed hitherto.

ISSN:0950-0839    

DOI:10.1080/09500838908206438

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0950-0839    

DOI:10.1080/09500838908206439

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor