摘要:

When spinel is deformed in compression at 400°C along ⟨110⟩, the primary slip plane is found to be {111} with cross-slip occurring on a {001} plane. A comparison of weak-beam images of dislocations from both systems indicates that all dislocations which belong to the primary slip plane are dissociated out of the {111} plane independent of the character of the dislocation. It is proposed that deformation occurs by motion of dislocations in their dissociated state and that the partial dislocations actually glide on parallel glide planes. Movement of these dissociated dislocations is then accompanied by a concurrent migration of the stacking fault which takes place by a local shuffling of the cations. A stacking fault energy for conservative dissociation at 400°C on {001} of 530±90mJ m−2has been determined from weak-beam images of screw dislocations.

ISSN:0950-0839    

DOI:10.1080/09500838808214710

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Convergent-beam electron diffraction has been used to study strain modulation in GaAs/InGaAs superlattices (6% In and 2% In) in plan-view. Reflections from planes inclined to the interface of the superlattice are split with sidebands, the angular separation of which is related to the modulation periodicity. It is inferred from higher-order Laue zone lines that inclined planes on opposite sides of an interface in GaAs and InGaAs layers are rotated towards and away from the interface as a result of distortion due to coherent matching and local relaxation in regions where the GaAs substrate and buffer layer have been ion-milled away.

ISSN:0950-0839    

DOI:10.1080/09500838808214711

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The diffusivity and the migration energy of H in Al at high temperatures have been found to be consistent with low-temperature experiments when the possibility of temporary localization of the H atoms at thermal equilibrium vacancies is taken into account. The migration energy in the perfect lattice is determined to be 0·52±0·07eVand DHo≈ 8 × 10−5m2s−11. These data are in excellent agreement with theoretical and experimental results. From these data the H-vacancy binding energy is determined to be 0·43±0·07eV.

ISSN:0950-0839    

DOI:10.1080/09500838808214712

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

We present a study of the hyperfine structure in the electron spin resonance spectra of phosphorus-doped a-Si0·7Ge0·3: H. Electron bombardment and annealing are used to vary the defect density and to shift the Fermi level in the range 0·45<EC–EF<0·75 eV. The main observation is that electron bombardment causes an enhancement of the density of hyperfine centres and a major decrease of the hyperfine splitting from 265 to 200G. The data show that phosphorus introduces two hyperfine centres: the well known fourfold coordinated phosphorus atoms Pi and a deep state the density of which can be enhanced by electron bombardment and hydrogen effusion. We suggest that the latter is a dangling-bond state on a twofold coordinated phosphorus (P02).

ISSN:0950-0839    

DOI:10.1080/09500838808214713

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This paper compares photbluminescence optical absorption, H-evolution, and infrared vibrational spectra of glow-discharge deposited hydrogenated amorphous silicon, a-Si:H, prepared in three different ways: continuous deposition and deposition interrupted hundreds of times either by a shutter or by shutting off the plasma power. The latter yields an excess hydrogen content, a blue shift of the optical gap, and a decrease in the photoluminescence intensity. The results are related to the initial non-equilibrium plasma chemistry.

ISSN:0950-0839    

DOI:10.1080/09500838808214714

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor