ISSN:0370-1972    

DOI:10.1002/pssb.2221970229

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA quantitative evaluation of the dislocation energies in relation with the β → 18R martensitic transformation in Cu‐Zn‐Al alloys has been performed. Dislocations produced by macroscopic deformation of the parent or martensitic phase have been considered. The crystallographic changes of the dislocations upon transformation have been established and the anisotropic theory of dislocations has been used to calculate their energy when embedded in β or martensite. Good agreement was found between the calculated separation of the partials and the corresponding line orientations for the minimum energy and the experimental results from transmission electron microscopy obser

ISSN:0370-1972    

DOI:10.1002/pssb.2221970202

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe peculiarities of colour centre production and recombination in KBr, KI crystals doped with Tl, In are examined. The photostimulated dopant ion luminescence (PSL response) follows that of the F‐centre production in the subnanosecond time range. It is concluded that the radiation defects in a doped crystal are spatially distributed in the near vicinity of the dopants. To a limited extent the photo‐ and thermostimulated defect recombination also takes place near the dop

ISSN:0370-1972    

DOI:10.1002/pssb.2221970203

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDiffusion of iron in DO3ordered Fe76Si24has been studied under hydrostatic pressure at 934 K. The diffusion coefficients were determined using the radiotracer technique with the implanted radioisotope59Fe and a precision grinding device for serial sectioning. The resulting activation volume of diffusion is ΔV = 1.48 × 10−29m3= 1.27Ω (Ω atomic volume). The large value of ΔV can be attributed to vacancy‐mediated Fe diffusion, in which divacancies or even larger vacancy clusters might be involved. This assumption is corroborated by positron annihilation experiments, which show a strong increase of the lifetime of trapped positrons in Fe75Si25at higher temp

ISSN:0370-1972    

DOI:10.1002/pssb.2221970204

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA reformulation of the solute/solvent diffusion enhancement problem is discussed by introducing a new set of two empirical parameters. A comparison with experimental data, both for solvent and solute enhancements, shows good agreement. A constant u is introduced relating the preexponential factor and the activation energy in the Arrhenius equation for the diffusion coefficient. This constant is attributed to the solute/solvent enhancement‐reduction transition temperatur

ISSN:0370-1972    

DOI:10.1002/pssb.2221970205

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe far‐infrared reflectivity spectra of Hg1−xMnxS (x= 0.02, 0.05, 0.10, 0.20, 0.25, and 0.33) alloys were measured in the 30 to 500 cm−1spectral range at different temperatures and analyzed using a numerical fitting procedure based on the plasmon‐phonon interaction model. The three active modes at about 125, 189, and 305 cm−1are clearly observed. These modes were assigned as twophonon resonant mode, zone center phonon mode, and disorder‐activated mode, respectively. It was shown that phonons in Hg1−xMnxS alloys (for Mn concentrationsx≤ 0.33) exhibit on

ISSN:0370-1972    

DOI:10.1002/pssb.2221970206

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractWithin the framework of an approach with allowance for fluctuations of the mean energy of a particle interacting with a thermostat, the partial density of vibrational states (PDVS) of a crystal lattice defect located in a two‐well potential has been investigated. The results obtained are in good agreement with those of a numerical study of the corresponding Langevin equation. It has been shown that the mass dependence of the anharmonic defect PDVS is quite complicated and is determined by temperatur

ISSN:0370-1972    

DOI:10.1002/pssb.2221970207

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA qualitative analysis of lattice vibration effects including lattice distortions, spin‐phonon interaction, and phonon anharmonicity is given within the extended transverse Ising spin model (TIM). It is argued that the rigid‐lattice TIM is a credible model for real crystal in the sense that no new anisotropic‐type interactions emerge due to higher‐order lattice distortions. Instead of the known first‐order Kobayashi model a new effective second‐order nonrigid‐lattice TIM is proposed. Recent developments in the TIM spin dynamics are brie

ISSN:0370-1972    

DOI:10.1002/pssb.2221970208

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe microhardness of Ge‐Sb‐Se, Si‐As‐Te, and Ge‐As‐Te glasses has been studied as a function of the average coordination number 〈r〉. A step‐like increase is observed in the Vickers hardness number (VHN) above 〈r〉 = 2.30 in Ge‐Sb‐Se glasses, and above 〈r〉 = 2.50 in Si‐As‐Te and Ge‐As‐Te glasses. This behaviour can be interpreted on the basis of the occurrence of a mechanical and chemical threshold in these glassy systems. The applicability of this technique to measure the elasto‐plastic properties of small and brittle samples such as tellurium‐

ISSN:0370-1972    

DOI:10.1002/pssb.2221970209

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe influence of an intense high‐frequency laser field on the binding energy of a shallow neutral donor impurity in a quantum semiconductor structure such as GaAs/AlGaAs is reported. By making use of a nonperturbative theory and the variational approach it was found that for an on‐centre hydrogenic impurity in the given quantum well, the binding energy for different well widths increases, reaches a maximum, and then decreases quite rapidly with increasing laser field amplitude of the quiver motion of the elect

ISSN:0370-1972    

DOI:10.1002/pssb.2221970210

出版商:WILEY‐VCH Verlag    

年代:1996

数据来源: WILEY