摘要:

AbstractThe third order elastic constants and the pressure derivatives of second order elastic constants of ternary zinc blende semiconductor, CuGe2P3are analysed using two theoretical approaches. The first model consists of Born‐Mayer type short‐range potential in addition to the long range many‐body interaction and Coulomb potentials, while the second model is derived from Martin's bond‐bending and stretching force model. It is shown that although the bond bending force model gives a reasonably good fitting to these properties, the present model including three body forces explains adequately the features of the anharmonic behaviour reasonab

ISSN:0370-1972    

DOI:10.1002/pssb.2221370206

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractSeven different potential forms for the overlap repulsive energy proposed by various investigators as reported in the literature are examined for the fluorite‐structure crystals, viz. CaF2, SrF3, BaF2, PbF2, Sr(NO3)2, Ba(NO3), and Pb(NI3)2. A number of crystalline state properties such as cohesive energy, bulk modulus and its pressure derivatives, Grünesien und Anderson parameters, first and second order volume and pressure derivatives of dielectric constants are calculated using different potential functions. The results obtained are found to compare well with available experimental data, and also reveal the usefulness of the approach based on interionic potentials in predicting new resul

ISSN:0370-1972    

DOI:10.1002/pssb.2221370207

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe dynamics of thermally activated unpinning of dislocations from point defects under the action of an applied stress is studied. It is shown that the Fokker‐Planck infinite‐dimensional equation describing the diffusion of a particle in the configurational space is reduced to a one‐dimensional one in the concentrated‐force approximation. Moreover it is shown that over a wide range of parameters dislocation unpinning from the point defect occurs in two stages: at the first stage the dependence of the unpinning probability on the initial configuration of a dislocation disappears and at the second stage the system, passes from one stationary state to another. Characteristic times of the problem are found, and their dependence on temperature and dislocation length are

ISSN:0370-1972    

DOI:10.1002/pssb.2221370208

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe relative ordering of the dimerized patterns of neighboring Wolffram's red salt chains is studied with a model where the coupling is due to the interchain Coulomb interaction. It is shown that this mechanism favors antiferromagnetic order between neighboring chains. It also leads to bound domain wall pairs on the same chain. The energy associated with a pair of domain walls increases asymptotically linear with its length.

ISSN:0370-1972    

DOI:10.1002/pssb.2221370209

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe value of 9.27 × 10−23J for the exchange coupling parameter between the Ho and Co spins in Ho2Co17has been derived. Some experimental evidence is given to show that the R–T spin coupling parameter is rather insensitive to the kind of the rare earth atom as well as on the cobalt composition. It allows to calculate the intersublattice molecular fields for the rare earth–cobalt intermetalic compounds. This field affects the R magnetic moment and originates from the Co sublattice in the R2Co17, RCo5, R2Co7, RCo3, and RCo2compounds. The fields in the new magnetic materials of the R2Co14B type have also been eva

ISSN:0370-1972    

DOI:10.1002/pssb.2221370210

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA Monte Carlo simulation of the electron emission induced in NaCl by 60 to 250 eV photons is carried out. The number as well as the initial energy and spatial distribution of conduction electrons, obtained in a previous paper, are used as the input. Electron–phonon scattering events are treated semiclassically. Optical as well as acoustical phonons are taken into account, so that with the increase of electron energy the scattering probability decreases for optical and increases for acoustical phonons. The parameters of the model are adjusted to fit the experimental quantum yield and energy spectra of emitted electrons. It appears that for high‐energy (>2 to 3 eV) electrons the electron–phonon scattering is mainly due to acoustical ph

ISSN:0370-1972    

DOI:10.1002/pssb.2221370211

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA perturbation theory is developed for the kinetic coefficient of the electron transfer from donor molecules (Dm) to acceptor molecules (Al) along a one‐dimensional molecular chain to whichDmandAlare statistically joined. The influence of donors and acceptors to the soliton states is reflexed to the value of corresponding kinetic coefficien

ISSN:0370-1972    

DOI:10.1002/pssb.2221370212

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractAn analysis of the Ti K edge and Ta L edges yields that the chemical shift amounts to 0.8 eV by a valence charge increase. An exciton line is resolved like in other rutiles. Exciton binding energy amounts to 1.1 eV and decreases to 0.6 eV for high tantalum content. The coordination polyhedron size of titanium increases to 11 × 10−3nm with the tantalum content. This is essentially due to the increase of ionic radius of titanium by the valence charge increase. The crystal field splitting is found to be 3.1 eV for TiIV, 2.1 eV for TiIII, and (5.5 to 6.0) eV for TaV. It seems that the crystal field splitting is well correlated with the valence charge. Additionally a procedure is described to add several × absorption spectra recorded on several samples with the same composition but with different thicknes

ISSN:0370-1972    

DOI:10.1002/pssb.2221370213

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA model is deduced for the electronic structure of the Ce systems. It includes a pseudopotential which considers the strong correlation effects due to the fluctuation of the number of f‐electrons in the Ce atoms. The pseudopotential affects the f‐symmetries according to their own occupations and is different from zero when the f‐states are spd/f hybridized. The APW method is modified in order to introduce the pseudopotential within the band structure Hamiltonian. Finally, the so‐called „three‐peak”︁ 4f structure which appears in the Ce systems is analyzed

ISSN:0370-1972    

DOI:10.1002/pssb.2221370214

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of non‐spherical part of the crystal potential on the band structure of dysprosium metal in the warped muffin‐tin approximation has been studied using the augmented plane wave method. The band structure is not significantly affected by this factor in the present case. The maximum change in energy eigenvalues is 0.002

ISSN:0370-1972    

DOI:10.1002/pssb.2221370215

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY