摘要:

AbstractThe limit volumic electrostatic energy of a crystal lattice of point charges is compared to the Born‐Landé expression and to the Ewald energy. Conditions are given about the existence of these energies, and the results are expressed in an integral form; a second integral form is obtained by application of Plancherel's theorem. The volumic electrostatic energy depends on the surface of the crystal (owing to the long‐range I/rdependence of the electrostatic energy). Information about the atomic configuration of the surface of the crystal, is obtained by minimization of the volumic energy (the minimum being the Ewald ene

ISSN:0370-1972    

DOI:10.1002/pssb.2221380209

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractResults of Raman studies of BiLiF4and YLiF4single crystals at 300, 77, and 4.2 K and powder pellets of these materials at 300 K are reported. The observed vibrations are assigned to the irreducible representations of the space group of the crystals.

ISSN:0370-1972    

DOI:10.1002/pssb.2221380210

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractQuantumstatistical calculations are made of transition probabilities for reactive processes on solid/liquid interfaces, which are assisted by multi‐phonon‐transitions of the surrounding medium. A joint treatment of a classical (solvent) and a quantal (lattice) part of the medium effect upon reactive transitions is given. Numerical calculations are carried out in different approximati

ISSN:0370-1972    

DOI:10.1002/pssb.2221380211

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe mobility of a dislocation in metals at low temperatures is limited by the damping due to conduction electrons. The kink model of a dislocation is pursued in order to study this damping force and hence the mobility. Calculations are presented for one, two and three dimensions. The dependence of the mobility and electron density is exhibited for different dimensions. New results are derived.

ISSN:0370-1972    

DOI:10.1002/pssb.2221380212

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThree glow peaks around 320, 370, and 410 K are observed for X‐irradiated BaFCl:Dy and BaFCl:Cu. Optical bleaching effects on both glow peaks and F centers suggest that the thermal decay of F(Cl−) centers is not directly related to the 370 and 410 K peaks. Emission spectra indicate that the luminescence centers of these peaks of BaFCl:Dy can be attributed to Dy3+ions. On the basis of concluding the luminescence centers to be Dy3+, the glow peak reactions are proposed tentativ

ISSN:0370-1972    

DOI:10.1002/pssb.2221380213

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractTwo centers with tetragonal symmetry and principal axes along 〈100〉 are observed by ESR in single crystals of CaO. The ESR signal intensity of both the centers is affected by visible light illumination. One center (g∥ = 2.0048,g⟂ = 2.0007) occurs in highly colored crystals and may be associated with carbon impurities introduced during crystal growth. The other (g∥ = 1.99905,g⟂ = 1.99956) occurs in “clear” crystals after 1 MeV electron irradiation and has the characteristics of an anion–cation vacancy pair center containing one electron (i.e. a P−or F c+center). Theg‐values do not agree with those found for the same center in polycrystalline CaO but are consistent with a simple model

ISSN:0370-1972    

DOI:10.1002/pssb.2221380214

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe standing spin‐wave spectrum is analysed for the uniaxial ferromagnetic thin film with nearest‐neighbour and next‐nearest‐neighbour exchange interactions. The boundary conditions are described in terms of the uniaxial surface anisotropy. It is found that the nnn exchange interactions give rise to new types of bulk and surface spin‐wave modes. The properties of the new modes are discussed in their dependence on both, nnn coupling and surface anisotropy p

ISSN:0370-1972    

DOI:10.1002/pssb.2221380215

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA damping of spin waves is considered near the orientational phase transition (OPT) in the easy plane ferromagnet in an external magnetic field using the diagram technique for the Hubbard operators. It is shown that in the normal phase where uniaxial symmetry is not broken the damping takes place for nonzero temperature and increases with approaching the OPT point. In the broken symmetry phase the damping of spin waves takes place even atT= 0 and increases with going away from the OPT point.

ISSN:0370-1972    

DOI:10.1002/pssb.2221380216

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA new model of the temperature‐induced metamagnetic phase transitions is considered for the class of the two‐sublattice magnets with axial symmetry. The model Hamiltonian contains the usual Ising term as well as the coupling of the uniform strain with both exchange interaction and single ion anisotropy. Within the MFA all these couplings are found to be necessary to produce the metamagnetic phase change. The results are compared with experim

ISSN:0370-1972    

DOI:10.1002/pssb.2221380217

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractIt is shown that below a critical dimensiondc= 4 higher‐order random‐field cumulants contribute to the divergent part of the free energy. They renormalize the standard diagrammatic expansion into the most divergent terms in weak random fields in such a way that the perturbative effective dimensionality in the scaling region of thed<4 model is two. It is argued that any dimensional reduction based on a diagrammatic expansion is doubtful in lower dimensi

ISSN:0370-1972    

DOI:10.1002/pssb.2221380218

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY