摘要:

AbstractA theoretical expression for the energy shift of the resonant absorption of γ‐rays by a disordered lattice has been derived using the double‐time Green's function and taking a simplified model of a vacancy and an interstitial pair in the lattice. Considering only nearest‐neighbour interactions in the harmonic approximation it has been found that in addition to the energy shift due to the second‐order Doppler effect there is an additional shift due to the disordering of the lattice which depends on the position coordinate of the interstitial atoms, the changed force constant of this atom, and the tem

ISSN:0370-1972    

DOI:10.1002/pssb.2220490131

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractX‐ray diffraction patterns have been obtained from liquid metals (Al, Ga, In, Tl, Pb, Sn, Bi) near the melting point. After calculating the structure factor (Fourier analysis), the atomic radial distribution function was evaluated from which interatomic distance and coordination number were obtained. It has been shown that the ratio (K2/K1) of the position of the first peak (K1) to that of the second peak (K2) in the structure factor is a very useful parameter to represent the structure of liquid metal

ISSN:0370-1972    

DOI:10.1002/pssb.2220490132

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractIn a previous paper the problem of the non‐magnetic impurities in metals has been discussed and the deviations from the Matthiessen relation have been calculated. However, the effect of localized modes was not considered there. In the present paper a more general theory which includes the effect of local modes has been presented. The problem of the localization of the electrons has also been discusse

ISSN:0370-1972    

DOI:10.1002/pssb.2220490133

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe experimental results of detailed electro‐optical studies on Z1centers in KCl doped with Ca, Sr, and Ba are reported. For randomly oriented Z1center systems an isotropic quadratic Stark effect is measured, with a spectral dependence (close to a third derivative of the Z1absorption) markedly different from that of F centers. The equality of the Z1center orientations can be disturbed by the application of de fields (about 104Vcm−1) above 120°K, leading to the development of a linear Stark effect. The spectral dependence and characteristic anisotropy of this linear Stark effect are determined. Quantitative pulse annealing experiments under applied de field show that the Z1centers reorient with an activation energy of ≈0.4 eV. This process is attributed to jumps of the cation vacancy among equivalent lattice sites within the Z1complex and will be discussed on the basis of a vacancy‐centered model proposed ear

ISSN:0370-1972    

DOI:10.1002/pssb.2220490134

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractIsolated paramagnetic Cr+centres in sodium halide crystals are studied by EPR and ENDOR. They show cubic symmetry. Superhyperfine and quadrupole interactions with many neighbouring ions (up to 〈300〉 in NaF) could be determined. The experimental results are interpreted in terms of two models for the wavefunction of the centre: overlap and covalency. A new way for the experimental determination of the coefficients for σ‐ and π‐covalency, using the isotropic superhyperfine interactions of neighbours 〈110〉 and 〈200〉, is proposed. The small anisotropic superhyperfine interaction of the nearest neighbours, which becomes even negative for Br−in NaBr, cannot be understoo

ISSN:0370-1972    

DOI:10.1002/pssb.2220490135

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

摘要:

AbstractThe investigation of the Hall coefficient in CdxHg1−xTe under hydrostatic pressure over the temperature range 77 to 300 K is reported. It is shown that within the experimental error, the energy gap is linear withxin the range 0

ISSN:0370-1972    

DOI:10.1002/pssb.2220490136

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY

ISSN:0370-1972    

DOI:10.1002/pssb.2220490101

出版商:WILEY‐VCH Verlag    

年代:1972

数据来源: WILEY