Vol. 33, No. 7 (1984)
1984-04-05
CONTENT
1984, 33 (7): 897-907.
doi: 10.7498/aps.33.897
Abstract +
By using Koster-Slater Green's function method and on-site defect potential approximation, a systematic method of A1 symmetric deep level wavefunction calculation of substitutional defect pairs is worked out. The method is applied to the spectator-oxygen pairs in GaP successfully. The Zn-O and Cd-O pair wavefunctions are obtained for the first time. The wavefunction is mainly concentrated on four bonds which locate at four nearest neighbour sites of oxygen center and point toward the oxygen. Nevertheless, the four bonds are not in the equal weight. The component of the bond which links spectator with oxygen is reduced in comparison with other three and it is more reduced for more electropositive spectator. The rest part of the wavefunction extends diversely over a wide range of space.
1984, 33 (7): 908-913.
doi: 10.7498/aps.33.908
Abstract +
We find that the amorphous alloy Ti80Si20 wouldn't decompose into multiphases, but rather transform directly into bcc supersaturate solid solution of Ti (Si). This phenomena may be attributed to the lower elastic energy created by solid solution and the comparatively large compressibility of Ti.
1984, 33 (7): 914-920.
doi: 10.7498/aps.33.914
Abstract +
In this work, the structures of crystalline phases formed from the amorphous Co80B20 alloy under pressures from ambinent pressure to 770 kbar has been investigated. The results obtained are compared with those on amorphous Fe-B alloys.
1984, 33 (7): 921-926.
doi: 10.7498/aps.33.921
Abstract +
The relationship between the annealing temperatures and the hydrogen-induced defects in floating zone silicon grown in hydrogen atmosphere has been investigated by X-ray section topography. According to the analysis of X-ray topographic patterns of the early stage hydrogen-induced defects, it is found that the lattices around hydrogen precipitates are under compression. The processes of the breakdown of silicon-hydrogen bonds and the formation of hydrogen-induced defects are discussed briefly.
1984, 33 (7): 927-934.
doi: 10.7498/aps.33.927
Abstract +
We have studied the saturation effect of degenerate four-wave mixing in Doppler-broadened two-level system. A set of recurrent formula which is suitable for numerical analysis is derived and applied to calculate the lineshape of four-wave mixing signal in the weak saturation region. The results show that a double-peak structure appears at the line center as the intensity of the incident light increases.
1984, 33 (7): 935-942.
doi: 10.7498/aps.33.935
Abstract +
The stationary pulse solutions for a free electron laser are obtained by using the classical theory. Computation shows that the stationary solutions can only be found under certain particular conditions. The shapes of the solutions do not depend on the shapes of initial optical pulses as long as these conditions are satisfied.
1984, 33 (7): 943-951.
doi: 10.7498/aps.33.943
Abstract +
The relationship of the conductivity with frequency for an amorphous fast lithium ion conducting material B2O3-0.7Li2O-0.7LiCl was studied. The results showed that: in a quite wide frequency range the bulk conductance was equal to the total conductance for the specimens; the frequency spectra of the conductivity showed a plateau and a rise in the intermediate and higher frequency range, respectively; and the frequency at which the conductivity began to increase became higher with rising of temperature. As a result of the features of such amorphous material, the measurement of the conductivity may be carried out by use of the a.c. bridge or the a.c. V-A method and thus be simplified. Considering the effect of the long range disorder in the non-crystalline solid on the ionic transport, we praposed a mechanism of the local polarization and explained the features of the spectra of conductivity and its dependence on temperature.
1984, 33 (7): 952-958.
doi: 10.7498/aps.33.952
Abstract +
The quantum diffraction of the superconducting weaklink and the quantum interference of the dc-SQUID have been calculated theoretically based on the constant current source ESJ modle. An analytical expression describing the constant amplitude oscillation of the dc voltoge component with magnetic field for double junction de-SQUID has been obtained.
1984, 33 (7): 959-966.
doi: 10.7498/aps.33.959
Abstract +
In this paper, the superconducting weaklink and the influence of the feed back radiation on its I-V curve is studied, based on the constant source RSJ model. The analytical solution has been obtained and the relationship between the change of the I-V curve and the feedback radiation field intensity from the cavity has been given for the case while the field is very weak. The theoretical results show that the feedback radiation can change the amplitude and shape of V(H), but its period is unchanged.
1984, 33 (7): 967-974.
doi: 10.7498/aps.33.967
Abstract +
The McMillan tunneling model has been generalized and applied to a N-S multi-film structure with thickness of each film smaller than the superconducting coherent length. The order parameters and superconducting critical temperature of the structure are calculated, and the possibilities of enhancing Tc by modifying the electron-phonon coupling and contaminating with different atom in the interface regions are also discussed.
1984, 33 (7): 975-988.
doi: 10.7498/aps.33.975
Abstract +
A formula of the critical temperature for superconductors with small λ is derived from the Eliashberg equation. The effective phonon spectrum is taken in the present paper as the Einstein spectrum. The values of Tc calculated from our formula are compared with the numerical solutions of the Eliashberg equation in the case of μ*= 0 and the agreement between them is fairly well in the region of λ<Λ.
1984, 33 (7): 989-998.
doi: 10.7498/aps.33.989
Abstract +
The micro-diffusion equation for Zener pairs and asymmetric pairs of point defects in fcc metals under the action of periodic distributional moving sources of inner stress have been solved by using finite Fourier transformation and Laplace transformation. Finite sum formulae for rigidity and damping coefficient of a kink have been obtained.Numerical results are given. A simple analytic result is obtained for anelastic interaction between edge dislocation and asymmetric pairs of point defects, which is found to be in agreement with other results based on a different approach.The enhanced internal friction due to the interaction between dislocation and point defects is discussed.
1984, 33 (7): 999-1007.
doi: 10.7498/aps.33.999
Abstract +
The set of coupled, self-consistent equations for the order parameter, the fermion field and the collective excitations developed previously in the framework of the closed time-path Green's functions (CTPGF) is applied to systems with four-fermion interaction. The Hartree, the Hartree-Pock (HP) and the random phase approximations (RPA) for the order parameter and its fluctuations are derived in a systematic way. The thermodynamical potential for the fermion system is calculated explicitly in these approximations. The formalism presented here can be applied to nuclear as well as other many fermion systems in both equilibrium and nonequilibrium states.
1984, 33 (7): 1008-1016.
doi: 10.7498/aps.33.1008
Abstract +
Detailed numerical study shows that along certain directions in the parameter space the periodicity of the forced Brusselator appears in the same order as that in one-dimensional nuimodal mappings, i.e. in accordance with the U-sequence of Metropolis, stein and Stein. We find a simple method to assign words from a symbolic dynamics of two letters to periods in the model. Our results show the neccesity to enlarge the parameter space in similar research ia order to have a global picture of the bifurcation and chaos "spectrum".
BRIEF REPORT
1984, 33 (7): 1017-1023.
doi: 10.7498/aps.33.1017
Abstract +
The following spectra of LiYF4:Nd have been observed for the first time: (i) the electronic and electron-phonor Raman spectra of the stark sub-levels Y1-Y6 of energy levels 4I11/2 excited by 4880? Ar+ laser beam; (ii) two-photon fluorescence and electron-phonor spectra excited by 6943? ruby laser beam.
1984, 33 (7): 1024-1030.
doi: 10.7498/aps.33.1024
Abstract +
This paper reports the process of bifureation to chaos of the self-pulsing output with the changing of the parameters of the system in a liquid crystal hybrid optical bistable device under the condition of tR>>τ (where tR is the delay time of the feedback system, τ is the relaxation time of the liquid crystal). The bifurcations and chaos are calculated. The dynamical behavior of the system is analysed by the Fast Fourier Transform and the phase portrait. The experimental result is compared with Ikeda's theory.
1984, 33 (7): 1031-1036.
doi: 10.7498/aps.33.1031
Abstract +
The pitch of the mixture MBBA:CC=22.7 :77.3 (by weight) at different tempera-lures ranging from 37℃ to 55℃ is determined by method of Bragg scattering using 6328? He-Ne laser beam. From the present measurement and the published data on other materials, we propose an empirical formula for the temperature dependence of the pitch of cholesterics, namely p=p0-b/(T-T0), with the pitch p0 for dextrorotatory materials. This formula is well suited not only for pure materials but also for mixtures as long as the temperature is not very close to the point of transition or the point of inversion of the helicity of the materials. The constants p0 ,b and T0 for different cholesteric liquid crystals are determined from their related data.
1984, 33 (7): 1037-1039.
doi: 10.7498/aps.33.1037
Abstract +
By tilting the crystals formed in an amorphous Ni-P alloy during crystallization in transmission electron microscope, two further hexagonal metastable phases (a2 and a3) have been discovered. Their lattice parameter a has the same value (6.73?) as that of the previously reported hexagonal metastable phase (a1), but the values of the other lattice parameter c are 3/2 and 4 times respectively of that of the phase a1. This shows that these phases are longperiod polytype structures. Furthermore, the previously assumed F.C.C. sublattice (a=5.50?) of a1 has been found to be really metastable phase from {111} planes of which these hexagonal metastable phases are formed.
1984, 33 (7): 1040-1043.
doi: 10.7498/aps.33.1040
Abstract +
During the martensitic transformation of Co-Al alloys stacking faults occur abundantly and sometimes a local ordered 21R structure can be found by electron diffraction and lattice imaging techniques. It is shown that optical diffraction method is a useful means of studying this kind of local ordered structure.
1984, 33 (7): 1044-1049.
doi: 10.7498/aps.33.1044
Abstract +
This paper supposes that N=8 Extended Supergravity (ESG) can form the composite supermultiplets, and discusses the possibility of containing SU(5) Supersymme-tric Grand Unification Theory (SUSY GUT) in both composite supermultiplets {3/2,8}N=8SU(8) and {2,28}N=8SU(8) Under some harsh assumptions, it is possible to obtain 3 generations of leptons and quarks and satisfactory particle spectrum of SU (5) SUSY GUT in the {3/2,8}N=8SU(8) scheme. Under some reasonable assumptions, it is possible to obtain 5 generations of leptons and quarks (or after some modification, 4 generations) in the {2,28}N=8SU(8) scheme.
1984, 33 (7): 1050-1057.
doi: 10.7498/aps.33.1050
Abstract +
The analytic expressions of local damping rate of ordinary and extraordinary modes in perpendicular propagation have been obtained on the basis of the general expressions of the dielectric tensor for the weakly relativistic anisotropic Maxwellian distribution function. The effects of the anisotropy of the distribution function and loss cone type distribution function on the local damping rate have been discussed.
LETTERS
1984, 33 (7): 1058-1061.
doi: 10.7498/aps.33.1058
Abstract +
Following the line of our interpretation of the conduction behavior of metallie su-perlattices, we have studied the attenuation of sound waves in such artificial materials, with special emphasis on the dependence upon the modulation wavelength. Acoustical experiments may help to justify the physical mechanism of transport processes suggested in [1].
1984, 33 (7): 1062-1064.
doi: 10.7498/aps.33.1062
Abstract +
The process for making Chevrel-phase PbMo6S8 superconducting tapes by reaction diffusion method and the properties of the tapes are reported. Mo tape reacts with H2S to form single phase Mo-S compound (MoS2 or Mo2S3, depends on the reaction temperature), then with Pb vapor to form single phase PbMo6S8 layers. The transition temperature of the layers are 13.0-14.5 K, the widths of the transitions are in the range of 0.15-0.20 K and Jc(6T, 4.2K) ≌1.9×l08A/m2.
