Vol. 35, No. 8 (1986)
A COMPUTER SIMULATION OF THE STRUCTURE OF AMORPHOUS ALLOY Ni64B36 (Ⅱ)——THE INFLUENCE OF THE BOUNDARY ON THE STRCTURE OF THE MODEL
1986, 35 (8): 969-978. doi: 10.7498/aps.35.969
The model that we have made to simulate the structure of Ni64B36 is taken as the primary configuration. This configuration is then subjected to relaxation under the free boundary, the confined boundary, the periodic boundary and the quasi-dynamical equilibrium boundary through the Morse potential. The energy minimisation method used here is different from that usually taken by other authors in some respects. By comparing and analysing the change of some structure parameters in relaxation, the influence of each kind of boundary on the structure of the model is discussed.
EFFECT OF W ADDITION ON MAGNETIC, ELECTRIC PROPERTIES AND THERMAL STABILITY OF AMORPHOUS Fe-B ALLOYS
1986, 35 (8): 979-988. doi: 10.7498/aps.35.979
Effect of W addition on Curie temperature TC, thermal stability and temperture coefficient of resistivity of amorphous Fe-B alloys are studied. The decrease of TC and increase of thermal stability in amorphous (Fe1-xWx)84.5B15.5 alloys with increasing W content are discussed. The change of the resistivity with increasing temperature can be interpreted in terms of the phonon and the local spin fluctuation scattering.
The hydrogen content in γ-Fe2O3 was determined by thermal neutron transmission method. The phase transformation of γ-Fe2O3 was studied with D. T. A., magnetic analysis and Mossbauer effect. The presence of hydrogen in the crystal structure of γ-Fe2O3 was ascertained by the experimental results. The crystal structure of γ-Fe2O3 become more stable and the transformation temperature from γ-Fe2O3 to α-Fe2O3 will increase when the cation vacancy of γ-Fe2O3 was occupied by H1+, Co2+, Si4+, P5+ ions etc.
1986, 35 (8): 995-1001. doi: 10.7498/aps.35.995
The solubility range of Al in R2(Fe1-xAlx)14B, R=Nd and Y, have been determined. They crystallize in the tetragonal structure when x2Fe14B by substituting properly Fe with Co and Al.
In this paper, the sine-squared potential is introduced, and the motion equation of particle is reduced to a pendulum equation. with constant moment; the propeties of the phase plane are described in detail by using the method in nonlinear mechanics, the effects of the singular point distribution and motion in phase plane on stability of the system are discussed, the critical parameters and maximum energy are deduced. Besides, the particle motion behaviours in the case of small amplitude approximation is analyzed. The results show that the system appears to exhibit soft-spring properties. The solution and the period are represented exaclly by Jacobian elliptic function and the 1-st kind of complete ellrptic integral. The space distribution and momentum distribution of particles are derived.
1986, 35 (8): 1010-1018. doi: 10.7498/aps.35.1010
In order to investigate the transport processes of carriers in the amorphous semiconductor superlattices, we have proposed and rigorously solved the continuous-time random walk model in the form of superlattice for the migration of carriers. Being based upon this, the generalized form of the Pick's law in these materials has been obtained, and the mobility of carriers, varying with the frequency and the modulation wavelength, has been calculated for the Gaussian and non-Gaussian time-distribution functions respectively. It has been shown that the long-time-tail behaviour (for the non-Gaussian distribution) may partly cancel the size-effect due to the structural modulation.
1986, 35 (8): 1019-1028. doi: 10.7498/aps.35.1019
This article deals with the low-lying electronic states——the charge transfer excitons(CTE), of alkali halide crystals. By the standard perturbation method of degenerate states, the energy spectra of the CTE are studied and the effective Hamiltonian of the CTE system is derived. The energy levels of the CTE obtained by numerical calculations agree with the peak positions of light absorption spectra found in the literature, the relative errors are small. In this article, the bandwidth and the effective transla-tional mass of the CTE are also obtained.
1986, 35 (8): 1029-1039. doi: 10.7498/aps.35.1029
In this article, taking the exciton and polar-phonon interaction as an example, we introduce an integral operator to deal with the dynamical problem of exciton-phonon interaction. Compared with the methods of earlier arthors, our method has some characteristics : besides the binding energies which agree with the measured data of experiments, the lifetime of excitons, the renormalization factors of translational masses, and the relation between these quantities and temperature, are obtained simultaneously. This method may be used not only for the Is state, but also the states higher than Is state. Furthermore, this method may be extended to the anisotropic case and the case of degenerate valence band conveniently.
1986, 35 (8): 1040-1047. doi: 10.7498/aps.35.1040
In this paper, a theoretical model describing the surface superfluidity in 4He-3He mixture films is proposed to obtain an expression for the potential energy of vortex pairs in the presence of 3He. The static recursion relations as well as the dynamical delectric function are then derived using this form of potential energy. The period shift 2△P/P and the dissipation Q-1 for the torsional oscillator near TC are calculated theoretically and compared with the experimental results of McQueeney et al.
1986, 35 (8): 1048-1054. doi: 10.7498/aps.35.1048
We propose a generalized Ising spin model, which contains the pure Ising model, the mixed spin model proposed by Schofield and Bowers and the particular site-diluted Ising spin model as special oases. A real space renormalisation group is applied to this model, the phase diagram is found to have three nontrivial fixed points (a Ising, a tric-ritical and a first order phase transition point). And it is demonstrated that mixed spin model and pure Ising spin model belong to the same universality, which is in agreement with the conclusion made by Schofield and Bowers who calculated the critical exponents of mixed model directly.
1986, 35 (8): 1055-1061. doi: 10.7498/aps.35.1055
A variational method proposed by Wilets et al. is used to calculate the eigenvalues and eigenfunctions for the (ls)22p2P, (ls)23s2S, (ls)23p2P, (ls)23d2D and (ls)24f2F states of the lithium. The results are compared with those obtained from Hartree-Fock method, CI method and 1/Z expansion method.
1986, 35 (8): 1062-1071. doi: 10.7498/aps.35.1062
In this paper, we suggest a Lagrangian which is invariant under the general coordinate transformation and local Lorentz transformation. The dicussion is focused on its classical Lagrangian equation of motion and the canonical formalism corresponding to this Lagraugian.
1986, 35 (8): 1072-1076. doi: 10.7498/aps.35.1072
A series of magnetic modes were observed in LPE YIG films magnetized in plane. These magnetic modes were excited by means of magnetostatic wave excitation and show characterisitics of equal spacing and slower attenuation than normal standing spin waves. Considering that the precession is elliptical and supposing there are inhomogenuity of magnetization in the film, we deduced relation between mode spacing and magnetic parameters of YIG. Comparing with experiments, an inhomogenuity of 2.6—5.8% were deduced for our LPE YIG films.
1986, 35 (8): 1077-1080. doi: 10.7498/aps.35.1077
The experimental results of X-ray photoelectron spectroscopy for amorphous (Fe1-x Cox)78 Si9.5 B12.5 alloys are reported. The Co-content dependence of the binding energy of the inner electrons in Fe, Co, Si and B element and the density of states at the Fermi surface in these alloys are presented.
1986, 35 (8): 1081-1086. doi: 10.7498/aps.35.1081
We measured R-T characterization of various Sn granular film samples at low temperatures. The samples were prepared by using thermovaporization method in a vacuum chamber containing oxygen.Because of the grains and the grain sizes and the distance between the grains are randomly distributed, the Josephson coupling and the thermal excited electrons of hopping process between the grains are not identical for different samples. So the experimental results may be recognized as the following three kinds of processes: (1) transition to zero resistance; (2) minimum resistance; (3) metal-insulator transition.
1986, 35 (8): 1087-1090. doi: 10.7498/aps.35.1087
On the basis of the references [1-3], we carried out a series calculation for all order (practical) transverse modes in axial-symmetric resonators used in common lasers. The calculations covered symmetric and asymmetric, stable and unstable resonators. All of the important characteristics of 10790 transverse modes in 673 resonators with Fres-nel number ?≤ 5 (individually ?=8, 10) were obtained.
1986, 35 (8): 1091-1094. doi: 10.7498/aps.35.1091
The mechanism of creep-fatigue interaction in a nickel base alloy (Nimonic 75 type) has been studied by transmission and scanning electron microscopy. Experiments at 873 K and a stress amplitude 392 MPa showed that, the data of creep, fatigue and "creep combined with fatigue" obeyed approximately the linear cumulative law. Micrographs of fracture surfaces by SEM indicated that, the rupture was all intergranular. However, observations by TEM showed that, the dislocation configurations within fractured specimens were quite different among creep, fatigue and "creep combined with fatigue". We believe that different dislocation configurations have different influence on the process of intergranular rupture, and the damages due to creep and fatigue are independent with each other. Consequently, linear interaction between creep and fatigue occurs macroscopically. The present paper shows that TEM has great potentialities for revealing the mechanism of creep-fatigue interaction.
1986, 35 (8): 1095-1101. doi: 10.7498/aps.35.1095
The theory of instability for non-linear differential equations is applied to the rate equations of a bistable laser. It is found that there are three conditions have to be fulfilled in order to make the system stable. The first condition is automatically fulfilled for ordinary bistable lasers. The second and third conditions are related to self-pulsation and bistable characteristics of the laser respectively. It has been shown that if the third condition is not fulfilled in certain region, the linearized rate equation for small-signal will have a monotonously increasing solution in that region. This means that the light power output curve has a negative slope region, which would result in bistable character. On the other hand, if the second condition is not fulfilled, the linearized rate equation for small-signal will have enhanced oscillating solutions. This means that the laser will self-oscillate as long as the third condition is fulfilled in that region. Besides, it is also shown that both the self-pulsation and the bistable behaviours of the laser are closely related to the non-linearity of g(N) function, which is the necessary condition for having a linearized rate equation of third order.
1986, 35 (8): 1102-1107. doi: 10.7498/aps.35.1102
The position of H atom in the crystal K2H(IO3)2C1 was determined by neutron diffraction. 481 refletions were collected including 355 independent ones. Both programs of SHELX and OR XFLS4 were used to perform Fourier and difference Fourier syntheses and the least square refinement (with isotropic and anisotropic extinction correction). The final R value was 3.3%. The results make sure of the existence of the hydrogen bond in the crystal.
THE RELATIONSHIP AMONG CHEMICAL COMPOSITION,CRYSTAL STRUCTURE AND IONIC CONDUCTANCE IN Na3Zr2-xInxSi2-xP1+xO12 SYSTEM
1986, 35 (8): 1108-1114. doi: 10.7498/aps.35.1108
Na3Zr2-x InxSi2-xP1+xO12 system has been investigated by means of solid state reaction, X-ray powder diffraction technique, microscopic observation, specific heat measurement and complex impedance measurement. There are two kinds of solid solutions in this system: monoclinic solid solution (0≤x3Zr2-xInxSi2-xP1+xO12 solid solution, which begins at the composition of x=0.8, has been stabilized at room temperature. The stabilized materials do not exhibit any phase transformation in the heating process. The electrical conductivities in Na3Zr2-xMxSi2-x P1+x O12 (M = Y, Yb and In) systems have been compared, and discussed from the point of view of crystal chemistry.