Vol. 30, No. 6 (1981)
1981-03-20
CONTENT
1981, 30 (6): 709-714.
doi: 10.7498/aps.30.709
Abstract +
The crystal of cerium pentaphosphate with composition CeP5O14 belongs to monoc-linic system. The lattice parameters are as follows:α=8.797?, b=9.074?, c=13.124?, β=89°36′, Z=4. The space group is C2h5-P21/c. The diffraction data were collected using PW-1100 four-circle diffractometer. The number of independent diffraction data amounts to 2051. The structure is solved by heavy-atom method. Structure parameters were refined by full-matrix and block-diagonal least squares to a final R = 0.097. The result of structure analysis establishes that the structure is built up with discrete anionic ribbons linked by the cations in a complicated way. The polyhedral coordination of slightly distorted square antiprism is formed by eight oxygen atoms surrounding the Ce-cation. The shortest distance between two Ce ions is 5.967?.
1981, 30 (6): 715-721.
doi: 10.7498/aps.30.715
Abstract +
The molecular orbitals of (NO2)-1 grouping were calculated by using the all-valence electron semiempirical CNDO/S method. A general computer program for grouping theory of non-linear optical (ffects was then used to calculate the SHG coefficients of NaNO2. The agreement between the calculated values and the experimental ones was. found to be quite satisfactory without introducing any adjustable parameters. The results show clearly that the anisotropy of SHG coefficients of NaNO2 crystals is primarily due to the π molecular orbitals of (NO2)-1 grouping. The two-level model of SHG effects as well as its limitations have also been discussed in this paper.
1981, 30 (6): 722-730.
doi: 10.7498/aps.30.722
Abstract +
The Poincaré group is adapted as the gravitational gauge group. The equation of gravitational field in the Reimann-Cartan space-time with a Lagrangian containing linear and quadratic terms of strengths is investigated. For static and spherically symmetric field the vacuum solution in the macroscopic limit is shown to correspond to Schwar-zchild solution. Therefore this is in agreement with the experiments for general relativity. But in the microscopic limit, the field equation may predict a new type of short-range interaction.The spin 1/2 particle, Dirac particle, is taken as a probing particle. Its motion in the vacuum static and spherically symmetric gravitation field is explored. As a result, it is shown that the equation of motion of the Dirac particle only depends upon the Reimannian part of affine connection and has the same form as the corresponding equation of general relativity.
1981, 30 (6): 731-746.
doi: 10.7498/aps.30.731
Abstract +
We give a rigorous proof on the isomorphism between gauge groups before and after renormalization, in the presence of Abel subgroups and Higgs fields.
1981, 30 (6): 747-760.
doi: 10.7498/aps.30.747
Abstract +
The statistical theory of Type I antiferromagnetism of Ising spin 1/2 with the nearest neighbor interaction-J on a face centered cubic lattice has been treated by the method of series expansion. The degeneracy of the ground state is eliminated by introducing a next nearest neighbor interaction ～0+. The free energy function for the lower temperature ordered state is written in a series of exp(-4J/kT) and that for the higher temperature disorder state in a series of tanh (J/kT). Using Pade approximants, we have shown that the free energy curves of the two states cross at Tc = 1.74J/k, which clearly indicates the transition is of the first-order. The related physical quantities such as the long- and short-range order parameter, the internal energy, the entropy, the specific heat as well as the magnetic susceptibility were calculated following the variation of temperature. They all change abruptly at Tc and the latent heat Q = Tc△S = 0.44J. It is-proved that the theory of AB alloy superlattice, typically such as CuAul, may be for-mulated with its free energy similar to that of type I antife rromagnetism. Consequently, the characteristics of the transition and the physical quantities obtained can be naturally applied to the superlattice problem. We have shown analytically that the Tc- H curve exhibits a maximum at H=0.
1981, 30 (6): 761-774.
doi: 10.7498/aps.30.761
Abstract +
Using Green functions in an infinite medium, the constraint stress field of an inclusion with general shape is given. The stress free strains of the inclusion may be functions of position. On this basis, all calculating formulas for plane problems are given. We consider cracks or holes as special inhomogeneities with elastic constants equal to zero. For a body stressed by the applied field, the stress-free strains of the equivalent inclusion have been calculated. For oblate inclusions, near the end of major axis of ellipse, the stress field exhibits a r-1/2 stress singularity similar to that of a crack. Some applications, including the interaction of a hole with the applied field, micro-crack nucleation due to martensite plates and deformation twins, are discussed.
1981, 30 (6): 775-782.
doi: 10.7498/aps.30.775
Abstract +
It is pointed out in this paper that so far G-L theory for the critical magnetic field of superconducting thin films has not been verified by experiments although G-L theory has been extensively used to describe the critical magnetic field of superconducting thin films in the past three decades and it is the only theory to describe the critical magnetic field of strong-eoupling superconducting thin films. We find that the critical magnetic field of weak-coupling superconducting crystalline thin films can't be described by G-L theory and that the critical magnetic field of strong-coupling superconducting thin films can't be adapted also.In this paper, we present a new local criterion, i.e.ξ≤λ,ξ≤d would be satisfied simultaneously in the thin film limit. By means of this new local Criterion, we can explain disagreement between theories and theory and experiments.
1981, 30 (6): 783-793.
doi: 10.7498/aps.30.783
Abstract +
In the case of μ* = 0, the following Tc formula is derived analytically from the Eliashberg equation Tc=αωlogexp{-b((1+cλ)/λ)}, where, α = 2γ/π, b = c =1 and In γ = C = 0.5772 which is the Euler constant.The formula obtained by the authors holds only when Tc is less than 0.36/ α (K), where a is a constant larger than 1 and differs from one material to another. We conjecture, it is very likely that, when Tc is larger than 0.36/a, the functional structure of the Tc formula differs from that of McMillan's or at least the parameters a, b, and c are no longer constants independent of materials.
1981, 30 (6): 794-801.
doi: 10.7498/aps.30.794
Abstract +
In this article, a double heterojunction double drift-region InP/InGaAsP/InP avalanche diode is proposed. The analysis manifests: the voltage madulation depth is 100% corresponding to efficiency of 64%. The small signal theory analysis of the device impedance is also given.
1981, 30 (6): 802-809.
doi: 10.7498/aps.30.802
Abstract +
The general solution of TEM00-thermo-insensitive cavity in the presence of several thermo-perturbation centers has been obtained by means of the transformation circle diagram. In this cavity the circles π in the places of thermo-perturbation centers are tangent successively; one of the circles π1 is tangent to the circle σ1 of the mirror R1 of the cavity; and the spot sizes of the fundamental mode determined by the circles π satisfy the requirement selecting fundamental mode by self-diaphragm. At the same time, the simple designing process and calculating formulas of such cavity, particularly a frequency doubled cavity, has been established according to this solution.
1981, 30 (6): 810-819.
doi: 10.7498/aps.30.810
Abstract +
A new liquid crystal hybrid bistable optical device (BOD) is introduced. The optical bistability of two modes of operation of this LC BOD have been observed. The use of LC BODs for optical logic elements and ultralinear modulation applications is described. The transient response of LC BODs has been studied and a "critical slowing down" phenomenon has been observed. The switch time has been measured. The experimental results are in agreement with Garmire's theory.
1981, 30 (6): 820-826.
doi: 10.7498/aps.30.820
Abstract +
By means of tuning with a compound cavity, the output power of a pulsed dye laser can be increased several times and the output intensity be made almost independent of the frequency. The theory and experimental results are given as well as an example of a practical experimental device.
BRIEF REPORT
1981, 30 (6): 827-831.
doi: 10.7498/aps.30.827
Abstract +
In this paper, we describe the instrumentation and technique which are suitable for measuring first-Order instability threshold values of microwave field for both configurations of perpendicular and parallel pumping in magnetic order materials. The spin wave linewidth is derived from instability threshold values for parallel pumping. Experimental results are given for a sphere of yttrium iron garnet at room temperature and x-band. These results are in good agreement with those obtained by other researchers.
1981, 30 (6): 832-834.
doi: 10.7498/aps.30.832
Abstract +
We have investigated the influence of lattice defects caused by ion implantation on the line shapes of M?ssbauer spectra.
1981, 30 (6): 835-840.
doi: 10.7498/aps.30.835
Abstract +
Pressure dependence of the average rate of β→α transition of LiIO3 at different temperature was measured up to 12 kbars. With increasing pressure, the average rate of transition first increased sharply, then passed a maximum after that the transition rate would decrease in a comparatively gradual manner. Brief discussion on the pressure effect was also given.
1981, 30 (6): 841-848.
doi: 10.7498/aps.30.841
Abstract +
A technique of color restoration for faded color films with whitelight optical processing is presented. The color restoration can be accomplished with spatial encoding and color filtering. Although the technique offers an advantage of faded color encoding, however, it is not a real-time technique. We have also presented a real-time color restoration with white-light optical processing technique. Experimental demonstrations of this color restoration technique are also included. We have shown that the white-light color restoration is a simple, versatile and economical technique. The white-light processing technique also offers the advantage of direct viewing capability, which is very suitable for instantaneous color restoration and enhancement applications.
1981, 30 (6): 849-852.
doi: 10.7498/aps.30.849
Abstract +
This work investigates the high temperature decomposition process of theε-phase obtained by means of splat quenching in the Fe-C-Sb alloy by using differential thermal analysis, quenching sample X-ray diffraction analysis and powder photography employing Guinier-Lenne transmission high temperature monochromatic focusing camera. The results indicate that the ε-phase begins to decompose at 125℃. At first, it decomposes into ε-Fe2C, then α-Fe, Sb and Fe3Sb2 appear at 450℃, but ε-Fe2 Cremains at that temperature. Above 550℃, the ε-Fe2C phase transforms into Fe3C. The transformation of the α-Fe→γ-Fe was found to be at 770℃, and at 800℃ the main phases are:γ-Fe, Sb and Fe3C. The transformation of the γ-Fe→α-Fe was found to take place at 750℃during the cooling. The main phases at room temperature are:α -Fe, Fe3C, Sb and Fe3Sb2.
1981, 30 (6): 853-856.
doi: 10.7498/aps.30.853
Abstract +
We applied the heavy atom method to obtain the light atom positions of multi-solution type in the case of heavy atoms possessing a pseudo-symmetry whiCh is higher than that of the who'e structure. We introduced a model of pseudo-structure, derived an expression of diffraction structure factor FM(H) for a pseudo-structure and gave an estimate of correction term |EP(H)|.When we apply the heavy atom method of multi-solution type to a known structure, a perfect pseudo-structure pattern in obtained.
