Search

Article

x

Vol. 30, No. 3 (1981)

1981-02-05
CONTENT
MEASUREMENT OF ALL COMPONENTS OF THE ELECTRO-ELASTIC TENSOR FOR α-LiIO3 CRYSTAL
LIU HONG-JU, ZHAO ZHE-YING, SHI ZHONG-JIAN
1981, 30 (3): 297-305. doi: 10.7498/aps.30.297
Abstract +
The persent work discusses the method of measuring the all components of the electro-elastic tensor for the α-LiIO3 crystal (LI). By means of theory of the thickness vibrational mode for piezoelectric plates, calculating formula of independent electro-elastic constants for LI had been developed. We measured the nonpiezoelectric-coupled elastic constants c11E and c66E by method of measuring velocity with acousto-optic synchronism, Finally, the 52 data of all components of the electro-elastic tensor and some of the electromechanical coupling factors for LI are given.
SIMULTANEOUS DETERMINATION OF Ku AND K1 OF THIN FILMS BY FERROMAGNETIC RESONANCE
LI JING-YUAN, ZHENG DE-JUAN
1981, 30 (3): 306-314. doi: 10.7498/aps.30.306
Abstract +
A formula for the resonance field along an arbitrary direction in a film of a cubic crystal, which possesses magnetocrystalline anisotropy (K1) as well as an uniaxial anisotropy (Ku) with the easy axis normal to the film plane, has been derived.On the basis of this formula, a method for the simultaneous measurement of (Ku) and (K1) is proposed. An example for an (111) film is considered specifically.
TRAVERSE TRANSPORT COEFFICIENTS OF PLASMA IN HOMOGENEOUS STRONG MAGNETIC FIELD
HU XI-WEI, HUO YU-PING, CHEN ZHENG-XONG, ZHANG CHENG
1981, 30 (3): 315-324. doi: 10.7498/aps.30.315
Abstract +
The traverse transport coefficients of plasma in strong magnetic field have been calculated by Kubo formulas and Landau representation. They are diffusivity, thermal-conductivity and viscosity. The method used in this paper is better than the general one of solving Boltzmann equation.1) The system, which is in strong magnetic field and subjects to multibody interaction, can be calculated without difficulty in principle. 2) It's physical model is simple and clear. 3) The analytic expressions of traverse transport coefficients can be obtained by calculating the matrix trace. Finally, we give a comparison between our results and general results obtained from Chapman-Enskog method.
A PROPOSAL OF FREEZING TOROIDAL MAGNETIC FIELD WITH THE SECTIONS OF SUPERCONDUCTING HOLLOWED CYLLINDER IN TOKAMAK APPARATUS
ZHANG YU-HENG, CAO XIAO-WEN
1981, 30 (3): 325-332. doi: 10.7498/aps.30.325
Abstract +
In the paper, we suggest a proposal that if n sections of the superconducting hollowed cyllinder which has been longitudinally cut are put into n longitudinal field coils for Tokamak apparatus, electric power of longitudinal field coils can be reduced to 2/n by sectional freezing of toroidal field,It is well known that freezing field Hfj of Superconducting material may be expressed approximately by the following equation: Hfj(r,T)=/Hfj(r, 0)[1-(T/Tc)2] Consequently, if we select that T = T1, the critical field will be reached at the internal wall of the superconducting hollowed cyllinder and magnetic field will go into it when the magnetic field reaches Hin≥ Hfj(r,T1). Then the magnetic field H will decrease to zero and the temperature will also decease to T2 which is far below the temperature T1. Thus this hollowed cyllinder can't be effected when magnetic field is being freezed in the neighbonring superconducting hollow cyllinder.Since electric power required is decreased by 2/n times, the power supply of middle sized apparetus operating at present is sufficient to provide power reactor.Since superconducting hollowed cyllinders with freezed magnetic field Hfj(r, T1) are put at temperature T2, after plasma is built it also can well equilibrate and stabilize plasma together with equilibrating field and feed backing field. Not only the role of Copper shells for equilibrating and stabizing plasma may be largely expanded by the combination of sections of the superconducting hollow cyllinder and copper shells with toroidal cuts in the internal wall, but also the thickness of copper shell can be decreased.Although electric power required for freezing toroidal field is greater than the power required by superconducting solenoidal magnet, however the local rise of temperature caused by the small mechanical movement of conductor due to the much large electromagnetic force in the superconducting magnet can be avoided.
THE AMBIPOLAR ELECTRIC FIELD AND THE AMBIPOLAR DIFFUSION IN A STOCHASTIC MAGNETIC FIELD
ZHANG CHENG-FU, WU WEI-MIN
1981, 30 (3): 333-343. doi: 10.7498/aps.30.333
Abstract +
It is shown that the transport of the plasma immersed in a stochastic magnetic field (s.m.f.) must lead to the producing of an ambipolar electric field. In this paper, the transition probability of charged particels in the s.m.f. was derived in the case of existing a transverse electric field. The transport fluxes and the ambipolar electric field were then calculated. The result shows that the ambipolar electric field is insensitive to the collision between particles. ((|e|E)/Te=-A1/ne(dne)/(dx), A is a coefficient ofabout 1, which depends on collision insensitively.) This ambipolar electric field may be used as a necessary (but not sufficient) criterion of ascertaining whether the effect of s.m.f. on the plasma transport is important. In the transport process induced by s.m.f. the impure ions transport more rapidly than hydrogen ions (VI/Vi≈[mi/mI]1/2ZI>1), this result can be used to explain the phenomenon in Tokamak experiment, i.e., when there appears interior disruption, the impurities will be extracted from centre region instead of being cumulated. We discussed also the effect of collision and the condition under which the above treat-ment is applicable. In the case of high collision, the diffusion flux is a much smaller quantity. The corresponding dynamic equation of plasma in a s.m.f. has been derived, it is somewhat different from that obtained by K. Molvig et al. in [3].
A NEW METHOD OF SOLVING THE TAKAGI EQUATION OF THE DYNAMICAL THEORY OF X-RAY DIFFRACTION
SUN ZHANG-DE, LIANG JING-GUO
1981, 30 (3): 344-350. doi: 10.7498/aps.30.344
Abstract +
The Takagi equation of the dynamical theory of X-ray diffraction is solved by the method of characteristic curve. The expressions of the strict and approximate solution have been derived. The meaning of Borrmann triangle is explained by the solution. To the first order, this expression of approximate solution is simple and explicit and coincides with known theory and basic experiments.
THE EFFECT OF LONG RANGE INTERACTION ON CRYSTAL GROWTH——MONTE-CARLO SIMULATION
ZHENG ZHAO-BO, HU ZHI-PU
1981, 30 (3): 351-360. doi: 10.7498/aps.30.351
Abstract +
In this article, the general expressions of kinetic rate constants under different conditions have been derived, with the long range interaction between molecules or between ions being considered. The interface configuration and the growth rate under different conditions have been simulated by using Monte-Carlo simulation method. The results show that, even in the case of molecular crystals in which only Van de Waals forceacts, the long range interaction still cannot be ignored; as in AB type ionic crystals, the long range interaction must be taken into account. In order to surmount the difficulty of Calculating long range interaction, we adopt the neutral combination method.
THE ROLE OF QUENCHED-IN VACANCIES IN THE ORDERING PROCESS OF AuCu ALLOY
SHI TIAN-SHENG
1981, 30 (3): 361-368. doi: 10.7498/aps.30.361
Abstract +
The effect of quenching and aging temperature on ordering process of AuCu alloy was investigated.Based on the experimental results obtained, we concluded that1. The ordering process of AuCu alloy can be divided into two stages: 1) formation of short-range order or nucleation with increase in resistivity, followed by 2) long-range ordering with decrease in resistivity.2. The ordering kinetics of AuCu alloy during low temperature aging is mainly limited by migration of the quenched-in vacancies. The rate of ordering process is proportional to the concentration and mobility of quenched-in vacancies.3. The formation energy and migration energy of vacancies in AuCu were estimated to be 0.95 eV and 0.81 eV respectively.4. During isothermal aging, the quenched-in vacancies in AuCu decayed according to the law of second-order reaction.
THE EXTENSION OF THE NEW GRAPHIC METHOD FOR INDEXING DEBYE-SCHERRER PHOTOGRAPHS TO ORTHORHOMBIC AND MONOCLINIC SYSTEMS
LU XUE-SHAN
1981, 30 (3): 369-382. doi: 10.7498/aps.30.369
Abstract +
The new graphic method of indexing Debye-Scherrer photographs has been extended to orthorhombic and monoclinic crystals. Line coordinates are amply utilized. Thus the condition that the solution of a series of Diophantine simultaneous linear equations is represented by the interception of a series of conditional lines is replaced by a series of conditional points that passes through a common straight line, the reciprocal intercepts of which on the coordinate axes represent the common solution.Only special cases have been considered. For the orthorhombic system, it is supposed that among the observed lines, there exists a series of reflexions belonging to(1)(hi,0,0),(0,ki,0),(0,0,li);(2)(hi,ki,0),(0,ki,li),(hi,0,li);(3)(hi,k,l), (h,ki,l),(h,k,li) or (4)(hi,ki,l),(h,ki,li),(hi,k,li). And for the monoclinic system, it is supposed that there exists a series of reflexions belonging to (l)(hi,0,0,0),(0,ki,0),(0, 0,li);(2) (hi,ki,0), (0,ki,li); (3) (h,ki,l); (4) (hi,k,l), (h,k,li) or (5) (hi,ki, li)(hi,ki,li),(hi,ki,li),(hi,ki,li). Here the index without a subscript indicates that it remains unchanged in the family of reflexions.A novel feature in this work is that the concept of quadratic difference △isn2θij = sin2θj-sin2θi has been introduced into the graphic method. Thus if there is a set of reflexions in the monoclinic system belonging to the family (hi, k, l), and if we plot (△h2ij/△sin2θij, l△hji/△sin2θij) as conditional points, and if there exists a straight line connecting three or more conditional points arising from different △sin2θij then the reciprocal intercepts of the straight line on the coordinate axes will give A2 and 2AC cosβ, where A=λ/2a sinβ and C=λ/2c sinβ.
STATISTICAL THEORY OF A ONE-DIMENSIONAL INTERACTIVE KINK-PHONON GAS
YANG ZHEN-QING
1981, 30 (3): 389-400. doi: 10.7498/aps.30.389
Abstract +
This paper systematically studies and improves the statistical theory of the kink-phonon interactive mixture in a one-dimensional model for the displacive phase transition. By taking applicable forms of the path integral for both the partition functions of kink and phonon and altering the method in calculating the path integral of phonon, a more reasonable and general expression of the partition function of the Grand ensemble is obtained. Under the lowest eigenstate approximation, the Grand.partition function may be reduced to a result similar to that of reference[6]. Under the classical approximation, the average density of the kink calculated from the Grand partition function is in agreement with the result of the computer simulation better than those obtained in earlier publications.
DETERMINATION OF PENTAACETYLSARMENTOSIN CRYSTAL STRUCTURE
ZHENG QI-TAI, GU YUAN-XIN, ZHENG CHAO-DE, QIAN JIN-ZI
1981, 30 (3): 393-388. doi: 10.7498/aps.30.393
Abstract +
Pentaacetylsarmentosin is a derivative of Sarmentosin which is one of effective component of plant Sedum sarmentosum Bunge. The molecular formula is C21H27O12N. Pentaacetylsarmentosin crystals belongs to the orthogonal system, space group D24P212121. The cell dimensions are a = 19.756(3)?, 6 = 17.013(3)?, c = 7.482(1)?; four molecules are contained in a cell (z = 4). Intensity data were collected on a PW-1100 four circle diffractometer.The original MULTAN-78 was not successful in solving the structure, the correct structure solution was obtained by optimal selection method used to improve the index distribution of starting reflection set.Refinement of the structure paramenters was acheived by block-matrix Least-squares (program XTL (1974)), R = 0.051 (sin θ/λ≤ 0.48), R = 0.063 (all observed reflections). All the positions of hydrogen atoms except the methyes were located by the difference syntheses.
TIME REVERSAL SYMMETRY AND NON-EQUILIBRIUM STATISTICAL STATIONARY STATES (II)
ZHOU GUANG-ZHAO, SU ZHAO-BIN
1981, 30 (3): 401-409. doi: 10.7498/aps.30.401
Abstract +
This is the 2nd part of our discussion on time reversal symmetry applied to the non-equilibrium statistical stationary states (NESS) from a microscopic quantum statistical point of view. With the application of the main results of I, a systematic investigation on the general properties of the NESS is given. For systems invariant under time reversal, the existence of a generalized potential and the fluctuation-dissipation theorem in the low frequency limit are established in the NESS. The Onsager's reciprocity relations for the local thermodynamical equilibrium systems are also generalized to that for the NESS invariant under time reversal symmetry. Finally, the time dependent 'Ginzburg-Landan equations for order parameters and conserved densities have been expressed in a general form with time irreversible and reversible parts similar to that met in the literatures studying critical dynamics.
BRIEF REPORT
ON THE AMPLITUDE-PHASE RETRIEVAL PROBLEM IN OPTICAL SYSTEMS
YANG GUO-ZHEN, GU BEN-YUAN
1981, 30 (3): 410-413. doi: 10.7498/aps.30.410
Abstract +
In this paper we propose a general description of the amplitude-phase retrieval problem. A set of equations for the determination of amplitude-phase based on rigorous mathematical derivation is established. Using these equations and the iteration computing method, a variety of reconstruction problems can be solved.
GENERAL THEORY ON PERFORMING OPTICAL TRANSFOR-MATION USING AMPLITUDE-PHASE MASKS
YANG GUO-ZHEN, GU BEN-YUAN
1981, 30 (3): 414-417. doi: 10.7498/aps.30.414
Abstract +
In this paper the previous theory on performing a given linear transform using the pure phase mask system[1,2] has been generalized to the more general case in which an optical system is composed of amplitude-phase masks. A set of equations which is necessarily satisfied by the amplitude and phase distributions of the masks is given. It is easy to solve them by means of the iteration computing method.
DETERMINATION OF 3, 4-METHYLENEDIOXY-BENZOYL PICOLINE CRYSTAL STRUCTURE
ZHENG QI-TAI, QIAN JIN-ZI, GU YUAN-XIN, ZHENG CHAO-DE
1981, 30 (3): 418-423. doi: 10.7498/aps.30.418
Abstract +
3, 4-METHYLBNEDIOXY-BENZOYL PICOLINE crystal belongs to mono-clinic system. The space group is C2k5-P21/c with four formula units in a cell of dimension a = 10.381(2)?, b = 7.163(2)?, c = 16.951(3)?, β = 107.51 (5)°. The structure was solved by direct method (MULTAN-74). Eefinement of structure parameters was acheived by BLOCK-matrix least-squares method, R = 0.072 (for 2176 observed reflexions) .The intensity data were collected on PW-1100 four-circle diffractometer.All of the hydrogen atoms were located in the difference Fourier maps. The molecules are bound by the van der waals' force.
THE OXIDIZING PROCESS OF Fe3O4 ULTRAFINE PARTICLES
DU YOU-WEI, ZHANG YU-CHANG, LU HUAI-XIAN
1981, 30 (3): 424-427. doi: 10.7498/aps.30.424
Abstract +
The conversion of magnetite to maghemite has been studied by M?ssbauer effect. That is a nucleation and growth process of γ-Fe2O3. The change of the concentration of Fe3O4 with time was determined by the change of magnetic moment in the oxidizing process. The chemical reaction formula, -dC/dt = mC3, is only appropriate for the starting stage of the oxidizing process.
THE MECHANISM OF THE GRAIN GROWTH OF SUPERCONDUCTING COMPOUND Nb3Sn
TANG XIAN-DE, WU ZI-QIN, GAO QIAO-JUN
1981, 30 (3): 428-432. doi: 10.7498/aps.30.428
Abstract +
Grain growth of the Nb3Sn at the Nb/solid Cu-Sn and Nb/liquid Cu-Sn interface has been investigated. Experiments have revealed that the grain growth of the Nb3Sn at the solid/solid interface still conforms to the ordinary law of the grain growth in metals, though the Nb3Sn grain size (~0.1 μm) is much smaller than that of the metals. The Nb3Sn layer growth at the solid/liquid interface is divided into two layers: (1) near the Nb, the grains are fine and closely packed, (2) near the liquid Cu-Sn, the grains are coarse and dispersive. The coarse grains, are thought to be formed by a solution/deposition process. Most of the Nb3Sn crystals have the appearance of rhombic dodecahedron and orthogonal parallelepiped. It is evident that the interfacial energy of the {110} and {100} planes of the Nb3Sn crystal is lower than the others.