Vol. 39, No. 4 (1990)
1990-02-20
GENERAL
1990, 39 (4): 511-517.
doi: 10.7498/aps.39.511
Abstract +
The algebra of meromorphic vector fields with multi-poles on Riemann sphere and the central extension of the algebra are constructed explicitly. Some properties of meromorphic λ- differentials, in particular, of the third kind differentials are investigated.
ATOMIC AND MOLECULAR PHYSICS
1990, 39 (4): 518-525.
doi: 10.7498/aps.39.518
Abstract +
The 23Πg-13∑u+ diffuse fluorescence spectrum around 5730? for K2 dimer excited by 4415.6? CW Isser line was obtained. The collision-induced enhancement effect of the maximum intensities Idiff of the diffuse spectrum versus the pressure P ot buffer gas Ar was studied experimentally. The energy transfer processes of C1Πu-23Πg was showed by stable collision model. The Idiff-P relation was deduced and a satisfactory fitting for the experimental data was obtained by use of this model. This fitting showed that the energy crossing rate and collision-induced transfer rate could be obtained by this model with some alternations of the experimental setup.
CLASSICAL AREA OF PHENOMENOLOGY
1990, 39 (4): 526-530.
doi: 10.7498/aps.39.526
Abstract +
Six pairs of Stokes-anti-Stokes lines of stimulated four photon mixing in a multimode fiber with GeO2+P2O5 doped silica core are simultaneously recorded. A continuum band generated jointly by SFPM and stimulated Raman scattering is obtained in the spectral range 540-640 nm. On the basis of two different experiment results for 20 m and 200 m fiber, the mechanism of competition and transformation between SFPM and SRS are analyzed in some detail.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1990, 39 (4): 531-540.
doi: 10.7498/aps.39.531
Abstract +
In this paper the principle, experimental setup and technique of the tokamak poloidal magnetic field measurement by laser excited fluorescence of high energy Li beam are presented. The main diffeculties and its limitations are also mentioned.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1990, 39 (4): 541-546.
doi: 10.7498/aps.39.541
Abstract +
The crystallization behaviour of Ni51Zr49 amorphous alloy has been studied by the transmission electron microscopy (TEM). It has been found that a metastable phase, NiZr, in rose-like morphology with C-centered monoclinic lattice, a = 0.3268, b = 0.4101, c = 0.5224nm and β= 71.8° in amorphous matrix in the earlier stage of the crystallization, The following orientation relationships between the metastable phase and the stable phase, NiZr, exist: [100]NiZr＇//[100]NiZr [001]NiZr＇//[ll0]NiZr. NiZr＇ phase is regarded as a metastable state of NiZr phase and transforms to NiZr phase gradually with an increase in temperature. A small quantity of Ni10Zr7 phase formed in the final stage of the crystallization. Both NiZr and NiZr＇ have complex twins with two principle typies, one of which is 180°twins with the [02l] direction of NiZr or NiZr＇ as axis and another 36°rotation twins with [001] of NiZr or [010] of NiZr＇ as axis. The total amount of twins decrease gradually with the increase in temperature.
1990, 39 (4): 547-554.
doi: 10.7498/aps.39.547
Abstract +
Based on our paper (I), we calculate the free energy of the hydrogen-bond ferroelectrics system with four-body interactions, and propose the conditions to determine the Curie temperature and the discontinuity of the first order phase transition. The detailed analysis of free energy around the transition temperature indicates that the results of our microscopic model coincide with the predictions of Landau's theory. And the relations between the coefficients in Landau free energy and the microscopic interaction constants are obtained, that makes the physical meaning of these coefficients more clear. By comparing with the experimental data of PbHPO4, PbDPO4 and H2C4O4 crystals, we confirm that our theory can successfully explain the first order ferroelectric phase transition as well as the second order transition.
1990, 39 (4): 555-560.
doi: 10.7498/aps.39.555
Abstract +
This paper reports the result of undercooling experiment of Pd-Ni-P alloy. Bulk metallic glass of Pd41)Ni40P19 has been formed by thermal treatment with B2O3 as fluxing. The effect of cooling rate on the undercooling behavior was studied. The surface heterogeneous nuclea-tion was reduced by embeding the sample into B2O3 melt. Thus the cooling rate used to form the glass was as low as 1 K/s at the glass transition temperature of 590 K. The temperature-time-transformation curves were calculated by using the classical homogeneous and heterogeneous nucleation theory. The critical cooling rates for the glass formation were calculated. The resuits are discussed in some detail.
1990, 39 (4): 561-564.
doi: 10.7498/aps.39.561
Abstract +
The X-ray diffraction (XRD) and scanning electron microscopy (SEM) study was carri-ed out for an amorphous Cu+ conductor 0.4CuI-0.3 Cu2O-0.3P2O5 with the simultaneous conductivity measurement in the isothermal heat treament process. The results indicated that the initial amorphous material was phase-separated. In the course of time, the separated amorphous phase disappeared, the crystalline γ-Cul and Gu2P2O7 formed in sequence and grew up gradually. The correlation of the phase separation and crystallization behavior with the con-ductiyity anomaly confirmed again the interface effect between different phases in amorphous fast ionic conductors and its universality.
1990, 39 (4): 565-571.
doi: 10.7498/aps.39.565
Abstract +
It is shown that Landau's mean field theory of Fermi liquids is valid in two-dimensional case through evaluation of the quasiparticle life-time of a 2-D interacting Fermi systems at low density as well as the spin fluctuation of 2-D itinerant Fermi systems.
1990, 39 (4): 572-579.
doi: 10.7498/aps.39.572
Abstract +
2-D liquid 3He is studied using the method of correlated basis functions (CBF). The cluster expansion technique is extended to treat finite temperature systems based on variational principle for the partition function. Adopting a Lennard-Jones potential, the ground state energy, quasi-particle energies and the Landau parameters are evaluated to the second order.
1990, 39 (4): 580-590.
doi: 10.7498/aps.39.580
Abstract +
We discuss transport properties and sound propagation of 2-D Fermi liquids. Microscopic expressions for the coefficients of diffusion, viscosity and thermal conductivity are derived using Resibois method. Velocities of the zeroth and first sounds are calculated. Based on an analysis of collision integral, it is shown that a series of relaxtion time parameters is necessary to define precisely the sound propagation properties in 2-D Fermi liquids, in contrast to the 3-D case.
1990, 39 (4): 591-598.
doi: 10.7498/aps.39.591
Abstract +
The discussion on the theoretical models for the wetting transition up to now shows that making the range of wall potential longer tends to favor first-order wetting transition. To this proposition, however, a counter-example treated analytically is presented in the present paper.
1990, 39 (4): 599-606.
doi: 10.7498/aps.39.599
Abstract +
The growth characteristics and surface reconstruction of Ge/Si(lll) and Si/Ge(lll) are studied by reflection high energy electron diffraction (RHEED) and Auger electron spectros-copy (AES). The growth modes are proposed based on the results. The stain effects on the growth characteristics, interface structure and surface reconstruction are further discussed.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1990, 39 (4): 607-613.
doi: 10.7498/aps.39.607
Abstract +
By using the electron correlated basis function of excited state, we calculate the effect of electron interaction on the bandwidth of conductive polymers. By taking into account the electron interaction, the bandwidth is apparently narrowed as compared with that obtaind with single-electron theory. The difference is -25.9%.
1990, 39 (4): 614-619.
doi: 10.7498/aps.39.614
Abstract +
Since the discovery of specific anomalous electromagnetic character of n-Ge above room temperature, the inversion layer model has been very successful in theoretical investigation of anomalous Hall effect. However, up to now this model has not been verified experimentally. This paper reports this aspect of work.
1990, 39 (4): 620-626.
doi: 10.7498/aps.39.620
Abstract +
For the second harmonic generation at metal suriaces, the existing theoretial results obtained from hydrodynamics and the density functional theory are one order of magnitude deviated from the experimental data. We calculate the second harmonic generation at Al, Mg and Ag surfaces by using the correlated basis function theory. Since the electron correlation can be considered more property in this approach, our theoretical results are closer to the experimental data.
1990, 39 (4): 627-631.
doi: 10.7498/aps.39.627
Abstract +
The influence of steady LED irradiation on the photocurrent spectra of the strained layer multiple quantum wells In0.15Ga0.85 As (8nm)-GaAs (15nm) with 15 periods have been studied from 10 K to 300 K. The photocurrent peaks corresponding to various transitions decrease in different ways with the increase of LED irradiation intensity. By this means, the transitions from confined subband to continuum can be identified easily, and the conduction- and valence-band edge discontinuity has been determined directly from the experimental energy values of various transitions. Consequently, the band offset of heavyhole valence band is obtained as Qv = 0.38±0.01.
1990, 39 (4): 632-638.
doi: 10.7498/aps.39.632
Abstract +
Starting from the quasiparticle and phonon kinetic equations and the order parameter equation, we have obtained a hydrodynamic equation for a superconductor and theor etically verified the possibility of unusual diffusion of quasiparticles from regions with lower concentration to regions with higher concentration as well as the stabilizing term for short-wave fluctuations.
1990, 39 (4): 639-648.
doi: 10.7498/aps.39.639
Abstract +
In this paper, we study the spin waves in transverse Ising ferromagnetic films by means of the Green function theory. The dependence of the spectrum and intensity of spin waves on the parameters related to the film is discussed in detail
1990, 39 (4): 649-655.
doi: 10.7498/aps.39.649
Abstract +
Nd2(Fe1-xMnx)14B crystallize in the tetragonal structure, space group P42/mnm, when xiHc shows a composition dependence. The form of the virgin magnetization curve is characterized by a propagate field Hp. The value of Hp is close to that of iHc, indicating that the intrinsic coercive force is created by domain wall pinning. The temperature dependence of iHc were studied. The strength of the pinning potential barrier was estimated. The Curie temperature and saturation magnetization of Nd2(Fe1-xMnx)14B were measured. The exchange interaction in the pseudoternary compounds decreases dramatically with substitution of Mn for Fe. That results in a decrease of the thickness of domain walls. The magnetization and demagnetization behaviors in Nd2(Fe1-xMnx)14B can be understood in terms of narrow domain walls.
1990, 39 (4): 656-660.
doi: 10.7498/aps.39.656
Abstract +
This paper studied the temperature dependence of saturation magnetostriction λ4 in both systems Fe80-xCuxSi5B15 and (Fe1-xCox)82Cu0.4Si4.4B13.2. The range of temperature is respectively from room temperature to the Curie temperature of amorphous state and to that of the crystal-line state. The structural changes following the temperature variation are analyzed, and the single-ion microscopic mechanism of magnetostriction is discussed.
1990, 39 (4): 661-666.
doi: 10.7498/aps.39.661
Abstract +
Samples with nominal composition Bi2-xPbxSr2Ca2Cu3Oy(x = 0.30;0.35;0.40;0.45) have been prepared by solid state reaction. Phase and structure analyses have been performed, and the resistance-temperature relation and dc susceptibility have also been measured. The results show that the sample with x = 0.35 is a single-phase material. X-ray analysis and electron differaction indicate that its phase structure is similar to that of 2223 phase, it is tetragonal with a = b = 5.414?, c = 37.106?, we observed also the modulated structure along a and b. The results of resistance-temperature and dc susceptibility measurement show that, when T = 50 K, there is only one superconducting phase of 107K. In addition, we find that the preparation condition of the single-phase material (composition, sintering temperature and the quenching rate) is stringent. Like the 1-2-3 phase material, the oxygen content not only influences the phase, zero-resistance temperature of the sample, but also influences the transport property of normal state.
1990, 39 (4): 667-671.
doi: 10.7498/aps.39.667
Abstract +
Positron annihiation, in situ observations of heating process by using 1000 kV HVTEM as well as magnetic measurements have been used to study the coercivity mechanism. The results show that Sm2Co17 precipitates themselves are not nucleation centres for the formation of reverse domains. It seems reasonable that some structural and compositional inhomogeneous regions have a fairly low magnetic anisotropy which may act as nucleation centres.Experiments show that the maximum irreversible loss appears at 750℃ during aging from 25℃ to 900℃ for SmCo5. The magnetic anisotropy of the central Sm3+ with different near neighbour Sm3+ ion distribution is not fixed. The more the structure simitar to Sm2Co17, the more probable that Sm3+ is negatively anisotropic.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1990, 39 (4): 672-676.
doi: 10.7498/aps.39.672
Abstract +
During final annealing of the grain-oriented 3%Si steel sheet, the secondary nuclei form in the subsurface layer of the sheet, but their growth modes depend on cold-rolling reduction. According to the growth characters of conventional and high permeability grain-oriented silicon steels, a quantitative relationship among the parameters, such as the diameter of primary grains, inclusion factor and critical size of secondary nuclei, is derived by the energy analysis. The calculated result is consistent with experimental data of previous works.
