Vol. 39, No. 11 (1990)
1990-06-05
GENERAL
1990, 39 (11): 1697-1704.
doi: 10.7498/aps.39.1697
Abstract +
The thermodynamic properties for a gas of one-dimensional fermi particles interacting via a repulsive delta-function potential have been studied under the limit of infinite repulsive coupling using the theory of grand canonical ensemble. All the thermodynamic functions have been found explicitly and the velocity of sound is derived as a function of the fugacity. In particular, the entropy is not zero at the absolute zero temperature for this model. Finally, some results are given for the arbitrary spin gas.
1990, 39 (11): 1705-1713.
doi: 10.7498/aps.39.1705
Abstract +
In this paper, we investigate the behaviour of the chaotic motions when parameter k>1 and k》1 for the circle map. We give out the measures of the chaos and it's scaling laws, by the methods of calculating the Lyaponov exponents and winding number for isometric point on Ω axis.
CLASSICAL AREA OF PHENOMENOLOGY
1990, 39 (11): 1714-1720.
doi: 10.7498/aps.39.1714
Abstract +
In this paper, the multi-photon field squeezing effects for the mixed absorptive-dispersive driven optical system in good cavity case is discussed. Under certain condition, for the single-photon case the squeezing effect of A1, one of the quadrature component of field, in the mixed systems is better than that in the pure absorptive systems. And for the two-photon case, the squeezing effect of A2, another quadrature component of field, may appear.
1990, 39 (11): 1721-1729.
doi: 10.7498/aps.39.1721
Abstract +
In this paper interaction of two-level atoms initially occupied the upper most level with a single mode of cavity field initially in a coherent state is investigated. Let the atoms interact in sequence with the field in equal time intervals and we find that the field can be kept in squeezed states and squeezed continuously in this process if initial intensity of the field is strong. The atoms interacting with the squeezed light are also discussed.
1990, 39 (11): 1730-1738.
doi: 10.7498/aps.39.1730
Abstract +
The fundamental equations describing the coherent light injection locking in semiconductor lasers are derived from semi-classical theory, the multi-branch structure and its stability, the steady modulation characteristic and its stability, several kinds of instability phenomena inside and outside the locking region and their distribution in the parametric plane representing the light injection condition are investigated. It is found that the stability region can only exist near the lower boundary and the right side in the locking region of the highest branch, and a self-pulsation region exists near to it. In the central portion in the rest part of the locking region there exists a chaotic region, between self-pulsation and chaotic regions is the transition region. In this transition region and outside the locking region there are bifurcation of self pulsation of 2p type and non-2p type, beat frequency self-modulation, and their mixed forms, the intermitant relaxation oscilation and intermiting chaos, etc., and several new routes to chaos.
1990, 39 (11): 1739-1744.
doi: 10.7498/aps.39.1739
Abstract +
The effect of the dispersive relation is investigated theoretically and a nominal linewidth broadening enhancement factor αe and an F factor related to the dispersive relation are introduced to modify the spectral linewidth formula of semiconductor lasers. It is found that the spectral linewidth not only can be suppressed by decreasing the linewidth broadening en-hancement factor, but also can be suppressed further by increasing the F factor. The mechanisms of the mode selection and linewidth compression in longitudinally coupled cavity (C3) are analyzed by means of the proposed effective reflectivity method, and the optimum condition for realizing single longitudinal mode with narrow linewidth is noted.
1990, 39 (11): 1745-1750.
doi: 10.7498/aps.39.1745
Abstract +
In this paper the motion of the electrons in a free-electron laser with untapered wiggler is discussed. We find the possibility of stochastic behavior for some traped electrons with the increase of the plasma frequency of the electron beam, when the energy exchange between the electron beam and the laser fields is taken into account.
1990, 39 (11): 1751-1757.
doi: 10.7498/aps.39.1751
Abstract +
The X-ray laser investigations in Ne-Like Ge were carried out using Shengguang (1012W) laser facility. An 1 m packaged grazing incidence grating spectrograph was positioned to view the plasma axially. The gain coefficients and the beam patterns were obtained from lasing line spectra. The measured gain coefficients of 19.638, 23.224, 23.627, 24.743 and 28.643 nm lasing lines were 3.06, 3.99, 3.72, 2.36 and 4.59 cm-1 respectively, the diverence angles of X-ray laser beams were about 12 mrad, the angles of X-ray laser beams from the axis of the line focus plasma were about 5.7 mrad.
1990, 39 (11): 1758-1763.
doi: 10.7498/aps.39.1758
Abstract +
In an annular resonator parametrically driven in the vertical direction, the irrotational movement of an incompressible fluid has been studied by the multiple-scales approach. The calculations have shown that under the condition that the radius of the annular resonator is much larger than the width the displacement of the movement of fluid surface satisfies the cubic Schrodinger equation. A non-propagating surface-wave solitons solution is obtained that describes the standing solitary wave observed by Wu, Keolian and Rudnick (1984).
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1990, 39 (11): 1764-1771.
doi: 10.7498/aps.39.1764
Abstract +
The propagation property of ion-acoustic soliton in a weakly inhomogeneous plasma caused by ionization is studied. Finite ion temperature and ion-neutral collisions are considered the self consistent, stationary distribution N(x), V(x) and the corresponding soliton solution are obtained, numerical results of soliton amplitude, speed and width dependent on position are given, which are reasonable and consistent with experiments.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1990, 39 (11): 1772-1777.
doi: 10.7498/aps.39.1772
Abstract +
In this paper, we report the amorphization observed in Fe-Ti and Fe-Si systems through a solid state reaction at low temperatures, and confirm the formation of amorphous Ni-Ti alloy after reaction. This new amorphization processes can be considered as the result from competing amorphous phase with crystalline phase in kinetics. A kinetical criterion for forming amorphous phase by solid state reaction is discussed in detail.
1990, 39 (11): 1778-1784.
doi: 10.7498/aps.39.1778
Abstract +
The optical-phonon deformation potentials (ODP's) of the tranary compounds Ga1-xAlxAs have been calculated by LMTO-ASA band structure technique combining with a virtual crystal approximation and a frozen-phonon model. The ODP's as a function of the Al composition x has been predicted. We find that the ODP's d0,d30,d10(val)and d10(cond) can be expressed as a quadratic equation of the compositions. Among them a small bending parameter is only connected with the d0 vs x, showing it to be a nearly linear dependence. The computational results also show that the d10(val) will equal to the d10(cond) at x≈0.65. So the ratio d30/d10 should be divergent at that composition. This fact implies that the contribution of the two-band term to the Raman tensor of the first-order resonance Raman scattering for energy gap E1-E1+△1 can be neglected at that composition in Ga1-xAlxAs. The reliability of our calculation results has been verified by using the relationship between the ODP's.
1990, 39 (11): 1785-1790.
doi: 10.7498/aps.39.1785
Abstract +
In this paper, a new method applied to some ionic conductors for measuring fundamental parameters of ionic conduction was developed based on the phenomena of light diffraction produced by a laser beam through these ionic conductors under a low frequency AC field. The ionic conduction parameters of aaaa-LiIO3 single crystal was measured by this method. The results are as follows. The activation energy of mobility Eμ=0.36eV. The formation energy of Frenkel defect EM =0.59 eV. At 300K, both the number densities of positive and negative carriers are 1.6×1017cm-3; their relative concentrations are 1.07×10-5; the effective mobility μeff+=3.9×10-8cm2·s-1·V-1 as the DC field applied to the crystal is antiparallel to its spontaneous polarization (we denote the voltage as V+) the effective mobility μeff- = 3.4 ×10-9cm2·s-1·V-1 as they are parallel (we denote the voltage as V-). Under the action of an AC field, in the half period that is corresponding to V+, it at least need that the ion hops 7 steps to form a space grating, and in another half period ion at least hops 32 steps to cause an oscillating component in the diffraction light intensity.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1990, 39 (11): 1791-1795.
doi: 10.7498/aps.39.1791
Abstract +
In the experimental study on electro-optical non linearity of crystal BSO, we observed that this crystal exhibits an optical isodensily performance when an external voltage is applied. In this paper the physical mechanism of this behavior is considered on the base of optical non-linearity of photorefractive crystal, and the experimental data, as well as the experimental results of several images, are given.
STUDIES AND ANALYSIS FOR MICROSTRUCTURES OF MICRO-CRYSTALLIZATION PROCESS OF AMORPHOUS SILICON FILMS
1990, 39 (11): 1796-1802.
doi: 10.7498/aps.39.1796
Abstract +
We have studied the fine procedure and characters of the microstructures for the a-Si:H and a-Si films, which have been changed from amorphous phase to microcrystalline phase, by means of Rigaku 3015 type X-ray diffraction spectroscope and high resolution electronic microscopy (HREM). This research provides some intuitive information for the transformation process, in which amorphous silicon filims change over from amorphous phase to micro-crystalline phase, and further deepens the understanding for the microstructures of amorphous silicon films.
1990, 39 (11): 1803-1810.
doi: 10.7498/aps.39.1803
Abstract +
In this paper, we report the study of the dependence of electrical resistivities of sputtering Pd films on their thicknesses and electrical resistivities of sputtering Pd films under different sputtering power. The results show that there is a small diversity between the latter theory of "size effects" and results of the thickness dependence of electrical resistivity. This diversity is due to effect of temperatures of the substrates. It shows that there is optimization during depositing on glass, and sputtering power would af fecth the electrical resistivity. After discussing the problem of substrate temperatures, we obtained a quantitative formula for the substrate temperature dependence of electrical resistivity.
1990, 39 (11): 1811-1814.
doi: 10.7498/aps.39.1811
Abstract +
Strong signal of fluctuation superconductivity has been found in RBa2Cu3O7-δ(R = Y, Gd) superconducting thin films near Tc through careful investigation on resistance transitions. Detailed analyses show that, for both polycrystalline and epitaxial YBa2Cu3O7-δ thin films, it tends to be of 2D characteristic when T》Tc, but a crossover from 2D to 3D will occur when T approaches Tc, which is consistent with the prediction of Lawrence-Doniach theory. The 3D-2D crossover can also take place when a rather weak field (1.5G) is applied parallel to Cu-O planes, but it is not the case when H is perpendicular to Cu-O planes, this indicates that there is a weak coupling between Cu-O planes in YBa2Cu3O7-δ. The same study on a GdBa2Cu3O7-δ epitaxial thin films shows that the 2D feature also appeares when T》Tc, but no evidence of 3D has been found when T approaches Tc, this we think is related to the self-moment of Gd ions.
1990, 39 (11): 1815-1819.
doi: 10.7498/aps.39.1815
Abstract +
Mossbauer measurements of YBa2Cu3-xSnxO7-y compounds with high Sn concentrations have revealed that the Sn dopants all exist as Sn4+, with their majority occupying Ba, Y, Cu(2) sites, and only a small part at Cu(l) sites. The amount of Sn at each site varies with Sn content (x). As for superconductivity, the sample systems are all with Tc above 77 K, this indicates that the substitutions for the metal ions on Cu(2) and Y sites have small effect on Tc, which strongly supports the concept that Cu-O plane does not predominate the superconductivity.
1990, 39 (11): 1820-1825.
doi: 10.7498/aps.39.1820
Abstract +
The effects of heat treatment on the hard magnetic properties and phase components are studied for amorphous Nd4Fe96-xBx alloys prepared by melt quenching technique. The crystallization temperature of amorphous Nd4Fe96-xBx alloys is higher than that of amorphous Fe100-xBx alloys at same B content in the range of 120-190 K. For 15≤x≤25, the samples crystallized from amorphous exhibit the hard magnetic properties, and consist of Nd2Fe14B, Fe3B and α-Fe. It is found that the intrinsic coercivity and magnetic energy product of the samples at optima1 heat treatment show a maximum of 2.8 kOe and 12 MGOe for Nd4Fe77B19 (x=19) alloy annealed at 670℃ for 2 min, respectively. These materials would presumably be used as an inexpensive bonded magnets, due to its higher values of Br and (BH)max.
1990, 39 (11): 1826-1829.
doi: 10.7498/aps.39.1826
Abstract +
From the analysing of the relaxation curves of magnetic annealing induced anisotropy of three cobalt based metal glasses, a linear relationship between the width of lognormal distribution of relaxation times (β) and the reciprocal temperature (1/T) has been established. This result implies that, in the process of relaxation, both Inτ0 and activation energy E obey the Gaussian distribution. The width of distribution for Inτ0 and E have been estimated.
1990, 39 (11): 1830-1834.
doi: 10.7498/aps.39.1830
Abstract +
The influence of metal optical property on the polarization effect in measurements of thin wire diameter with high accuracy has been studied in the present paper. The experimental Values of thin wire diameter obtained from its Fraunhofer diffraction patterns, which are produced by polarized light with the vibrations parallel and perpendicular to the wire axis respectively, is different. The theoretical analysis shows that this difference of wire diameter is approximately proportional to the imaginary part of complex index of metal, and is inde-pent of its real part. Some experimental results agree well with the theory.
1990, 39 (11): 1835-1841.
doi: 10.7498/aps.39.1835
Abstract +
Using a DV-X2 method of calculating the crystal-field spectra of transition-metal complexes in [1] , we calculated all the crystal-field transition energies of ruby non-empirecally. The results obtained are in good agreement with the experimental data.
1990, 39 (11): 1842-1847.
doi: 10.7498/aps.39.1842
Abstract +
In this paper, the M?ssbauer spectra of a-Fe90-xCoxZr10(x = 0,4,10,20) and Fe90-yCryZr10(y= 4,7,13,16) alloys were studied at 77K. The results indicate that two different magnetic states exist in a-Fe-(Co, Cr)-Zr alloys, the dependence of hyperfine parameters on the average outer electron concentration a of the 3d TM atom show anomalies in the vicinity of a = 8, which implies the invar effect of a-Fe90Zr10 and a-Fe-(Co, Cr)-Zr with low Ca(Cr). The reduced temperature dependence of the reduced hyperfine field reveal the existence of amorphous ferromagnetism in a-Fe90-xCoxZr10(x = 10, 20) and the spin-grass-like behavior in a-Fe90-xCoxZr10(x = 0,4). A new magnetic structure model are suggested and discussed.
1990, 39 (11): 1848-1853.
doi: 10.7498/aps.39.1848
Abstract +
We make use of the selectivity of pulse excitation in the central transition of spin-3/2 quadrupolar nuclei, and in powder sample, employ a 90°pulse to rotate the nuclear spin magnetization of certain spatial orientation of the electric-field-gradient tensor to the XY plane of the rotating frame for detection. Thus, high resolution spectrum similar to that obtained in a single crystal is acquired. The result is analyzed by density operator formula theoretically and confirmed by 23Na spectra of NaNO2 and Na2SO4 powders experimentally.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
1990, 39 (11): 1854-1862.
doi: 10.7498/aps.39.1854
Abstract +
A universal coordinate transformation leading to Hawking effect is obtained from only a few conditions whose physical meaning is clear. It is pointed out that the separation of the time variable and the space variable in the coordinate transformation is a sufficient condition for introducing the thermal effect when the new space-time is stationary and time-orthogonal. It is inferred that the "separation" in the coordinate transformation may be regarded as a new representation of the fundamental postulate upon which statistical mechanics is built.
