Vol. 34, No. 5 (1985)
1985, 34 (5): 573-580. doi: 10.7498/aps.34.573
A new approach of the O-expansion of the Green's function is empoyed to study the time dependent problem of the Fokker-Planck equation. The scaling region and the final region in the scaling theory is unified to a single region. As t→∞ the time dependent solution approaches the stationary solution of the Fokker-Planck equation. The difficulty of matching the last two time regions in the scaling theory is then avoided.
1985, 34 (5): 581-587. doi: 10.7498/aps.34.581
Bifurcation and chaos behavior in liquid crystal hybrid optical bistable devices is calculated and analysed based on the relaxation equation with time-delayed feedback. We also find that there is a transient oscillation with period ta within the bistable region.
1985, 34 (5): 588-593. doi: 10.7498/aps.34.588
In curved space-time the γ-algebra is proved and the Barita-Schwinger equation is written out explicitly in the tangent space, On the bases of equivalent principle, the Rarita-Schwinger equation in curved space-time is obtained.
AN EXPERIMENT OF 90° THOMSON SCATTERING ON CT-6B TOKAMAK DEVICE BY USING A RUBY LASER AS LIGHT SOURCE
1985, 34 (5): 594-602. doi: 10.7498/aps.34.594
In this paper, we describe briefly the 90°Thomson scattering system of Tokamak CT-6B, using a ruby laser as light source. The measurements of the 90°Thomson scattering spectra, electron temperature Te and density ne, are discussed. The results are given. The result of electron density measurement agrees with that Obtained by 2 mm micro wave interferometer diagnosis.
THEORETICAL CALCULATION OF PULSED ACTIVE-PASSIVE MODE-LOCKED SOLID-STATE LASERS (Ⅰ)——THEOEETICAL MODEL
1985, 34 (5): 603-610. doi: 10.7498/aps.34.603
A theoretical model for pulsed active-passive mode-locked solid-state lasers is presented in this paper. The characteristics of these lasers can be solved by computer simulation with this model.
THEORETICAL CALCULATION OF PULSED ACTIVE-PASSIVE MODE-LOCKED SOLID-STATE LASERS (Ⅱ)——COMPUTER SIMULATION
1985, 34 (5): 611-621. doi: 10.7498/aps.34.611
Computer simulations are carried out with the theoretical model presented in the previous paper for pulsed active-passive mode-locked Nd-glass and Nd : YAG lasers. The dependences of some characters of active-passive mode-locked lasers, such as mode-locking threshold, output stability, pulse width, pulse asymmetry, on modulation depth and detuning of the active modulator, concentration and relaxation time of the satura-ble dye, are given by the simulation calculations. The theoretical results are qualitatively in good agreement with experiments. Some experimental observations are explained. Thereby the physical processes involved in active-passive mode-locking are understood more deeply.
POSITRON LIFETIME SPECTRA AND SCANNING ELECTRON MICROSCOPE INVESTIGATIONS DURING THE CRYSTAL-LIZATION PROCESS OF AMORPHOUS IONIC CONDUCTOR B2O3-0.7Li2O-0.7LiCl-xAl2O3
1985, 34 (5): 622-627. doi: 10.7498/aps.34.622
The traditional pressed powder-samples spoil seriously the accuracy and reproduci-bility in measurement of positron lifetime spectra and scanning electron microscopy. This paper has overcome the above difficulties by preparing large amorphous disk-samples, and obtained new result of positron lifetime spectra and scanning electron microscopy during the crystallization process.According to our experiements on amorphous ionic conductor B2O3-0.7Li2O-0.7LiCl-xA12O3, we find that the mean lifetime of positron at room temparature is not affected by content Nariation of A12O3, mean lifetime of positron decreases greatly after full crystallization. Moreover, during the beginning of the crystallization process mean lifetime of positron of sample of x=0.15 exhibits a notable anomalous enhancement, which occurs within the same temperature range while the anomalous enhancement of ionic conductivity appears.
1985, 34 (5): 628-633. doi: 10.7498/aps.34.628
The absolute thermoelectric power S of amorphous metallic alloys (Fe1-xCrx)84B16 has been measured as a function of temperature in the range of 80 to 380 K for 0.01≤x≤0.46. It is found that the behavior of S(T) for the magnetic alloys does not always follow a nonlinear variation law with a shallow minimum. The. addition of a small amount of Cr (x≤0.05) is shown to lower the absolute value of S and wash out the minimum. With a larger Cr content, the alloys are weakly magnetic and the behavior of S(T) changes from nonlinear, typical of magnetic amorphous alloys, to nearly linear, similar to that for nonmagnetic alloys. A value of x of 0.15 and 0.25 is not found to have any effect on the value of 8 at the Curie temperature Tc, which happened to he in our working temperature region.
1985, 34 (5): 634-639. doi: 10.7498/aps.34.634
The interface formation process for In deposited on noncleaved GaAs (111) plane has been studied by means of photoemission speetroscopy combined with LEED pattern analysis. It is shown that the growth of three-dimensional In clusters dominates in this process. The surface Fermi level is found at 0.75±0.05 eV above VBM for all the investigated n-type samples prior to the deposition of In: these include both Ga-terminated GaAs(lll)-A and Asterminated GaAs (lll)-B faces. The Fermi level rapidly shifts to 0.90±0.05 eV above VBM during the deposition of In.
THE MECHANISM OF CONDUCTIVITY AND THE SUPER-CONDUCTING TRANSITION ANOMALIES IN METASTABLE INTERMEDIATE PHASE
1985, 34 (5): 640-651. doi: 10.7498/aps.34.640
The relation between conductivity σ(Ta) and temperature T has been investigated experimentaly for the samples with different structure under phase transition. We have found anomalous phenomenon on superconducting transition R(T) curves corresponding to some special phase transition zones as the samples crystallize into metastable intermediat phase.In this paper, a mixed state model is suggested, in which the metastable metal-phase and the quasi-semiconducting phases are mixed. Based on this model, the anomalous phenomenon can be explained and the theoretical calculations is carried out. The theory is in agreement with experimental data fairly.
We choose the typical metallic glass Cu1-xTix alloys with two concent ations (x= 0.300 and x=0.325) made by melt-spinning technique as the sample. The X-ray diffraction, DTA and DSC analyses show that the samples exhibit typical amorphous charac-teristecs. In the wide temperature range 2-700 K, the resistivity is in aceordance with Mooij rule. Based on the Nagel nearly free electron model, Mott s-d scattering model, quasi-particles excitation by disorder configuration model and two-level tunnelling model for the electrical transport properties of amorphous alloys, the results are analysed,. The theoretical results in two level tunnelling model agree with the experimental data much better.
1985, 34 (5): 663-666. doi: 10.7498/aps.34.663
For SU(2) lattice gauge theory, three alternative forms of action proposed by us are studied by means of Monte Carlo method, their internal energy per plaquette and specific heat are calculated. The curves of their internal energy approach to the same weak-coupling approximation when β is large. There are peaks on their specific heat curves which indicate the critical points of transition from strong-coupling to weak-coupling. We find clear evidence showing that the deviation of critical point is only due to the difference of higher order terms of lattice spacing a.
1985, 34 (5): 667-673. doi: 10.7498/aps.34.667
We studied the dielectric and elastic properties of LiKSO4 crystal under various temperature (150-350 K) and pressure (0-10 kbar). An anomalous change of the dielectric and elastic constants was found near the room temperature and 8.2 kbar (correspond to raising pressure) and 4kbar (correspond to releasing pressure). We attribute this anomalous change to the phase transition induced by the pressure. The process of this phase transition is accompanied by large pressure hysteresis.We also obtained the p-T phase diagram of LiKSO4 in these temperature and pressure range. A triple point was found near 3.8 kbar and 281 K.
1985, 34 (5): 674-680. doi: 10.7498/aps.34.674
Single crystals of K5Bi0.9Nd0.1 (MoO4)4 and K5Bi0.97Nd0.03(MoO4)4 were grown from sto-ichiometric melts by the usual Czochralski technique. The crystal (Nd = 0.1) belongs to trigonal system, with space group R3m, Z = 1.5, and cell parameters a = 6.023 ?, c=20.887?.The room temperature absorption spectra of K,Bi(MoO4)4-Nd3+(3 % or 10 % Nd3+) consist of several bands characteristic of the rare earth Nd ions in crystals. The substitution of Nd3+ by Bi3+ does not affect the surrounding of the active ions. Details of room temperature emission spectra corresponding to the 4F3/2→4I13/2 and 4F3/2→4I11/2 transitions are also given.
1985, 34 (5): 681-684. doi: 10.7498/aps.34.681
The dendritical spaped precipitates in GH 302 alloy were identified as C14 type Laves phase by means of CBED, SED and X-ray mitro-analysis.
1985, 34 (5): 685-688. doi: 10.7498/aps.34.685
It has been shown that the paramagnetic ions doped in KMgF3 are in axial symme-try environment. In the present work, that the shift of the nearest neighbour F- ions of the K+ vacancy, 3.76°and -0.64°deviating from the c3 axis respectively, are predic-ted by analysing the anisotropic g factors and the zero-field splitting of EPR.
1985, 34 (5): 689-693. doi: 10.7498/aps.34.689
Inelastic neutron scattering spectra of LaNi4.5Mn0.5Hx (x=1.2, 4.2, 5.6) have been measured using berylium filter detector spectrometer. From the spectras, it was found that the second and the third peak of optical branches shifted 6 meV and 10 meV towarcs high frequency respectively, and the M-H bond in LaNi4.5Mn0.5Hx became stronger than that in LaNi5Hx, after the same part Ni of LaNi5 was replaced by Mn. Finally, we explained the cause of this phenomena in brief.
A MODEL OF QUASI-PARTICLE EXCITATION BY DISORDER CONFIGURATION FOR THE LOW TEMPERATURE ELECTRONIC RESISTIVITY IN METALLIC GLASS
1985, 34 (5): 694-699. doi: 10.7498/aps.34.694
Based upon Kubo 's linear response theory, we propose a simple quasi-particle exita-tion model of low temperature anomalous resistivity in highly disordered metallic systems.In our model, the Fermi level is deformed as a result of configurational disorder.
1985, 34 (5): 700-705. doi: 10.7498/aps.34.700
It is pointed out in this paper that there is obviously a self-field effect in small dimension Josephson junction consisting of crossed thin films when the current in the junction is asymmetrically supplied. The symmetries of I(H)-H curves would be changed by the asymmetrical self-field.
1985, 34 (5): 706-708. doi: 10.7498/aps.34.706
We propose an empirical expression of the transition temperature Tc for amorphous superconductors including a number of nontransition metals, namely Tc = Aλ〈ω〉1/2/(〈ω〉/ω0 +(1+λ)/20), here A =(1/5)(K1/2). The comparison of the calculated values with experimental data and Garland theory for Tc shows that this empirical expression can describe the Tc values of amorphous superconductors satisfactorily.