Vol. 34, No. 8 (1985)
1985, 34 (8): 983-991. doi: 10.7498/aps.34.983
A new approach to nonlinear electronic transport in solids is described briefly and is applied to the discussion of combined acoustic and optical phonon. scattering. It is found that although a relatively flat region may exist in the currenit-versus-field curve if the scattering by optical phonon is strong, the saturation of the current density, which occurs in the case of pure optical scattering, disappears and the acoustic phon-ons are always important at high current density.
1985, 34 (8): 992-999. doi: 10.7498/aps.34.992
In this paper, we report the calculation results of bifurcation diagrams in liquid crystal (LC) hybrid optical bistability. The x-A and x-xB bifurcation diagrams and A-xB phase portrait are given. The symmetry of the bifurcation diagram, the sudden change and hysteresis phenomena of chaotic regions, and the effect on the structure of chaotic regions caused by LC transmitance function with two peaks are observed.
X-ray diffraction and polarized neutron diffraction measurements have been made on metallic glass Co81.5 B18.5. The partial structure factors, Sij(Q), and partial reduced RDF, Gij(r), are obtained by applying two different data analysing procedures, these results are compared in conjunction with the experiment done by other workers. The neutron scattering intensity of a simple model has been simulated, and the structure model of this glass is finally discussed.
TEMPERATURE DEPENDENCE OF THE MAGNETIZATION AND ELECTRICAL RESISTIVITY FOR AMORPHOUS Fe87-xSixB13 ALLOYS
1985, 34 (8): 1009-1016. doi: 10.7498/aps.34.1009
The magnetization and eleetrcal resistivity as a function of temperature for amorphous Fe87-xSixB13 (x=0, 9.6, 14.5) alloys were studied. It is obtained that Curie temperature Tc and crystalline temperature Tcr increases markly with increasing Si content. The temperature dependence of magnetization at low temperature is in accordance with Bloch T3/2 law. Calculation shows that the spin wave stiffness constant D increases with increasing Si content from 62meV·A2 to 111 meV·A2 δ=〈△J〉1/2/〈J〉 value obtained from D is close to that calculated by Handrich theory. The resistivity minima phenomena have been observed at low temperature for x=0, 9.6 and 14.5. The temperature of resistivity minima Tmin increases with increasing Si content from 10.5K for x=0 to 24.6 K for x=14.5. The temperature dependence of the resistivity are linear and quadratic near room temperature and in the range Tmin≤T≤130K, respectively. A discussion of this phenomenon is given in terms of a generalized Ziman theory.
1985, 34 (8): 1017-1026. doi: 10.7498/aps.34.1017
Thermodynamic properties of Y2O3·Cr2O3 were determined by means of electromotive force (emf) measurements using stabilized zirconia as a solid electrolyte at 1182 -1386 K. The constructions of oxygen concentration cell was Mo|Cr, Y2O3, Y2O3·Cr2O3|ZrO2(+MgO)|Cr, Cr2O3|Mo Using the emf values and its temperature dependences of the above cell, the standard free energy of formation of Y2O3·Cr2O3 according the reaction Y2O(3(s))+Cr2O(3(s)) = Y2O3·Cr2O(3(s)) was obtained as△G0((Y2O3)·cr2o3) = 39160- 34.97T( error in experiment is±350 cal/mol) or △G0((Y2O3)·cr2o3)= 163900-146.3T (error in experiment is±450J/mol) According the linear equation △G°= a + bT and equation △G = △H - T△S, the average enthalpy and entropy in the temperature ranges of investigation may beassumed as △H0((Y2O3)·cr2o3) = 39160 cal/mol or 193900J/mol, △S0((Y2O3)·cr2o3) = 34.97 cal/(mol ·K) or 146.3J/(mol·K).
1985, 34 (8): 1027-1033. doi: 10.7498/aps.34.1027
The effect of dispersed second phase particles of γ-Al2O3 on the ionic conduction of β-Li2SO4, has been studied. The electrical conductivity of β-Li2SO4 (γ-Al2O3) increases remarkably with the addition of γ-Al2O3. The maximum increment appears at about 50 mol%γ-Al2O3. The conductivity of β-Li2SO4 (50mol% γ-Al2O3) is four orders of magnitude higher than that of pure β-Li2SO4 at 253℃. On the other hand, the conductivity in α-Li2SO4 containing γ-Al2O3 decreases. The conductivity of β-Li2SO4 (γ-Al2O3) prepared in the condition of 70-80% relative humidity increases monotonically with γ-Al2O3 content. The additional small peaks of 7Li NMR absorption spectral in these specimens were found to be more obviously with the increasing of γ-A12O3 content. The obsorption water layers on surfaces of γ-A12O3 particles are responsible for this phenomina. It is also found that quenching of the sintered β-Li2SO4 (30mol%γ-A12O3) pellet has evident effect on conductivity. The conductivity of quenched specimen is two orders of magnitude higher than that of the unquenched.
1985, 34 (8): 1034-1039. doi: 10.7498/aps.34.1034
The response of an atomic tri-level system to laser pulses was analyzed and the condition for forming tri-level echo was obtained. This new echo has been observed experimentally and used to measure the collisional cross-section between │32D〉+│32P3/2>〉 Na and Ar.
1985, 34 (8): 1040-1048. doi: 10.7498/aps.34.1040
The, output of a pulsed dye-laser pumped by a frequency-doubled Nd: YAG laser is focused into a heat-pipe oven. The optical wave-mixing processes and parametric oscillations from two-photon excitation of 5d2DJ state in potassium vapor are investigated. Twenty-eight coherent lines within the range of 302-421 nm are generated. Splits and frequency shifts of the parametric oscillations and wavelengths and relative intensities of spectral lines in the wave-mixing processes are explained with a theoretical analysis based on the wave equation, atomic polarization and phase-match condition. The theoretical values are found to be in agreement with the experimental results.
SPECTROSCOPIC OBSERVATIONS ON THE LINE STARK BROADENING IN THE VACUUM ULTRAVIOLET IN LASER-PRODUCED PLASMAS
1985, 34 (8): 1049-1055. doi: 10.7498/aps.34.1049
The emission from dense plasmas produced by a Q switched ruby laser pulse focusing on plane targets of the elements Be, C and N has been observed in the vacuum ultraviolet at various distances from target surface. For recording the emission spectra an intensified photodiode array and an optical multichannel analyzer have been implemented. Very broad lines of the type △n=l of the H-like He-like and Li-like ions arising from relatively high principal quantun number n appear prominent in the spectra. And according to the ion quasistatic approximation theory the electron densities of the plasmas as the function of the distances from the target surface have been derived.
1985, 34 (8): 1056-1063. doi: 10.7498/aps.34.1056
A new correction method for quantitative microanalysis of light elements is described in present article. The various correction factors in this method are determined by using Monte Carlo computing technique. We have performed microanalysis on. carbon and oxygen. The results of concentration obtained are much better than other methods. In reviewing ZAF method, The simple Philibert absorption correction and Duncumb-Reed. atomic number correction are discussed in detail, and their limitations are shown.
This paper presents the results about the low angle grain boundaries observed in HCP metal α-Ti by TEM. Not only the tilt boundaries but also the twist boundaries formed on basal plane and prism plane have been observed. In the dislocation network lain on prism plane, type c dislocations have been observed but their movement has never been disclosed. This may be related to the high Peierls stress of type c dislocations.
1985, 34 (8): 1068-1074. doi: 10.7498/aps.34.1068
The hydrostatic pressure coefficient of gold acceptor levels Er in Silicon was measured by transient capacitance method. Under the pressure range of 0-8 Kbar, thepressure coefficient (?(Ec-ET))/(?P) =-1.9 meV/kbar. The electron capture cross section of gold acceptor centers does not depend on pressure within the experimental accuracy. By comparing the present result of hydrostatic pressure coefficient with the uniaxial pressure coefficient reported in , we conclude that the defect potential is lack of Td symmetry. Therefore, the gold acceptor levels are not originated by simple gold substitutional or interstitial configuration in Si crystals.
1985, 34 (8): 1075-1079. doi: 10.7498/aps.34.1075
The effect of the coulomb interaction on electrically neutral, localised states of conjugated polymers is investigated using a tight binding Hamiltonian. For trans- (CH)x, we calculated the excitonic spectrum, recalculated the absorption coefficient, and corrected the edge of the absorption profile. The results are shown to be in good agreement with experiments.
1985, 34 (8): 1080-1083. doi: 10.7498/aps.34.1080
This note deals with a new nonlinear circuit which is the forced second order unijunction transistor oscillator. It can exhibit period bifurcation and chaotic behavior when driving parameter varies in a large range.
1985, 34 (8): 1084-1087. doi: 10.7498/aps.34.1084
The contribution of the ghost particle to the vacuum energy (Casimir energy) and the influence of various covariant gauges on the vacuum energy are calculated in the U(l) gauge field theory by using the Peynman path integral method.
THE ELASTIC CONSTANTS CijE, AND CijD, OF LiNbO3 DETERMINED BY THE ULTRASONIC "PULSE ECHO OVERLAP METHOD"
1985, 34 (8): 1088-1095. doi: 10.7498/aps.34.1088
Based on the fundamental piezoelectric Christoffel's equation, we derived the expression of the elastic constants for piezoelectric crystal with trigonal symmetry point group 3 m. The ultrasonic wave velocities in LiNbO3 crystal, propagating along different crystallographic directions, are determined by the "pulse echo overlap method". The. carrier frequency of rf pulse is 10 MHz. The Values of the secondorder elastic constants CijE and CijD for LiNbO3 crystal are obtained as follow: C11E = 19.89, C12E = 5.25, C13E = 7.81, C14E = 0.96, C33E = 25.44, C44E = 6.10, C66E=7.32×1010N/m2·C11D = 21.51, C12D= 3.65, C13D = 7.91, C14D=-1.41, C33D = 26.10,C44D = 9.62, C66D = 8.93×1010N/m2.
1985, 34 (8): 1096-1101. doi: 10.7498/aps.34.1096
The shift of frequencies of Si—H infrared absorption spectra in solid state silicon in comprarison with those in gaseous subsilane was interpreted. The results showed that SiHx groups similar to subsilane molecule exist in solid state silicon.
1985, 34 (8): 1102-1106. doi: 10.7498/aps.34.1102
This article reports a new type InGaAsP/InP bistable DH laser (BSDH) formed by proton bombardment with internal modulation on Q factor. The typical bistability exhibiting in L-I curve in these BSDH has been obtained. The current range of bistable operation are 50 mA, 200 mA measured in two samples, respectively. The value can be varied by selecting the device parameters. It is very interesting that the laser light emitted from BSDH operating with various injection currents has a high stable single longitudinal mode. The peak wavelength is 1.2596 μm and the stability on wavelength is about 10-5.Finally, a qualitative discussion is given.
DyP5O14 crystal with monoclinic I (P21/c) phase was found and was verified by optical microscopy, X-ray structure analysis and infrared spectroscopy. DyP5O14 crystal with monoclinic I phase contains mmmF2/m ferrolastic domain. The temperature of ferrolastic phase transition is 159±3℃. The lattice parameters of DyP5O14 crystalwith monoclinie I Phase are a = 8.62 ?, b = 8.84?, c = 12.82?, β= 90.68°.