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Vol. 28, No. 3 (1979)

1979-02-05
CONTENT
THE GROWTH OF FACETS AND VICINAL INTERFACES ON CZOCHRALSKI-GROWN YAG SINGLE CRYSTALS
MING NAI-BEN, YANG YONG-SHUN
1979, 166 (3): 285-296. doi: 10.7498/aps.28.285
Abstract +
In this paper, we studied the macro-morphology and micro-structure of crystal-molt interfaces, which was exposed by rapid separating the growing crystal from the melt. We have determined the indices of the facets revealed on the interface of Czochralski-pulled YAG single crystals with various orientations. The facets have been discovered on the concave interface as well as on convex interface of -oriented grown YAG single crystals. We have observed the micro-structure of vicinal interface, which is composed of sections of singular surface dispersed with steps. The experimental evidence for the step movement as well as the interaction of steps with inclusions on these interfaces is presented.The micro-structure of the interfaces and the correspondence between the facets and the core for concave interface growth are discussed, and it is implied that the macro-shapes of interface influence the micro-mechanism of growth. The growth mechanism for concave and convex interfaces based on these considerations is then developed.
ON REDUCTION OF THE HIGH ORDER TWINNING IN FCC STRUCTURE TO A SINGLE ROTATION RELATIONSHIP
ZOU BEN-SAN, YE HENG-QIANG, WU YU-KUN, GUO KE-XIN
1979, 166 (3): 297-304. doi: 10.7498/aps.28.297
Abstract +
By following the relationship of correspondanee between twinning geometry and the rotation matrices, and the combination theorems of rotation operation, it is always possible to reduce the multiple twinning operation of the high order twin to single rotation operations. In this article, we calculated the rotation axis [uvw] and rotation angle φ 's, by which the reduction of 1-5 order twinning in the fee structure to single rotation operations can be accomplished. In addition, we also give the computing procedure which is appropriate for the automatic analysis of electron diffraction pattern of high order twins by means of a computer.
RELAXATION BEHAVIORS OF THE LIGHT DIFFRACTION INTENSITY AND RELATED "FREEZING" EFFECT AT LOW TEMPERATURES OBSERVED IN α-LiIO3 SINGLE CRYSTALS UNDER THE ACTION OF AN ELECTROSTATIC FIELD
ZHAO SHI-FU, GU BEN-YUAN, ZHANG AN-DONG, XU ZHENG-YI
1979, 166 (3): 305-313. doi: 10.7498/aps.28.305
Abstract +
On the basis of our earlier work, the relaxation behaviors of the light diffraction intensity induced by the distribution of space charge in a-LiIO3 single crystals under the action of an electrostatic field have been investigated by using a space filter. The empirical expressions of the relaxation process were obtained. It was found that the parameters involved change with the temperature and from specimen to specimen, as well as depend both on the magnitude and the relative direction of the polarity of the crystal and the electrostatic field applied. When the temperature is lowered below a certain value (≈-25℃), the enhancement diffraction intensity due to the applied field becomes not quite evident. When the electrostatic field is applied at a temperature higher than the "freezing" point and then the specimen is cooled to a temperature below the latter, the magnitude of diffraction intensity enhanced by the applied voltage at higher temperatures remains unchanged, it is so even after removing the voltage. This "freezing" effect is parallel to that observed in the enhancement of neutron diffraction intensity.
A USEFUL METHOD FOR INDEXING ELECTRON DIFFRACTION PATTERNS
LI CHUN-ZHI
1979, 166 (3): 314-323. doi: 10.7498/aps.28.314
Abstract +
In this paper, general expressions for coordinate transformation in crystal direct space or reciprocal space are derived by using of matrix calculus. A matrix method for indexing complex electron diffraction patterns of two phase structures, twins and high order Laue zones is described.
THE BLOCKING EFFECT OF Si, GaAs AND LiNbO3 SINGLE CRYSTALS
CHEN CHANG, WEI CHENG-LIAN, DONG YU-LAIN, LIU SHI-JIE, XIA GUANG-CHANG, FAN JING-YUN, WANG QI-LIANG, GAO ZHI-WEI
1979, 166 (3): 324-333. doi: 10.7498/aps.28.324
Abstract +
By making use of the back scattering method Si, GaAs and LiNbO3 Single Crystal blocking patterns were obtained and GaAs single crystal {110}, {100} and {112} plane blocking halfangle ψ1/2 values were estimated. We have found that the depth of the {110} plane blocking dip of Si slice damaged due to ion implanting becomes shallow when implantation dose increases. In order to check the experimental apparatus and the method, we have also obtained Si single crystal blocking pattern and measured the values of Si single crystal {110}, {111} and {100} crystal plane blocking halfangles
THE POSSIBILITY OF THE CRYSTALLIZATION OF METASTABLE GRAPHITE FROM MOLTEN METAL SOLUTIONS UNDER THE STABLE CONDITIONS OF DIAMOND
LIU GUANG-ZHAO
1979, 166 (3): 334-340. doi: 10.7498/aps.28.334
Abstract +
The experimantal phenomena for the formation of graphite, -the metastable phase of carbon -from molten metal solutions under ultrahigh pressures and high temperatures are given. Taking this as an example, we have analyzed the thermodynamic possibility of the crystallization of the metastable phases from the solution. The concept of supersaturation that promotes the metastable phases to crystallize from solutions has been presented. It has been pointed out that the temperature difference in a solution system must be the driving force for crystallization of the metastable phase from, the solution. The emphasis is placed on the calculations of the critical temperature difference of the possible crystallization for the metastable graphite under a given crystallizing condition.
MEASUREMENT OF CARRIER LIFETIME OF GaAs DIODES WITH p-n AND M-S JUNCTIONS BY STEP RECOVERY METHOD
WANG WEI-YUAN
1979, 166 (3): 341-349. doi: 10.7498/aps.28.341
Abstract +
This paper presents some preliminary results on the measurement of carrier lifetime of GaAs diodes by the step recovery method. The lifetime of Si recovery diodes with Boron diffused p-n junction has been measured by the reverse recovery and step recovery methods.The results obtained are fairly consistent, indicating that it meets the requirement of the step recovery method sufficiently well. Therefore, it is suggested that the diode lifetime so obtained is equal to the minority carrier lifetime. In this way, the minority carrier lifetime of GaAs diodes with p-n junction has been determined. The lifetime of GaAs diodes with M-S schottry barrier has also been measured. In this case, however, it is suggested from a preliminary analysis that the measured value is not the minority carrier lifetime.
MEASUREMENT OF DEEP LEVEL TRAPS IN GaAs
ZHOU BING-LIN, WANG LE, SHAO YONG-FU, CHEN QI-YU
1979, 166 (3): 350-357. doi: 10.7498/aps.28.350
Abstract +
Measurements on transient capacitance and thermally stimulated capacitance of N-type GaAs epitaxial materials have been carried out. Electron traps could not be detected in LPE materials. However, two electron traps 0.82 and 0.43 eV below the conduction band have been discovered in VPE materials, the electron capture sections are found to be about 2.0×10-13 and 1.5×10-15cm2 respectively.
A DISCUSSION ON THE GENERALIZED LINEAR COHERENT OPTICAL-PROCESSING SYSTEM
ZHAN DA-SAN
1979, 166 (3): 358-363. doi: 10.7498/aps.28.358
Abstract +
In this article, we discuss the properties of the generalized linear coherent optical-processing system proposed in [1] and [2], and show that the equivalent system exists. We further show that the parameter Z1 is of little importance.
COMPUTER SIMULATION OF LASER IMPLOSIVE COMPRESSION OF A D T TARGET AND ANALYTIC SOLUTIONS ON THE SHOCK WAVES AND THERMAL WAVES
TAN WEI-HAN
1979, 166 (3): 364-376. doi: 10.7498/aps.28.364
Abstract +
On the basis of analysing the results of a computer simulation of one-dimensional double-temperature laser implosive compression of a DT target, the author has found the analytic solutions on the shock waves and thermal waves which are in good agreement with the computer results.
INFLUENCE OF THE TERMINAL LEVEL LIFETIME ON Nd-GLASS LASER AMPLIFIERS
DENG HE
1979, 166 (3): 377-382. doi: 10.7498/aps.28.377
Abstract +
In this paper, influence of the terminal level lifetime on Nd-glass laser amplifiers has been investigated by using a computer. Results show that, for a Nd-glass laser amplifier with dimension of φ20×480 mm, when the Nd-glass terminal level lifetime is decreased from 100 ns to 1 ns, the influences on an input pulse with a 20 ns width and 2.0 J/cm2 energy density are as follows: the gain increases by~20%; the distortion of the pulse peak decreases by~20%; and the amplifier's saturation length decreases by~30%.
LINE WIDTHS AND ENERGY SHIFTS OF SPONTANEOUS EMISSION
DENG CONG-HAO
1979, 166 (3): 383-392. doi: 10.7498/aps.28.383
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In this paper, we carry out the theoretical calculation of line widths and energy shifts of spontaneous emission, the decaying oscillating field is taken instead of the free field as the action field. In the calculation the self consistent requirement is imposed.The method of calculation is rigorous but different from the previous workers. No divergence difficulties are encountered in the calculation.We think this method of avoiding divergence difficulties may be useful in the theoretical calculation of inelastic scattering cross sections in elementary particle physics.
THEORY OF THE SUPERCONDUCTING CRITICAL TEMPERATURE (Ⅲ)
CAI JIAN-HUA, GONG CHANG-DE, WU HANG-SHENG, CAI JUN-DAO, JI GUANG-DA
1979, 166 (3): 393-405. doi: 10.7498/aps.28.393
Abstract +
We have determined the first several coefficients of the series formula (1) for superconducting Tc. For the double-σ spectrum as α2F(ω)=λω/2[a1δ(ω-ω1)+(1-a1)δ(ω-ω2)] and that of several real materials, we have compared the Tc calculated from the series formula, the Allen-Dynes formula and the numerical solution of the Eliashberg Equation, respectively. The results suggest that when the series is convergent, the calculated results by using the series formula is a better approximation of the numerrieal solution than that from the A-D formula.We have also given an approximate Tc series formula, obtained a method to estimate the convergent radius of the Tc series and calculated the convergent radius for several materials. Therefore we may estimate the region in which the series formula (1) is valid.
THE EFFECT OF ALLOY ELEMENTS ON THE Nb3Sn GROWTH KINETICS
PEKING UNIVERSITY DIVISION No.7, METAL INTERFACE RESEARCH GROUP
1979, 166 (3): 406-415. doi: 10.7498/aps.28.406
Abstract +
The effect of alloy element Zr on the Nb3Sn growth kinetics at the Cu-Sn/Nb interface has been investigated. Experiments have revealed that the addition of Zr in single core composites increases the growth rate substantially and the variation of the Nb3Sn layer thickness with reaction time obviously exceeds the parabolic law. These results cannot be interpreted fully taking into account the fineness of Nb3Sn grains caused by the ZrO2 particles formed during heat treatment, and it is necessary to consider the increase of diffusion coefficient caused by supersaturation of vaeances around the ZrO2 particles. The depletion of Sn contents in the Cu-Sn matrix of multifilamentary composites during heat treatment greatly influenced the growth rate. The revised formula of growth kinetics gives a satisfactory explanation on the experimental results.
THE CURRENT STEPS IN SUPERCONDUCTING WEAKLINKS
YAO XI-XIAN
1979, 166 (3): 416-425. doi: 10.7498/aps.28.416
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In the presence of a battery source and a radiation field, a superconducting weaklink can be represented by a simplified model consisting of a resistance shunted Josephson junction driven by a constant current source. Using such a model, we give a general criterion for the occuring of constant voltage current steps in the current-voltage characteristics of the weaklink. Following this criterion, we have also discussed the absence of sub-harmonic current steps. For the case while the radiation field is very weak, the current step heights are calculated by pertubation method. The current step heights are also obtained by numerical compution for the case of strong field.
BRIEF REPORT
A CRITERION ON THE STABILITY OF A15 PHASES
WANG WEN-KUI
1979, 166 (3): 435-442. doi: 10.7498/aps.28.435
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