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Volume 7 Issue 7
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Original Articles
HYSTERESIS OF PSEUDOELASTICITY IN A SINGLE CRYSTAL WITH SHAPE MEMORY EFFECT
XU Huibin
Chin. Phys. Lett. 1990, 7 (7): 289-291 .  
Abstract   PDF(pc) (45KB) ( 344 )
The size of hysteresis loops and interior loops in pseudoelasticity were investigated with CuZnAl memory single crystal. The results show that the width of the hysteresis loop does not change significantly with temperature; while the size of the interior loops of hysteresis strongly depends on the martensitic phase fraction induced from austenit.
EXPERIMENTAL INVESTIGATION OF ELECTRONS IN HELIUM GLOW DISCHARGE
TANG Xiaowei*, CAO Jinxiang, LIN Xianghong, BIAN Zuhe, JIANG Yong
Chin. Phys. Lett. 1990, 7 (7): 292-295 .  
Abstract   PDF(pc) (51KB) ( 371 )
An experiment dealing with Pauli's exclusion principle was carried out by using a glow discharge device. The main purpose of the experiment is to examine the possibility of existence of anomalous electrons by measuring the characteristic K X-rays of the anode atoms. The electrons in helium glow discharge collected by the metal anode will be captured to the inner shell if they are not identical with the electrons of the anode metal. The experimental results show that the properties of the electrons both in helium glow discharge and metal atom are identical.
PROPAGATION EFFECT OF COHERENT OPTICAL PULSES IN DISSIPATIVE TWO-LEVEL SYSTEM
JIANG Mengheng, LIN Fucheng
Chin. Phys. Lett. 1990, 7 (7): 296-299 .  
Abstract   PDF(pc) (52KB) ( 422 )
By means of the Bloch equations coupled with Maxwell equations, we treated the propagation effect of coherent optical pulses in dissipative two-level system. In such system we observed the special transient coherent phenomena which include the stair-like decrease of pulse area and periodic spatial oscillation of the ionized particles.
GENERATION OF 30ps PULSE FROM A SHORT CAVITY DYE LASER PUMPED BY A COPPER BROMIDE LASER
ZHU Lei, QIAN Liejia, ZHANG Guiyan, SONG Xiudong, LIN Fucheng
Chin. Phys. Lett. 1990, 7 (7): 300-303 .  
Abstract   PDF(pc) (66KB) ( 484 )
The transient phenomena of output from a short cavity dye laser (SCDL) pumped by a copper bromide laser are investigated. For the first time a 30ps dye laser pulse was generated, wing the SCDL with Rh6G and DODCI dissolved in ethanol.
SELF-PUMPED PHASE CONJUGATION (K0.5Na0.5)2y(Sr0.61Ba0.39)1-yNb2O6AT 633nm
YUE Xuefeng, SHAO Zongshu, CHEN Huanchu, SONG Yongyuan, SUN Daliang, WU Xiaoguang*
Chin. Phys. Lett. 1990, 7 (7): 304-307 .  
Abstract   PDF(pc) (60KB) ( 367 )
Self-pumped phase conjugation has been observed in Ce-doped (K0.5Na0.5)2y(Sr0.61Ba0.39)1-yNb2O6 (KNSBN) crystal at 633nm by using He-Ne laser. The phase conjugate reflectivity as high as 40% was measured. The reflectivity as function of incident angles and the relation of response time to the incident intensities were studied experimentally.
STUDY OF THE QUALITY OF GaAs THIN FILM ON Si SUBSTRATE BY X-RAY DIFFRACTION METHOD
LI Chaorong, MA Zhenhong, CUI Shufan, ZHOU Junming, Wang Yutian*
Chin. Phys. Lett. 1990, 7 (7): 308-311 .  
Abstract   PDF(pc) (52KB) ( 371 )
Different diffraction lattice planes were used to investigate the quality profiles of molecular beam epitaxy epi-layer GaAs films on Si substrate by X-ray double crystal diffraction method. As the X-ray incident angle increasing, the full width of half maximum (FWHM) also increases, that is , the quality getting worse in deeper layer. Therefore a clear figure of the degree of perfectness along the depth can be shown. The sample with strain surerlattice buffer layer has better quality than that without, especially in the surface lamella.
COMBINED ANALYSIS OF DEFECT CONFIGURATION OF DEFORMED BRASS BY POSITRON ANNIHILATION AND X-RAY DIFFRACTION
TENG Feng en, LIU Baozhang, LI Yanqin
Chin. Phys. Lett. 1990, 7 (7): 312-315 .  
Abstract   PDF(pc) (43KB) ( 421 )
The microstructure of alpha brass deformed to various degree ε was examined with positron annihilation technique and X-ray profile analysis. Stretch stress δ, positron annihilation probabilities Γ1, effective subgrain size Deff, positron lifetime T1 , dislocation density ρ, positron lifetime T2 and T etc. were measured as functions of deformation degree ε . Combined analyses of these curves were performed and positron annihilation models of single vacancy, dislocation, vacancy group and microvoid were suggested.

PHASE TRANSFORMATION OF GRADIENT Pd-Si FILMS
QIN Yong, LI Zongquan
Chin. Phys. Lett. 1990, 7 (7): 316-318 .  
Abstract   PDF(pc) (43KB) ( 435 )
The phase transformation of Pd-Si films with a compositional gradient is studied by means of transmission electron microscopy. The as-prepared films have a fcc structure. A variety of phases appear when the film is heated, showing the compositional dependence of the phase transformation for Pd-Si films.
STUDY OF THE PROPERTIES OF INFRARED INTERSUBBAND TRANSITION IN DOPED GaAs/A1xGa1-xAs MULTIPLE QUANTUM WELLS
CHEN Zhenghao, CUI Dafu, ZHOU Junming, PAN Shaohua, HUANG Qi, ZHOU Yueliang, LÜ, Huibin, XIE Yuanlin, FENG Simin, YANG Guozhen*
Chin. Phys. Lett. 1990, 7 (7): 319-322 .  
Abstract   PDF(pc) (52KB) ( 387 )
The properties of intersubband transition of GaAs/A1xGa1-xAs multiple quantum wells with various well widths and doped-well concentrations have been studied. Both theoretical and experimental results are in good agreement. For the appropriate well width and higher doping concentration, we directly observed two intersubband absorption peaks from E1 →E2 and E2→ E3 transitions in well. The experimental results and theoretical analysis are given.
FLUX CREEP IN HIGH Tc Bi1.7Pb0.3Sr2Ca2Cu3Oy BULK SUPERCONDUCTOR
CAO Xiaowen, HUANG Sunli, ZHANG Yuheng*
Chin. Phys. Lett. 1990, 7 (7): 323-325 .  
Abstract   PDF(pc) (45KB) ( 296 )
There was strongj7uz creep accompanied by flux jump in high Tc Bi1.7Pb0.3Sr2Ca2Cu3Oy bulk superconductor. The thermal activation energy Uo is estimated to be 0.02eV.

HIGH-Tc SUPERCONDUCTING PROPERTIES OF YBa2Cu3-xSnx O7-y SYSTEM
WANG Yuxia, RUAN Yaozhong, TAN Yudong, WANG Xiaozhong, ZHOU Guien*, FAN Chenggao*, ZHANG Yuheng*
Chin. Phys. Lett. 1990, 7 (7): 326-329 .  
Abstract   PDF(pc) (59KB) ( 356 )
The effect of Sn concentration on the superconducting properties and structure of YBa2Cu3-xSnx O7-y system were systematically investigated. The zero resistance temperature was found to be above 90K as z ranges from 0 to 1.1. For x > 1.3, the system exhibited no superconducting properties at liquid nitrogen temperature. The results of X-ray diffraction showed a regular pattern of mixed structures of 123 phase and a new phase in the system with the increase of Sn concentration. TEM analysis suggested that the new phase might be BaSnO3 with deformed perovskite structure and about 6% of Cu were substituted by Sn in the 123 phase at x = 1.0. It is therefore likely that the new phase modulates the structure of 123 phase and stabilize the 123 phase. Although the Sn atoms enter 123 phase and occupy the Cu sites in the Cu-O chain and break the chain, the system remains with Tc > 90K. Consequently, the Cu-O chain plays a less important role in the high-Tc superconductivity.


SIMULTANEOUS INCREASE OF REMANENCE AND COERCIWTY OF Nd-Fe-B MAGNETS BY Nb ADDITION
YIN Malie, HU Jifan, LIU Yinglie, WANG Zhenxi, LIN Wengui
Chin. Phys. Lett. 1990, 7 (7): 330-333 .  
Abstract   PDF(pc) (124KB) ( 321 )
The Nd-Fe-B magnets with Nb addition prepared by a new method exhibit an unusual increase of Br instead of normal monotonous decreasing tendency when the Nb content exceeds 1.75wt.%. The microstructure of these samples were studied, and it u found that the Nd-rich phase, which usually exists in Nd-Fe-B magnets, is very hard to be detected.
A NEW NONLINEAR OPTICAL MATERIAL-ORGANOMETALLIC COMPLEX TRIALLYLTHIOUREA MERCURY CHLORIDE
YUAN Duorong, ZHANG Nan, TAO Xutang, XU Dong, JIANG Minhua
Chin. Phys. Lett. 1990, 7 (7): 334-336 .  
Abstract   PDF(pc) (40KB) ( 512 )
Tri-allylthiourea mercury chloride (ATMC), an organometallic complex, is a new nonlinear optical material with high second harmonic generation (SHG) effect. The SHG effect of ATMC is three times as large as that of urea crystal. Transparent single crystal of 15X 15 X 10mm3 has been grown. Comprehensive studies of crystal growth, structure, and general properties have been carried out. The results show that organometallic complexes are promising nonlinear optical materials for wide applications.

13 articles