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Volume 11 Issue 6
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Original Articles
Perturbed Effect of the Gravitational Wave Produced by Microwave Electromagnetic Cavity on Detecting Electromagnetic Field
LI Fangyu, LUO Jun, TANG Mengxi
Chin. Phys. Lett. 1994, 11 (6): 321-324 .  
Abstract   PDF(pc) (205KB) ( 541 )
Perturbed effect of high-frequency gravitational radiation produced by microwave electromagnetic (EM) cavity on static detecting EM field is investigated, and corresponding perturbation solutions have been given. It is found that the gravitational wave (GW) beam propagating along symmetric axis of the cavity is purely +type polarized in transverse traceless coordinate system, and it can make the static EM field generate a cumulative perturbed effect which is proportional to the time. For the gravitational radiation wave beams propagating along other directions, they are usually mixed radiation of + and x type polarization. Quality factor of the cavity plays a key role in interaction strength of the GW with the detecting EM field.
Theory of Controlling Instability in l -D Nonlinear Systems with Adaptive Method
NI Wansun, QIN Tuanfa*
Chin. Phys. Lett. 1994, 11 (6): 325-328 .  
Abstract   PDF(pc) (202KB) ( 345 )
Theory of controlling instability based on the Lyapunov stability and the criterion of convergence for selecting the control stiffness ε and the magnitude of deviation in one dimensional nonlinear systems with adaptive method have been given. This method can be applied not only to chaotic attractor but also to the situation of bifurcations, and it is simple, reliable, efficient, and easy of automatic control.
Cluster Effect and Intermittency
GAO Chongshou, , HE Bin,
Chin. Phys. Lett. 1994, 11 (6): 329-332 .  
Abstract   PDF(pc) (195KB) ( 566 )
A new method is used to obtain two parameters about the size of hadron cluster. By comparison with the results from another method it is found that the intermittency behaviors are closely related with short-range correlation from hadron cluster.
Study of Soft Quadrupole Excitation in Nucleus 11Li with Test Particle Method
CAI Yanhuang, A. Smerzi, M. Di Toro
Chin. Phys. Lett. 1994, 11 (6): 333-336 .  
Abstract   PDF(pc) (179KB) ( 663 )
The quadrupole excitations in nucleus 11Li have been studied within the nuclear Vlasov equation approach. The classical phase space distribution function is given by the test particle propagation method. A soft mode of quadrupole excitation located around 2MeV is found. The total percentage of E2 energy-weighted sum rule exhausted in this soft resonance region is very sensitive to the extension of neutron halo in nucleus 11Li. The results compared with other recent calculations are analyzed.
A Resonant Model for Charge Transfer and Excitation in Proton-Hydrogen Collisions
PAN Limin, WANG Yansen, HUANG Fayang, FANG Dufei, TANG Jiayong, YANG Fujia
Chin. Phys. Lett. 1994, 11 (6): 337-340 .  
Abstract   PDF(pc) (144KB) ( 471 )
A new and simple model is developed to describe charge transfer, excitation and elastic process in low energy ion-atom collision in which the resonant transfer is considered as the dominant mechanism. The formulas are given in the secondary quantum representation. The cross sections of electron capture, excitation and elastic process in proton-hydrogen atom collision have been calculated and compared with experiment data.
Dendritic and Fractal Patterns in Electrochemical Deposition of Silver
LUO Guipeng, AI Zhuming, WEI Yu
Chin. Phys. Lett. 1994, 11 (6): 341-344 .  
Abstract   PDF(pc) (485KB) ( 439 )
Electrochemical deposition were carried out using silver nitrate (AgNO3), with Lang-muir monolayer at the interface of solution. Pattern formation was studied as a function of applied voltage and surface pressure. We found four different growth forms in this system. A transition from ordered dendritic crystals to disordered ramified patterns is found when the applied voltage increases most strikingly, from dendritic crystal to disordered ramified patterns, a dense two-dimensional silver film with fractal clearance is obtained.
Ferroelectric Phase Transition in Nanocrystalline Lead Zirconatitanate System by Raman Scattering
MENG Jinfang, ZOU Guangtian, LI Jiangping, CUI Qiliang, WANG Xiaohui, ZHAO Muyu
Chin. Phys. Lett. 1994, 11 (6): 345-348 .  
Abstract   PDF(pc) (221KB) ( 437 )
The Raman spectra of PbZr0.3Ti0.7O3 for different grain size as well as at high temperature and high pressure have revealed that its structure is transformed from tetragonal to quasi-cubic phase with decreasing grain size. The phase transition temperature drops down to a lower temperature and the pressure-induced phase transition can be correlated with the diffuse phase transition.
Optical Interface Phonon in Graded Quantum Well Structures
ZHU Jialin, DUAN Wenhui, GU Binglin
Chin. Phys. Lett. 1994, 11 (6): 349-352 .  
Abstract   PDF(pc) (210KB) ( 336 )
The behaviour of optical interface phonon is investigated first for the graded quantum well of Gal-xAlxAs in the dielectric continuum model. It is found that the behaviour of interface phonon modes is quite different from that in square quantum well structure. The dispersions of the interface modes are sensitive to the gradient of the graded quantum well structure, and the symmetry of modes can be changed greatly, which is important for phonon-related phenomena.
Order-Disorder Transition of Ternary Ordered Alloy
ZHENG Maosheng, LIU Yunpeng*, GAO Jiqiang, JIN Zhihao
Chin. Phys. Lett. 1994, 11 (6): 353-356 .  
Abstract   PDF(pc) (154KB) ( 572 )
Percolation transition model proposed previously for binary alloy is developed to study order-disorder transition of ternary ordered alloy. With the help of quasi-chemical approach of alloy thermodynamics, new expression for predicting order-disorder transition temperature of ternary ordered alloy is put forward. Good agreement of predictions and tests in available literature obtained.

Negative Eigenvalue Counting Method for One-Dimensional Mesoscopic Rings
ZHANG Weimin, DENG Wenji, LIU Youyan
Chin. Phys. Lett. 1994, 11 (6): 357-360 .  
Abstract   PDF(pc) (154KB) ( 458 )
Negative eigenvalue counting method has been extended to deal with the closed ring with large number of atoms threaded by a magnetic flux. This new method is extremely computer memory-saving and can be used to accurately determine the eigen-values and eigenvectors. As numerical examples, the results of second moment and persistent current are presented.
Variational Calculation for Large Bipolarons in Arbitrary Dimensions
CHEN Qinghu, WAN Shaolong, WANG Kelin
Chin. Phys. Lett. 1994, 11 (6): 361-364 .  
Abstract   PDF(pc) (178KB) ( 416 )
The calculation model of the large bipolaron binding energy proposed by Verbist et al. is extended to arbitrary dimensions including fractal dimensions. It is found that the fractal dimension D = 1.25 corresponds to the lowest critical coupling constant αc = 1.9, D = 1.73 corresponds to the highest critical ratio of dielectric constants ηc = 0.163, and when D ≤ 1.145 bipolarons can not exist for any coupling constants and ratios of dielectric constants.
Antiferromagnetism to Superconductivity Transition in the Extended Hubbard Model
YAN Xinzhong
Chin. Phys. Lett. 1994, 11 (6): 365-368 .  
Abstract   PDF(pc) (161KB) ( 420 )
By taking into account the possibility of phonon mediation, we add the Hubbard model a term of attractive interaction between the electrons on nearest-neighbor sites. There is a competition between the electrons pairing and the antiferromagnetic correlation. Using the mean-field theory, we show that there exists the superconducting phase transition in the doped system.
Extended Rate Equation for Flux Motion in High-Tc Superconductors
JI Helin, QIN Mengjun, JIN Xin, YAO Xixian, FU Yaoxian
Chin. Phys. Lett. 1994, 11 (6): 369-372 .  
Abstract   PDF(pc) (206KB) ( 434 )
The rate equation for flux motion in high- Tc superconductors is extended to take the contribution of field sweep into account in this work. It is shown that the time and field sweep rate (H) dependence of magnetization are equivalent approaches to the study of flux creep properties in high- Tc superconductors. The agreement of the effective activation energy Ueff (J) extracted from the time relaxation and that from magnetic hysteresis loops measurements on a melt-textured YBa2Cu3O6+x sample supports this extended rate equation for flux motion in high temperature superconductors.
Doping Effect on Superconducting Transition of Ba-K-Bi-O System
ZHAO Liangzhong, ZHANG Jinbiao, WANG Weihua, YIN Bo*, LI Jingwei*, ZHAO Zhongxian *
Chin. Phys. Lett. 1994, 11 (6): 373-375 .  
Abstract   PDF(pc) (121KB) ( 486 )
Chemical doping or substitutions were carried out in both the Ba site and Bi site in Ba-K-Bi-O superconductor. The large single crystals of Ba-K-M-Bi-O (M=Ca, Eu, In and T1) were prepared by using the electrocrystallization method. The resulting crystalline materials were characterized by x-ray photoelectron spectroscopy and magnetic method. The results show that partial substitutions of Ca or Eu in the Ba site suppress Tc more drastically than that of TI in the Bi site. All the present chemical substitutions result in a decrease in Tc.

A Suggestion to the Designing of Ceramic Superconductors with Higher Transition Temperatures
CHENG Kaijia
Chin. Phys. Lett. 1994, 11 (6): 376-378 .  
Abstract   PDF(pc) (172KB) ( 371 )
This short note gives a series of possible candidates of the substitutional elements that could replace the element Y in YBCO and raise the transition temperature. The ground is of two folds. The atom of the substitution should possess a higher electronic surface density so that it will compress the remaining atoms and results in a decreasing of the atomic spacing and therefore in an increasing the energy gaps of Brillouin zones. Secondly according to author's double- band theory of superconductivity, transition temperature should be proportioned to the second power of the energy gap, above which the superconductive electrons reside in. Hence a high electronic surface density will raise the transition temperature. Calculation shows that the most prospective substitutional elements would be Ir, Au or W. However tungsten is recommended due to its valence character of the oxide in the sintering process.
Role of Residual O2 in Fabrication of A1-MgF2-Au(Cu) Thin Film Devices
ZHENG Keqin, SHU Qiqing, CHEN Xinyong
Chin. Phys. Lett. 1994, 11 (6): 379-382 .  
Abstract   PDF(pc) (183KB) ( 433 )
After the light emitting device Al-MgF2-Au (Cu) junction was reported, we made a further investigation about its structure, high voltage-resistance, explaination of l-V characteristic and mechanism of light emission of these junctions through analyzing in detail. The residual O2 during fabricating the junctions plays an important role in the properties of the junctions.
Optical Transitions in Cr Doped Bi4Ge3O12 Crystal
HUANG Yingpeng, FENG Xiqi, HU Guanqin, YANG Baocheng, LING Yuanqi, PANG Weizhou, ZHU Jikang
Chin. Phys. Lett. 1994, 11 (6): 383-386 .  
Abstract   PDF(pc) (156KB) ( 568 )
In this paper, we present the results of the optical absorption spectra of Cr doped Bi4Ge3O12 crystal at room temperature and compare them with the theoretical results of a multifold scattering (MS)-Xα calculation which include the energy-level structures and the transition energies of Cr3+ and Cr4+ located in Ge-site in the crystal.
Photoluminescence and Electroluminescence of Poly p-Phenyl Phenol Prepared by Enzymatic Catalyzed Polymerization
MA Yuguang, TANG Jianguo, MA Lin, LIU Shiyong, SHEN Jiacong
Chin. Phys. Lett. 1994, 11 (6): 387-389 .  
Abstract   PDF(pc) (151KB) ( 481 )
The photoluminescence (PL) peak of poly p-phenyl phenol (PPP) is at about 370-420nm excited by the light at 350nm. The absorption band edges and photon emitting peaks of the polymer are found the conjugated lengths dependent on molecular weight of polymer. In the transient luminescence measurement the lifetime of PL decay is determined to be 2.0ns which is supposed an evidence of polaron excitation recombination. The electroluminescence is observed with aluminum/PPP/indium- tinoxide cell.
Evidence of the Nano-sized Si Microstructure of Porous Si From Scanning Tunneling Microscopy
WENG Yumin, YANG Xinju, CHEN Yufeng, ZONG Xiangfu
Chin. Phys. Lett. 1994, 11 (6): 390-392 .  
Abstract   PDF(pc) (231KB) ( 405 )
Scanning tunneling microscopy was used to observe the morphological feature of luminescent porous Si Results show that the surface of porous Si consists of randomly distributed nano-sized Si grains, which may be Si clusters. No clear interface was found between the grains. Its microstructure looks like a sponge. Visible photoluminescence in porous Si is most likely due to the carrier confinement in this microstructure.
Evolution of Overlap in Hopfield Network with Continuous Transfer Function
JI Daoyun, ZHOU Changqi, CHEN Tianlun
Chin. Phys. Lett. 1994, 11 (6): 393-396 .  
Abstract   PDF(pc) (186KB) ( 402 )
The evolution of overlap which is easily obtained in Hopfield neural network with continuous hyperbolic tangent thresholding function is equivalent to that in corresponding two-state neural network with finite temperature. The attractors of two simple cases, the Hopfield model with independent random patterns and pair correlated patterns, are analyzed.
Non-stationary Black Hole and Hawking Radiation in 1+1 Dimensions
LI Zhongheng, ZHAO Zheng*
Chin. Phys. Lett. 1994, 11 (6): 397-400 .  
Abstract   PDF(pc) (93KB) ( 431 )
A non-stationary solution of the field equation in 1+1 dimension gravity is given with the advanced Eddington-Finkelstein coordinate. There exists a 1 +1 dimensional non-stationary black hole in the space-time. The location of event horizons, the Hawking temperature and the spectrum of thermal radiation are derived.
21 articles