Table of Content

31 March 1988, Volume 6 Issue 1

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Articles

NONLINEARITY OF DIELECTRIC RESPONSE IN KTaO₃ CERAMIC AT LOW TEMPERATURE

CHEN ZHIXIONG, WANG LI, L. E. CROSS

1988, 6(1):  1-5. 

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KTaO₃ ceramic with excellent dielectric properties has been made by hot isostatic pressing (HIP).
In order to study the nonlinear properties of KTaO₃ ceramic at low temperature, we measured the electric-field dependence of dielectric constant under bias field up to 16 kV/cm and between temperatures from 4.2 K to 100K.
It was found that dielectric constant depends on the bias field at temperatures below 60K and the nonlinearity of dielectric response rises strikingly with decreasing temperature. It is related to the incipient ferro-electricity of KTaO₃ ceramic at low temperature.
We evaluated the values for nonlinear dielectric response coefficients of KTaO₃ ceramic while the Devonshire model was used to fit the experimental data. The values were compared with that of the nonlinear dielectric response cofficients of KTaO₃ single crystal which had previously been obtained by both measuring dielectric constants and the phonon frequencies of transverse optical modes in the presense of bias fields.

REGULATION AND CONTROL OF MOLECULAR PARAMETERS OF TELECHELIC POLYMERS

YAN DEYUE, WANG GONGSHAN, TANG WEIFONG

1988, 6(1):  6-11. 

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Telechelic polymers are synthesized via bi-functional living polymerization Initiated mainly by the adduct of sec-butyl lithium and m-diisopropenylbenzene. On the basis of the nonsteady state theory of kinetics of anionic polymerization, a method is established, with which the molecular weight distribution and other molecular parameters of the resultant polymer can be calculated from the reaction condition. Several examples of numerical computation are given, the data tabulated and the curves drawn illustrat the relationship between the molecular parameters and monomer conversion.

ON POLYMERIZATION KINETICS AND CHARACTERISTICSOF N-VINYL PYRROLIDONE AND METHYLMETHACRYLATE BY FTIR

RUAN ZHU, SUN YISHI, FU ZENGLI

1988, 6(1):  12-17. 

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The copolymerization process of a definite composition of N-vinyl pyrrolidone and methyl methacrylate was tracked by Fourier Transfer Infrared Spectrometer at different temperatures and different concentrations of crosslinking agent and initiator. The copolymerization kinetics and characteristics were studied. A reliable information for optimizing copolymerization technology is presented. The cause of improving transparency of the formed copolymer by adding a small amount of crosslinking agent was discussed.

KALESKI BUSINESS CYCLE MODEL AND ITS REFORM

FAN CHONGHUI, ZHANG YIMIN

1988, 6(1):  18-25. 

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Introducing investment decision equation to improve dynamic behaviour 19 proposed by authors^[1]. Based on the proposal, we discuss the necessity of further reform of Kaleski business cycle in order that the result of theoretical analysis coincides with the actual expanded reproduction process of capitalism. We also study the measures of improving dynamic behaviour of the model. In the analysis of discrete system with time delay, Z-transform is utilized, some numerical examples calculated, and the trouble caused by solving transcendental equation is avoided. As the order of characteristic equation becomes higher, the method proposed in this paper shows better its advantages. And microcomputers are found to be the suitable tools for researching dynamic problems. The wrong theoreticle solution of Kaleski model is found out and corrected in this paper.

OBSERVATION AND ANALYSIS OF THE NOISE DUE TO BIREFRINGENCE MODULATI ON IN FIBER-OPTIC GYROSCOPE

PENG GANGDING, HUANG SHANGYUAN, LIN ZONGQI

1988, 6(1):  26-31. 

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The noise due to the birefringence modulation of a nonideal phase modulator in a fiber-optic gyroscope is investigated. It is found that this noise contributes largely to long term bias drift of the system, and that the phase of this noise has a definite π/2 relation with that of the rotation signal. Theoretical analysis based on the Jones Matrix representation coincides quite well with the experimental results. Measures to reduce the birefringence modulation noise are discussed.

ON A FORMAL SOLUTION OF DUAL INTEGRAL EQUATION SYSTEM IN MEASUREMENT OF SEMICONDUCTORS

DAI XIANXI, WANG CHANGPING, LI HONGPANG, HUANG JINGYI

1988, 6(1):  32-39. 

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In this paper a dual integral equation system in the measurement of semiconductors is suggested. The system is decoupled to be an equation of double integral by an integral transformation.
According to Schlömilch theorem, the 2-dimensional problem is reduced to be a one dimensional Fredholm equation. An exact formal solution is obtained and a criterion is suggested to prove the uniqueness of the formal solution. In addition, the relation between the current and transformation function and explicit expression of solution for small r₀ are also derived.

A STUDY ON MICROWAVE APEXCARDIOGRAPHY

BEI TIANZHEN, ZHUANG GENSHEN

1988, 6(1):  40-43. 

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A microwave technique for recording apexcardiograms is reported. A microwave epexcardiography can detect changes in reflected microwaves caused by movement of the chest wall in response to left-ventricle activity. It has the unique advantage of not requiring any mechanical contact with the subject. Results show that microwave technique is useful for delineating the tine structure in the precordial movement and checking up the heart disease.

CURVE RESOLUTION FOR X-RAY PHOTOELECTRON CORE LEVEL SPECTRA

XU ZHIZHONG

1988, 6(1):  44-48. 

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The non-linear least square algorithm proposed by Brown and Dennis has been applied to the procedure of curve resolution for the X-ray photoelectron core level spectra, and satisfying result has been obtained. Some examples performed with this method are shown in this article.

AES XPS AND UPS STUDIES OF THE INTERREACTION OF OXYGEN AND IMPREGNATED DISPENSER CATHODES

CHEN DESEN

1988, 6(1):  49-54. 

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We have performed AES, XPS and UPS measurements of Type S and Type M tungsten dispenser cathodes as well as a model surface consisting of a barium monolayer on a tungsten strip in various stages of oxidation. The results indicate the presence of considerable difference between the Type S and Type M cathodes. It was found that Type M cathode is Ba-O-W system, while Type S cathode seems to be partial barium and partial barium oxide and oxygen coadsobed on tungsten. The oxygen may induce change of chemical state of surface barium and substrate tungsten, and change work function and emissive ability of cathodes. The barium layer in Type M cathode appears to be more insensitive to oxidation as indicated by core level changes tham that in the Type S cathode. The valence band structure is also less sensitive to oxygen than Type S cathode. The tungsten related features are more sensitive to oxygen compared to osmium.

THE STUDY ON EXTINCTION SPECTRA DUE TC PRECIPITATES IN Hg_1-xCd_xTe BY Mie SCATTERING

QIAN DINGRONG

1988, 6(1):  55-61. 

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Complex dielectrical constants have been calculated for Te, HgTe and Hg_1-xCd_xTe according to the classical theory. The aerosol model has been applied to take into account the extinction of light due to the precipitates of Te and HgTe in Hg_1-xCd_xTe, and the extinction spectra resulted from the precipitates with different radii have then been evaluated using Mie scattering theory.

A STRICT CALCULATION OF THE DEPTHDISTRIBUTION FUNCTION ϕ(ρz) OF X-RAY BY MONTECARLO SIMULATION

HE YANCAI, CAO LIQUN, CHEN JIAGUANG

1988, 6(1):  62-66. 

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The differences of the electron scatterings in various solids were considered in claculating X-ray distribution functions in isolated films using Monte Carlo simulation. The integrated values of the forty common elements are given in this paper.

THE EXTREME VALUE CONTROLLING BY DERIVATIONWITH RESPECT TO TIME AND ITS APPLICATIONTO X-RAY DIFFRACTION TOPOGRAPHY

LU ZHIPING

1988, 6(1):  67-73. 

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The automatic following system of Bragg angle was set up in terms of the extreme value controlling by derivation with respect to time. The relative errors are within ±0.05. We performed some experiments in X-ray topography of sapphire and synthetic quartz and obtained quite good results.

THE EFFECT OF SUBSTRATE ORIENTED ON SiGROWTH RATE IN CVD PROCESS BY SILANE PYROLYSIS

ZHANG XIKANG, GU LONGDAO

1988, 6(1):  74-77. 

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In CVD process by silane pyrolysis, the growth rates of silicon are independent on the orientation and material of substrates. Identical activation energy for growth is obtained for different orientations. It is believed that the silicon growth is carried out by the diffusion of the homogeneous reaction products towards the substrate and the accumulation on it.

INTERFACIAL REACTIONS AND CHARACTERISTICS OF Pt-Si SYSTEM COMPLEX ELECTRODES

LI SIYUAN, JIA XIAOTIAN, LI SHOUSONG, SHEN MINGZHI, YIN ZHIPING

1988, 6(1):  78-85. 

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In this paper, interfacial reactions and characteristics of multi-layer metal filmson silicon surface such as Al-Ti-Pt-Si, Al-Mo-Pt-Si, Al-Ti-Si etc. are studied systematically. The results of electron spectroscopy analyses, scanning electron microscope and electrical methods of the layered structures are presented, and action mechanisms of these interface effects are discussed.

A HIGH RESOLUTION TeO₂ ACOUSTO-OPTIC DEFLECTOR FOR RAD IO SPECTRAL ANALYSIS

HUANG GENGCHEN, ZHAO GUOZHBN, WANG JINGSHENG

1988, 6(1):  86-90. 

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A high resolution TeO₂ acousto-optical deflector for radio spectral analysis was designed and manufactured according to the principle of off-axis abnormal Bragg diffraction. The theoretical resolution is 19kHz, while in practice, a resolution of 28.5kHz was achieved. The 1dB bandwidth is 22MHz. The deflection is a linear function of input power up to 100mW. An acousto-optical spectrograph with TeO₂ deflector was constructed and an excellent result in the observation of dark cloud was obtained.

NEW EMISSION INFRARED BAND (b³∑_g⁺-x³∑_u⁺) IN ALKALI VAPOR OF Li

LU YIQUN

1988, 6(1):  91-94. 

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When we used an overtone (257.25nm) of Ar-Laser (514.5nm) and 457.9nm to pump Li-vapor, we observed a new emission band in Li-vapor. It is believed that the band between lμm to 1.4μm is attributed to the Li₂(b³∑_g⁺)-Li₂(x³∑u⁺) transition.