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Volume 2 Issue 8
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Original Articles
RADIATION EFFECT OF BISMUTH GERMANATE INDUCED BY FAST NEUTRONS
GU Yi-fan, HE Jing-tang, SUN Yue, WANG Mao-zi, YANG Qing-yun, ZHU Guo-yi
Chin. Phys. Lett. 1985, 2 (8): 337-340 .  
Abstract   PDF(pc) (55KB) ( 449 )
The radiation effect of bismuth germanate induced by 14MeV neutrons has been studied by using techniques of nuclear radiation detection. Substantial changes, pulse height as well as in energy resolution of the 137Cs photopeak followed by spontaneous recovery were observed and measured after irradiation. The radioactivities observed along with the above radiation damage have been carefully analyzed and identified with these from neutron activation.
GROWN-IN DEFECTS IN NATURAL BERYLS BY X-RAY TOPOGRAPHY AND BIREFRINGENCE
JIANG Shu-sheng, LI Qi
Chin. Phys. Lett. 1985, 2 (8): 341-344 .  
Abstract   PDF(pc) (119KB) ( 339 )
The growth sectors and their boundaries, impurity zonings and dislocations in natural beryls hare been observed by means of X-ray diffraction topography and birefringence. The displacements of fault surfaces of the sector boundaries are perpendicular to the fault surfaces. The Burgers vectors of some typical dislocations in (0001) sector are <1120>, <1100> and <1450>. It is found that the techniques of X-ray diffraction topography and optical birefringence are complementary.

THE ELIMINATION OF In ISLANDS ON InP SURFACES AND ITS MECHANISM
JIN Xiao-feng, YU Ming-ren, WANG Xun
Chin. Phys. Lett. 1985, 2 (8): 345-348 .  
Abstract   PDF(pc) (50KB) ( 363 )
The surface indium islands originated by argon ion bombardment can be removed by evaporating phosphorous on InP surface followed by annealing. A possible mechanism of elimination of In islands is proposed based on the experimental ELS and XPS data.
LOW TEMPERATURE MAGNETIC PROPERTIES OF Nd2Fe14B SINGLE CRYSTAL
WANG Yi-zhong, WANG Zhen-xi, GONG Wei, FENG Min-ying
Chin. Phys. Lett. 1985, 2 (8): 349-352 .  
Abstract   PDF(pc) (40KB) ( 371 )
Magnetic anomaly was observed in Nd2Fe14B single crystal below 150K. Temperature dependences of magneto-crystalline anisotropy constants K1 and K2 has been studied. Such anomaly observed in Nd2Fe14B can be interpreted by temperature dependences of anisotropy constants K1 and K2.
CONCENTRATED SUSPENSION THEORY OF SOUND ATTENUATION IN MARINE SEDIMENTS
QIAN ZU-wen
Chin. Phys. Lett. 1985, 2 (8): 353-356 .  
Abstract   PDF(pc) (45KB) ( 428 )
Taking the sound interaction among particles in concentrated suspension into account and supposing that the masses of them have a normal distribution over the phi values of granular diameter, the statistical averages of scattered radiation and absorption coefficients in sea-bottom sediments are obtained. It is shown by numerical results of this paper that there will be a linear dependence of absorption coefficient on frequency as long as there is a large deviation of granular diameter. However, if βR ≤ 1, where R is the size of grains and β is the wavenumber of viscous wave, then the attenuation will vary with the frequency to the power higher than one.


A MODEL OF INTERDIFFUSION IN COMPOSITIONALLY MODULATED ALLOYS
XIONG Shi-jie
Chin. Phys. Lett. 1985, 2 (8): 357-360 .  
Abstract   PDF(pc) (51KB) ( 405 )
We propose a model to describe the microscopic processes of interdiffusion in compositionally modulated alloys, taking into account not only the short range interaction between the migrating atoms and their environments, but also the long range Coulomb's forces arising from the charge transfer due to modulation. The results for relations between the interdiffusivities and the modulation wavelengths, obtained by neglecting the correlation effect, show the behaviour observed in experimental works.

A STUDY OF THE W(011) SURFACE BY TWO-DIMENSIONAL LATTICE EFFECTIVE HAMILTONIAN
HU Gen-you
Chin. Phys. Lett. 1985, 2 (8): 361-364 .  
Abstract   PDF(pc) (46KB) ( 367 )
The W(011) surface is studied with a two-dimensional lattice effective Hamiltonian which provides an accurate description of the zero temperature phase diagram and critical fluctuation properties of the structural phase transitions of W(011). At T=0, the reconstructed W(011) is found to be uniquely P(2x1) structure, A theoretical model is given which can explain many experiments satisfactorily.




A NEW WEAK ITINERANT FERROMAGNET Fe2N
CHEN Guan-mian, LI Jing-yuan
Chin. Phys. Lett. 1985, 2 (8): 365-368 .  
Abstract   PDF(pc) (58KB) ( 340 )
Fe2N has been identified as a new weak itinerant ferromagnet by magnetic measurements. It has the highest ratio qc/qs of effective atomic moment qc to the atomic moment qs, and a low Curie temperature Tc = 7K. The magnetic properties were analysed according to the Stoner-Edwards-Wohlfarth (SEW) model, which give results, in agreement with the magnetization and susceptibility measured at temperatures below Tc.


NONLINEAR OPTICAL PHASE CONJUGATE EFFECT CAUSED BY F-2 COLOR CENTER IN LiF CRYSTALS
ZHANG Tao, WAN Liang-feng, RUAN Yong-feng
Chin. Phys. Lett. 1985, 2 (8): 369-372 .  
Abstract   PDF(pc) (39KB) ( 499 )
We report the experimental observation of nonlinear optical phase conjugate (NOPC) effect caused by the resonant saturable absorption of F-2 centers in LiF crystals. The experiment was performed by making use of degenerate four-wave mixing in the laser cavity. We also give the curve of the phase conjugate reflectivity versus the incident energy of the probe light.

SUPERFLUORESCENCE CAUSED BY COLLISIONS BETWEEN EXCITED Mg ATOMS
ZHANG Dao-zhong, CHENG Bing-ying, JU Rui, ZHAO Xiao-kang
Chin. Phys. Lett. 1985, 2 (8): 373-376 .  
Abstract   PDF(pc) (44KB) ( 412 )
when 3s3p(1p) of Mg is resonantly excited by a dye laser, the bright and directional emission at 5184Å can be observed. We have measured its intensity and temporal behavior in different Mg density. This emission is believed to be the superfluorescence, whose upper level is populated by inelastic collisions between excited Mg atoms.
STUDIES OF WC CATALYSIS
LIN Zhang-da, WANG Chang-heng, SHEN Dian-hong
Chin. Phys. Lett. 1985, 2 (8): 377-380 .  
Abstract   PDF(pc) (67KB) ( 400 )
UPS and XPS was used to measure the electronic structure of WC, Pt and W. Magnetic susceptibilities of WC and W from 1.5K to 300K have been measured. The experimental results can be explained as follows: the similarity of catalytic activity between WC and Pt originates mainly from the existence of nonbonding electrons in both materials.

ROCKING CURVE CALCULATION BY MEANS OF CHANGING INVOLVED DIFFRACTION BEAMS
LIU Da, WANG REN-hui
Chin. Phys. Lett. 1985, 2 (8): 381-383 .  
Abstract   PDF(pc) (42KB) ( 363 )
By changing the diffraction beams involved in rocking curve calculation with matrix method, according to the incident beam direction, the required computing time may be considerably reduced.
12 articles