Search

Article

x

Vol. 29, No. 12 (1980)

1980-06-20
CONTENT
COMPOSITE LATTICE OF TWO PHASES WITH A COINCI-DENCE SITE LATTICE RELATIONSHIP (Ⅰ)——COINCIDENCE SITE LATTICE
YANG QI-BING
1980, 172 (12): 1517-1525. doi: 10.7498/aps.29.1517
Abstract +
Two new methods to find the basic vector correspondence matrix of the coincidence site lattice for two phases have been developed by means of theory of matrix and elementary theory of numbers. Based on these methods the three equations which are applied to find a coincidence site lattice have been incoporated into a single one so that the problems concerning the composite lattice of two phases with a coincidence site lattice relationship are greatly simplified. It has been verified that the whole of selfcoincidence problems in the cubic system, the most of self-coincidence problems in non-cubic systems and a part of inter-coincidence problems can be simplified by the incorporating of discriminant equations.
COMPOSITE LATTICE OF TWO PHASES WITH A COINCI-DENCE SITE LATTICE RELATIONSHIP (Ⅱ)——COINCIDENCE COEFFICIENTS OF SPACE LATTICES AND PLANE LATTICES
YANG QI-BING
1980, 172 (12): 1526-1534. doi: 10.7498/aps.29.1526
Abstract +
Universal and straight-forward formulas for finding coincidence coefficients of space lattices of two phases and their plane lattices having a coincidence site lattice relationship are derived by means of elementary theory of numbers. The coincidence coefficient of a space lattice is α2(3)=1/|C(1)| and that of their plane lattices are α2(h)= (H(2)C(1)/|C(1)|, C(1) being a basic vector correspondence matrix of CSL, and H(2)= [h1(2)h2(2)h3(2)]. In case C(1) is unknown, coincidence coefficients of a space lattice and their plane lattices can be found through the basic vector correspondence matrix φ of two phases and coincidence coefficient matrix C then α23= k1(2)k2(2)/d3, α2(h)=(CH(2),dk1(2))/d2. To find matrix C is much easier than to find C(1).
A STUDY OF INTERNAL FRICTION ASSOCIATED WITH THE MARTENSITE TRANSFORMATION AT LOW FREQUENCY
WANG YE-NING, ZHOU YI-FENG, ZHANG ZHI-FANG
1980, 172 (12): 1535-1544. doi: 10.7498/aps.29.1535
Abstract +
The internal friction peak associated with the process of martensite and reverse martensite transformation in Au-Cd alloy were measured by torsion pendulum. There is a linear relation between the peak value and rate of heating. The stable peak (heating rate=0) is much higher than that of Fe-Mn alloy and the internal friction value is independent of frequency which is characteristic of static hysteresis loss. The height of the internal friction peak is related to the grain size of Martensites. There also appears a peak during the process of isothermal martensite transition According to these experimental results, we attributed this internal friction induced by martensite transition to those movable coherent interface under the action of vibrating stress.
A PHASE DIAGRAM OF THE ALLOYS OF THE TERNARY SYSTEM OF THE ALUMINIUM-COPPER-GALLIUM
PAN YU-YING, ZHENG JIAN-XUAN
1980, 172 (12): 1545-1550. doi: 10.7498/aps.29.1545
Abstract +
A phase diagram of the alloys of the Al-Cu-Ga ternary system has been determined by using X-ray analysis.The isothermal section at room temperature was found to consist of eleven single-phase regions (i.e. α, γ2, γ′, δ, ζ1, ζ2, η2, θ, θ′,αA1 and Ga), fourteen two-phase regions (i. e.α + ζ1, α+ γ2, α + γ′, γ2 + γ′, γ′+ ζ1, γ2+δ, γ′+δ,δ +ζ2, ζ2+η2, η2+θ,η2+ θ′, γ′ + θ′, θ′+ Ga, and θ + αA1); and nine three-phase regions (i. e. α + γ′+ζ1, α+ γ2+ γ′, γ2+ γ′ + δ,γ′ + δ + θ′, δ+ζ2+θ′, ζ2 + η2 + θ′, η2+ θ′ + Ga, η2 +θ + Ga and θ + Ga + αA1). No new phase has been observed in this system.
A NEW GRAPHIC METHOD OF INDEXING DEBYE-SCHERRER PHOTOGRAPHS
LU XUE-SHAN
1980, 172 (12): 1551-1557. doi: 10.7498/aps.29.1551
Abstract +
A new graphic method has been developed for indexing Debye-Scherrer photographs, Utilizing the sin2θ values of three low angle reflexions and the density of the crystal investigated, a series of conditional lines and equiatomic curves are drawn in the A-C space, where A=λ2/4α and C=λ2/4C2 in the tetragonal system, and A=λ2/3a2 and C=λ2/4c2 in the hexagonal system. The conditional lines are a manifold of straight lines representing the general equation miA + niC - sin2θi=0, the intercepts of which on the coordinate axes A and C being xi= sin2θi/mi and yi = sin2θi/ni, where mi= hi2+ ki2, ni = 1i2 in the tetragonal system, and mi = hi2+ hiki + ki2, ni = 1i2 in the hexagonal system. Three manifolds of conditional lines representing respectively three different sin2θi's are drawn in three different colours.The equiatomic curves are represented by the general equation A2C=Kz, where Kz= (1/64) (ρλ3/Mm0)2(1/Z2) for the tetragonal system, and Kz= (1/48)(ρλ3/Mm0)2 (1/Z2) for the hexagonal system, containing Z as a parameter. In each equation, ρ is the density, M is the atomic weight or the formula weight of the crystal, and m0 is the mass of the atom of unit atomic weight. These curves are drawn in black, indicating in each case an integral number of atoms or configuration units contained in the unit cell.The interception of three conditional lines drawn in three different colours, which passes through one of the equiatomic curves, thus determines uniquely the dimension of the unit cell and the number of atoms or configuration units contained therein.This method may be applied to the tetragonal as well as to the hexagonal system. The cubic system may be considered as a special case of the tetragonal system.
CRYSTAL GROWTH OF Y3-xBixFe5O12
XU XIAO-ZHEN, JIA WEI-YI, LIU CHAO-XIN
1980, 172 (12): 1558-1563. doi: 10.7498/aps.29.1558
Abstract +
The pseudo quaternary system phase diagram of Y2O3-Fe2O3-Bi2O3-PbO·0.2B2O3 is obtained and used. Single crystals of the ferrimagnetic garnet Y3-xBixFe5O12(O≤x≤ 1.2) are grown by using Bi2O3-PbO-B2O3 flux systems. The dependences of the content Bi (x) in the single crystals of Bi-YIG on the compositions of the solutions arediscussed.
A CLOSED-FORM APPROXIMATION FOR THE 3-DIMENSIONAL ISING MODEL (Ⅱ)——LIMITATIONS OF THE Q-APPROXIMATION
SHI HE, HAO BAI-LIN
1980, 172 (12): 1564-1569. doi: 10.7498/aps.29.1564
Abstract +
We present an analysis of further physical consequences of the Q-approximation and a discussion on the number of closed paths taken into account by this method. A counter example ("Incense" graph in Fig. 3) shows there exists no rotation angle mapping which would give the proper number of closed paths on a 3-dimensional lattice.
SCATTERING OF LASER BEAM BY DIFFUSING SURFACES (Ⅱ)
CHENG LU, ZHANG BING-QUAN
1980, 172 (12): 1570-1580. doi: 10.7498/aps.29.1570
Abstract +
Several principal conclusions for the so-called core-wing-ratio method for measuring the roughness of diffusing surfaces with laser beam based upon the previous papers are given. The method for determining the coefficients in the probability density function P(h) of random height is given, following the emperical relation R2=5Ra. For P1(h)={e(-b(|h|/hm)) ,|h|≤hm 0,|h|>hm and P2(h)=e(-a2(h/hm)2) is determined that b=1.23 and a2=2. It is shown that in both P1(h) and P2(h), hm is corresponding to 1/2Rz. The core-wing-ratio values D2/D1 as functions of Rz are deduced and computed for P1(h) and P2(h) with formulas which are more precise than that in the previous papers. In addition, the relation of the half width of the core of diffraction pattern with Rz is computed, and it is pointed out that the half-width method is not convenient for surface roughness measurement.
THE GENERATION OF FAR-INFRARED RADIATION BY DIF-FERENCE-FREQUENCY MIXING OF SURFACE WAVES
HUO CHONG-RU, HUANG XI-YI
1980, 172 (12): 1581-1587. doi: 10.7498/aps.29.1581
Abstract +
It is suggested that far-infrared radiation can be generated by difference-frequency mixing of surface waves on an interface between metal and nonlinear crystal. Particularly, the power of FIR generated on Al-GaAs interface is catculated in the case of noncollinear phase matching. In this calculation, the imaginary part of dielectric constants is considered.
A NEW PRINCIPLE FOR LASER TUNING——TUNING BY SELF-INJECTION
XU ZU-YAN, PAN SHAO-HUA, DENG DAO-QUN, GUO DONG-SHENG, LI XIU-FANG
1980, 172 (12): 1588-1595. doi: 10.7498/aps.29.1588
Abstract +
We suggest a new efficient method of laser tuning: the principle of tuning and amplification by self-injection. By this means, the influence of tuning elements on the laser output power is reduced to a minimum, that is, the tuning efficiency can approach 1. This provides a possibility for laser outputs of both high power and narrow bandwidth to be obtained with one laser oscillator. The theoretical and experimental results are given.
CHLORINE CHEMISORPTION ON THE SILICON AND GERMANIUM SURFACE
ZHANG KAI-MING, YE LING
1980, 172 (12): 1596-1603. doi: 10.7498/aps.29.1596
Abstract +
The chlorine chemisorption geometry fcr both Si(lll) and Ge(lll) surface is considered. Previous theoretical calculations could not give the difference between Cl chemisorbtion on Si (111) and Ge(lll), which was shown by the effects observed in the photoemission with polarized radiation. In this paper the chemisorbed site is determined by the minimization of the total energy calculated by the charge density selfconsistent extended Huckel method. The present calculation shows that Cl adsorbs on the top site of Si (111) surface with covalent binding, which agrees quite well with experiments. While for the case of Ge, calculation shows that both the top site and three-fold site of Cl ehemisorption on the Ge(lll) surface are possible. Since the photoemission by p-polarized and s-polarized radiation did not differ too much for Cl on the Ge(lll) surface, it can not rule out the possibility of top adsorbed site for
BRIEF REPORT
THE HARRIS SINGULARITY OF THE JOSEPHSON CURRENT OF A JUNCTION DRIVEN INTO NON-EQUILIBRIUM
MAO DE-QIANG, GU YI-MING, ZHOU ZI-FANG, WU HANG-SHENG
1980, 172 (12): 1604-1607. doi: 10.7498/aps.29.1604
Abstract +
Based on the OS model, the Harris singularity of the Josephson current of a junction which is driven into non-equilibrium, is investigated.
THE CACULATION OF INTENSITY DISTRIBUTION FOR THE INTERFERENCE PATTERN OF DIFFUSED LIGHT
ZHAN DA-SAN
1980, 172 (12): 1608-1612. doi: 10.7498/aps.29.1608
Abstract +
In this article, the Fresnel-Kirchhoff diffraction formula is used to study the interference phenomena described previously in [1]. The expression for intensity distribution of the interference pattern is derived and the maximun positions obtained. A physical interpretation of the interference phenomena is given.
THE CHEMISORPTION OF AI ON THE GaAs(110) SURFACE
ZHANG KAI-MING, YE LING
1980, 172 (12): 1613-1616. doi: 10.7498/aps.29.1613
Abstract +
The chemisorption of Al on the GaAs(ll0) surface is studied by using the charge self-consistent EHMO method. In comparing the two different mechanisms of adsorption, the more stable mechanism is determined by the configuration which gives a lower energy, and it is suggested from the present study that Al will substitute the surface Ga atoms, while the latter will be adsorbed on the dangling bonds of the surface As atoms. The charge transfer, the bond strengths and the density of states are also considered.
THE HAWKING EVAPORATION OF DIRAC PARTICIES
Xu Dian-yan, Liu Liao
1980, 172 (12): 1617-1624. doi: 10.7498/aps.29.1617
Abstract +
The problem of solving the Dirac equation in a Kerr space-time has long been unresolved. In 1976, S. Chandrasekhar solved the decoupling problem of the Dirac equation with non-zero rest mass in a Kerr background, thus provided the possibility of attacking the problem of the Hawking evaporation of Dirac particles. In this paper, starting from Chandrasekhar's results, we find the solution of the Dirac equation with non-zero rest mass just out side the event horizon of a nearly extreme Kerr black hole and sucessfully derived the Hawking thermal formula.
CALCULATIONS OF HUGONIOT CURVES FOR FIVE SIMPLE METALS WITH PSEUDOPOTENTIAL METHOD
LI SHU-SHAN, LIN GUANG-HAI
1980, 172 (12): 1625-1628. doi: 10.7498/aps.29.1625
Abstract +
On the basis of the pressure Px at 0 K deduced by the present authors in the paper [1], using Debye solid model and considering the thermal pressure of electrons, we obtain the equation of state for metals at high temperature and pressure. Combining this equation with Hugoniot equation we can calculate the Hugoniot curves which can be compared with experimental data. The Hugoniot curves for five simple metals (Na, K, Mg, Al and Pb) are calculated. The comparison between theory and experiments shows that the theoretical calculations are all in fairly good agreement with the experiments when the pressure is below 500 kbar for Na and K, 1.7 Mbar for Mg, 4.9 Mbar for Al and 34 Mbar for Pb.
THE STUDY OF SHG IN THE POLYDOMAIN STRIAE REGION OF LiNbO3 SINGLE CRYSTAL
WANG YE-NING, CHU JING-SUNG, TAN YUN-PENG
1980, 172 (12): 1629-1635. doi: 10.7498/aps.29.1629
Abstract +
Using acousto-optic Q-switched Nd3+: YAG laser as a source of fundamental beam, we measured the SHG scan vs temperature in LiNbO3 and BNN single crystals. There are usually two peaks appearing on the SHG scan curves for the striae region, at the same time two NPM hollow cones of SHG light may be observed in one to one correspondence.One of the two peaks in the polydomain striae region of LiNbO3 disappeared after the crystal was completely polarized. The occurrence of this peak was analyzed.The SHG power in the polydomain region of LiNbO3 is usually several times larger than that of single domain region. We attributed the enhancement mechanism to the stress relaxation occurring with the formation of insular 180°domains.
OBSERVATION OF DISLOCATIONS AND SUBBOUNDARIES IN OPTICALLY ACTIVE CRYSTAL Bi12GeO20 BY MEANS OF REFLECTION BIREFRINGENCE TOPOGRAPHY
XU XIU-YING, FENG DUAN
1980, 172 (12): 1636-1639. doi: 10.7498/aps.29.1636
Abstract +
In this paper, we studied the birefringence topography of bismuth germaniun oxide which hare a strong natural optical activity. It is discovered that the natural optical activity of the crystal may be compensated completely with a reflection polarised light microscopy so that the birefringence images of dislocations and subboundries were observed. The Burgers vectors of dislocations were found to be of the type of 1/2 ( 111), (100) and (110).
AN X-RAY METHOD OF DETERMINING THE DEGREE OF PREFERRED ORIENTATION OF FERROELECTRIC MATERIAL WITH LAYER TYPE STRUCTURE AFTER HOT-PRESSING
GUO CHANG-LIN, WU YU-QIN
1980, 172 (12): 1640-1644. doi: 10.7498/aps.29.1640
Abstract +
The definition and an X-ray determination method of the degee of preferred orientation of ferroelectric ceramics with layer type structure after hot-pressing procedure are presented. The degree of preferred orientation can be obtained by merely determining the ratio of diffraction intensity of any one or more (00l) lines before and after hot-pressing procedure. Taking the mixed bismuth oxide compound with layer type structure PbBi4Ti4O15 as an example the suitability of this method has been proved.
INFLUENCE OF THE TRANSMISSION LIGHT OF α-LiIO3 SINGLE CRYSTAL BY THE APPLICATION OF AN ELECTROSTATIC FIELD
WANG XIU, LUO GUI-YUN
1980, 172 (12): 1645-1648. doi: 10.7498/aps.29.1645
Abstract +
An electrostatic field is applied along the s-axis of a-LiIO3 single crystal. Let a beam of light pass through the crystal along the direction of the crystal 2-axis, almost no change of the transmission photograph is found; when the beam of light passing through the crystal deviates from the direction of the crystal z-axis, some patterns appear on the transmission photograph. In this work, the special frequency spactrum analysis and microscopic observation and the light diffraction experiment had been carried out.