Vol. 31, No. 5 (1982)
COMPUTER SIMULATIONS OF THE ANOMALOUS INTERNAL FRICTION ASSOCIATED WITH THE INTERACTION BETWEEN OSCILLATING KINKS AND MOBILE POINT DEFECTS
1982, 31 (5): 561-570. doi: 10.7498/aps.31.561
Based on a simplified potential of a solute atom in the dilatation field of a kink, the general one-dimensional diffusion equation of solute atoms along the pipe of a dislocation with a moving kink was solved numerically. The instantaneous distribution of the concentration of solute atoms, instantaneous values of the dissipation of energy, of the mean damping coefficient and of the mean rigidity of an oscillating kink were calculated.Simplified approximate formulae about the mean damping coefficient and the mean rigidity were deduced from the numerical results obtained previously and in this paper, in terms of which the anomalous internal friction phenomena were explained semi-quantitatively.
Huanghoite fBaGe(CO3)F] is a new mineral discovered in China. The parameters of the hexagonal unit cell have been determined as α=5.07?, c=38.6? by using electron diffraction method. The value of c is twice as large as that determined previously by X-ray diffraction analysis. Huanghoite is composed of atoms with large difference in atomic number. The advantage of electron diffraction in investigating such kind of minerals is discussed.The stacking faults along direction c have been observed by lattice imaging technique. The possille cause of formation of such faults is proposed.
Huanghoite, BaCe [Fl(CO3)2], a new mineral from China, is a kind of carbonate containing Ba, Ce, F. It belongs to trigonal system. The intensity data are collected with the aid of fully automatic four-circle X-ray diffractometer. The lattice parameters are α=b=5.070(±0.003?), c=38.408(±0.005?); space group is R3m; z=6. More exact determination has been made on the basis of earlier worke, giving the final R=0.041.The relation between superstructure and pseudo-structure of this crystal has been analysed. We compared our results with that of earlier works. Suggestion is made for the correction for similar minerals. Finally, the individual experimental data are discussed.
1982, 31 (5): 585-603. doi: 10.7498/aps.31.585
A model of radiation by multi-atoms is discussed. System A, composed of N atoms with two energy levels, is coupled with a single-mode radiation B. A and B are in turn coupled with two thermal reservoirs D and C respectively, and we also assume that all atoms which are located within a wave length of the radiation field have the same phase. Then under the approximation of long wave, rotating wave and mean fields, by introducing Markov approximation after using the method of density matrix, we have derived the of equations motion for systems A and B respectively. These equations are concerning with the following processes: the spontaneous emission of single atom, the absorption and induced emission stimulated by thermal radiation, the induced emission of N atoms stimulated by single mode coherent state radiation as well as the coherent spontaneous emission of this multi-atoms system. The latter two processes are actually the two kinds of superradiance originated from Dicke model and had been investigated previonsly. We have analysed these five processes by numerical calculations. Besides, the influence of these processes upon the evolution of atomic system attaining thermal equilibrium and the increase of entropy is also discussed. It is pointed out that the correlations inside a multi-atoms system would not be destroyed by coherent spontaneous emission, in contrast with the incoherent one which leads to the change of entropy in atomic system. However, only when the entropy of the two reservoirs has been taken into account, will it be possible to demonstrate the mono-tonic increase in total entropy.
ON THE RELATIVISTIC ABERRATION THEORY OF A COMBINED FOCUSING-DEFLECTION SYSTEM WITH MULTI-STAGE DEFLECTORS
1982, 31 (5): 604-614. doi: 10.7498/aps.31.604
In the present paper, the relativistic first order chromatic and third order geometrical aberration formulas, which are different from those in ref. , have been derived for a combined focusing-deflection system with superimposed field, and all aberration coefficients have been given in explicit form. With the help of these aberration formulas, the deflection aberrations of a combined system with multi-stage deflectors have been discussed in detail.
1982, 31 (5): 615-622. doi: 10.7498/aps.31.615
The strong quasi-elastic scattering of light observed with a laser beam transmitting through an α-LiIO3 single crystal under the action of a DC field in the c-direction was further investigated. we recognized that the phenomenon consists of the following: (1) A scattering band appears perpendicular to the c-axis and extends to very large scattering angles. The scattered beam is the ordinary light, if the incident beam is the extraordinary light; and vice versa. If the incident beam contains both the ordinary and extraordinary components, two bands may be observed slightly separated in the azimuthal direction. (2) A band extends in the same direction as (1), but the polarization state does not change after scattering. (3) The scattered beam produces a pattern with one or a number of stripes in tilted directions other than those of c-axis. Their spatial frequency spectra are rather limited and the polarization state does not change. For all the three types of scattering we recorded the fine structure of intensity distribution vs the scattering angle, the relaxation of light scattering after the DC potential having been removed and the variation of the scattered intensity with the change of the locality through which the incident beam passes. Because of the behavior of unidimensional ionic conduction in α-LilO3, it is possible to prepare a specimen such that in a certain part of its volume the field is strong but no current flows. We noticed that no scattering occurs when the light passes through only such a space in a specimen. The strength of scattering is apparently associated with the current density. The scattering (1)-(3) may be interpreted as a radiation process of second order, phenomenologically described by the time and space fluctuation of the diagonal and nondiagonal components of the dielectric tensor. They are originated from the distribution and redistribution of the space charge. The nondiagonal components are now not zero even referred to the principal axes of the crystal. The fine structure of scattered intensity and related features should be attributed to the decoration of quasiperiodical defects.
THE STUDIES OF PHASE DIAGRAM AND CRYSTALLIZATION KINETICS OF AN AMORPHOUS STATE IN THE PSEUDO-BINARY SYSTEM LiIO3-NaIO3
1982, 31 (5): 623-632. doi: 10.7498/aps.31.623
The phase diagram, phase transition, and formation, stability and crystallization kinetics of amorphous state in the system LiIO3-NaIO3 have been investigated. The pesudo-binary system LiIO3-NaIO3 is a eutectic one, its eutectic reaction occurs at 325℃ and the composition at eutectic point is 50 m/o LiIO3. As the melt is quenched from a temperature 150℃ higher than the melting point, an amorphous state of iodate salts is obtained for the first time. The apparent transition temperature decreases when the amorphous state exists. It is found that some factors, such as intense X-ray irradiation, various humidity and fine grain size, make the crystallization speed of amorphous state increases. Crystallization speed and perfection of LiIO3 in the amorphous state is higher than NaIO3. The process of isothermal phase transition agrees with Johnson-Mehl-Avrami equation y(t) =l-exp(- btOn), when y = 0.1-0.9, where y is the quantity of crystallization. For the sample with composition of 60 m /o LiIO3, the Avrami time exponent n = 2-3 and rate constant parameter b increases exponentially with temperature. The activation energy of crystallization from amorphous state is found to be 2.21 eV.
1982, 31 (5): 633-645. doi: 10.7498/aps.31.633
This work is a continuation of the ref. [1, 2] and . The method developed in the previous works is extended to the study of a semi-infinite n-s multi-film structure. This structure is constructed as follows. First, we obtain a crystal thin film which may be either normal or superconducting by cutting a perfect infinite crystal at two separate paralled atomic planes. And then a mixed unit O composed of a thin film A and a thin film B is formed by close metallic contact. Finally, a semi-infinite multi-film structure is constructed by placing unit O's consecutively along the direction perpendicular to the interface. The corresponding single particle Green's functions for each step have been calculated. When film A and B belong to different normal metal, the results of the numerical calculation for both the single particle density of state and the energy band of such a structure have been given. When films A and B are made of the same normal metal, the results are equivelent to that of ref . Futher-more, the equations for the case that one of the thin films is superconducting have been derived. The numerical results show that 1) the whole n-s multi-film structure is superconducting, and a finite peak appears in single particle density of states near the original gap edge, 2) the whole structure is gapless just as expect.
1982, 31 (5): 646-653. doi: 10.7498/aps.31.646
A phosphorus implanted p-Si layer with dose slightly higher than its critical value was studied by EER combined with stripping-etching technique. The concept of a certain optimal wavelength, named "Specially Effective Wavelength" (SEW), is introduced for the optical measurements of structurally disordered materials. At SEW, the absorption coefficients of a material with different degree of disorder, from crystalline to amorphous, are all equal. For Si, the SEW is approximately 3490 ?, i. e. hω～3.55 eV (in the E1, E1 + △1 region), and the corresponding absorption coefficient is 106cm-1 independent of its degree of disorder. The depth profile of (△R/R)3.55ev is related to that of disorder degree, and the characteristic relations △R/R(D) were obtained for all of the three depth regions. The resulting curve for the implant-damaged region is similar to that reported by Anderson et al. for GaAs layers implanted with inert elements ions. By use of stripping, the observation of the disorder degree dependence of the 3.4 eV structure lineshapes has been realized in a wide range with only one sample. A comparison is made with the lineshape features of vacuum evaporated Ge films. Some conclusions have been drawn from these measurements about the mixed lattice interaction origin of the 3.4 eV spectral region of silion. It has been confirmed that EER is a powerful technique with extremely high sensitivity for the investigation of ion implanted semiconductor layers.
1982, 31 (5): 654-659. doi: 10.7498/aps.31.654
In evaluating the β-spectrum of atomic 3H, a more accurate formula is obtained, in which the first three transitions leading to the lowest three states of 3He+ are treated exactly, and the closure approximation is used to estimate the contribution from all excited states with n > 3. The formula thus obtained is compared with that used by Lyubimov et al. in determining the neutrino mass. As a result, it has been shown that the formula used by Lyubimov et al. does not yield an adequate accuracy. Especially the end-point energy they obtained may differ from the true value by 13.6 eV, which would cause an uncertainty of the same order in the value of the neutrino mass.
1982, 31 (5): 660-663. doi: 10.7498/aps.31.660
In this note, we developed a new functional evaluation method for effective potential in scalar QED. This evaluation method is more simple and feasible, but doesn't include more approximation than the previous methods.
THE DIRECT DETERMINATION OF STACKING FAULTS SEQUENCE IN ZnS POLYTYPE BY HIGH RESOLUTION ELECTRON MICROSCOPY
1982, 31 (5): 664-667. doi: 10.7498/aps.31.664
Lattice imaging with tilted illumination at the 3.12? level has been used for direct determination of stacking sequences in ZnS polytype by observing electron micrographs. The method employed is used to reveal the stacking sequences in the disordered and faulted ZnS.
1982, 31 (5): 668-673. doi: 10.7498/aps.31.668
The dysprosium-nickel phase diagram has been completed by X-rays in conjunction with differential thermal analysis. The intermetallic compound DyNi4 was detected, and the new intermetallic compound Dy4Ni17 was observed.In this system there exist ten intermetallic compounds: Dy3Ni,Dy3Ni2,DyNi,DyNi2,DyNi3,Dy2Ni7,DyNi4,Dy4Ni17,DyNi5, and Dy2Ni17. The intermetallic compounds DyNi and DyNi5 melt congruently at 1248℃and 1387℃, and the intermetallic compounds Dy3NiDy3Ni2,DyNi2,DyNi3,Dy2Ni7,DyNi4,Dy4Ni17 and Dy2Ni17 are formed by eight peritectic reactions at 762℃, 928℃, 1258℃, 1283℃, 1307℃, 1336℃, 1352℃ and 1321℃, respectively. Three eutectic reactions occur: at 31 at% Ni and 693℃, 56 at% Ni and 1173℃, 93 at% Ni and 1279℃. Neither Dy in Ni nor Ni in Dy shows any detectable solid solubility.
The phase diagram of the La-Co-Ni (La 32.2 wt%) ternary system at room temperature has been determined by X-ray powder method and metallographic examination.The isothermal section at room temperature was found to consist of four single-phase regions: α,β, LaCo13 and LaCo5xNi5-5x; five two-phase regions: α+β, α+LaCo13, β+LaCo13, β+LaCo5xNi5-5x and LaCo13+LaCo5xNi5-5x; two three-phase regions : α + β + LaCo13 and β+LaCo13+LaCo5xNi5-5x. No new phase has been observed in this range. X-ray analysis showed that the maximum solubility of La in β is about 9 wt%.
INTERGROWTH AND DISORDER STACKING IN THE CRYSTAL STRUCTURE OF ALKALINE-EARTH-CERIUM FLUOROCARBONATE MINERALS
1982, 31 (5): 680-684. doi: 10.7498/aps.31.680
The cerium fluorocarbonate minerals containing both calcium and barium have been studied by the lattice imaging technique. It has been found that the crystal structure of such minerals are formed by stacking at random along the direction c layers of various barium-Cerium as well as calcium-cerium fluorocarbonate minerals. The inter-growth of some calcium-cerium fluorocarbonate minerals with different composition has been observed in the range of several angstrons. A possible new polytype in Roentgenite has been proposed. The results show the advantage of the lattice imaging technique in direct observation of the crystal structure of such minerals.
1982, 31 (5): 685-689. doi: 10.7498/aps.31.685
The crystal of 15-crown-5 nitrate praseodymium with composition Pr(NO3)3C10H20O5 belongs to monoclinic system. The space group is C2h5-P21/α with lattice parameters α = 13.622?, b = 14.599?, c = 9.336?, β = 95°20′ and 4 molecules in the unit cell. The intensities of 2853 independent reflection were collected by the PW-1100 four-circle diffractometer. The structure was solved by heavy-atom method and refined to a final R = 0.080 by block diagonal least square method. The praseodymium coordination comprises the five crown oxygens (Pr-Ocrown= 2.545?) and two oxygens from each of the three bidentate nitrates (Pr-O(NO3-)= 2.685?). The coordination number is eleven.
1982, 31 (5): 690-692. doi: 10.7498/aps.31.690
This short note is a supplement of ref. , it also replies some points in the paper . We emphasize that in the kubo formula if we let v →∞ first and then △t→∞, the correct transport coefficient will be obtained. Expressing the transport coefficient according to the theory of approach to equilibrium can make the coefficient, which is indefinite in mechanical formalism, well definite. It is pointed out that to introduce the macroscopic current operator into the transport theory is unnecessary.
1982, 31 (5): 693-698. doi: 10.7498/aps.31.693
The coefficients of the series formula for the superconducting critical temperature have been determined by using the numerical solutions in which the value of λ is low. The new coefficients can be used not only in the case of small λ, but also in large λ cases.
1982, 31 (5): 699-703. doi: 10.7498/aps.31.699
Double tunnel junctions have been used to investigate the properties of superconducting Pb films under quasiparticle injection. At high injection level an inhomo-geneous gap state was observed.
The principle, possible applications and prospects of the scanning photoacoustie microscopy are described briefly. The microscopy system presented herewith attains a resolution of about 4,5 μm. Some images of such samples as the interdigital transducer of surface acoustic wave, integrated circuit and in particular the subsurface structure of the materials have been obtained by measuring the amplitude or the phase angle of the photoacoustie signal. These preliminary results show the potential applications of this device in solid state physics, material science and even medical science.