Vol. 37, No. 1 (1988)
1988-01-05
CONTENT
1988, 37 (1): 1-10.
doi: 10.7498/aps.37.1
Abstract +
On the assumption of stationary states, the effective mass theory is extended to the of superlattices in electric field. When the tunnel penetration factors are small, the calculation results are in agreement with those of tunnel resonance method. Subbands, wavefunc-tions and optical matrix elements are calculated. It is found that the shifts of particle densities and energies of the second excited states are opposite to that of ground states. In the electric field the overall shape of subbands is close to that without electric field but the double degeneracy is removed. With the increase of electric field, the selection rule △n=0 goes over to △n =±1 gradually, this change-over occurs at moderate electric field.
1988, 37 (1): 11-19.
doi: 10.7498/aps.37.11
Abstract +
The theory proposed by P. Vogl ct al. is extended to the 3d-transition metal impurities doped GaAs1-xPx alloy system. For different compositions, i.e. different x, the acceptor levels, donor levels, local charges and spin-densities of different 3d impurities are predicted. The theory agrees well with the relevant experimental data and reveals their major chemical trends. The physical mechanisms which are responsible for the variation trends of theoretical and experimental results are also discussed.
1988, 37 (1): 20-28.
doi: 10.7498/aps.37.20
Abstract +
We present here studies of laser imploded glass microballoons by the newly developed time-resolved four-frame X-ray shadowgraphy. The simulation results of our one-dimensional Lagrangian hydrodynamical computation code (WL code) are in good agreement with the diagnostic experiments. The joint effort of the diagnostic experiments and theoretical simulations is crucial to understand laser implosion dynamics.
1988, 37 (1): 29-35.
doi: 10.7498/aps.37.29
Abstract +
The electron structures of amorphous Nb100-xNix (x= 65, 59.8, 56.4) alloys are studied by means of UV-Photoelectron spectroscopy (UPS). It is found that the position of the Fermi level is located near the minimum of the density of states, which explains the double Curie-point phenomena in Nb-Ni alloys. Analysing the electron structure of Nb-Ni alloys, it is pointed out that the hybridization of two d-bands with energies close to each other may form a new hybridizated band near EF and the hybridization is related to the valence difference. The charge transfer makes the peaks of bands shifting. The density of states of TE-TL. alloys at EF should include two parts of contributions, i.e., that from 3d electron stsates, which is of advantage to magnetism, and that from 4d electron states, being of advantage to superconductivity. Different ratio of these contributions at Er influences the magnetism and superconductivity of the alloys greatly. The coexistence of localized magnetic moments and superconductivity has also been discussed.
1988, 37 (1): 36-42.
doi: 10.7498/aps.37.36
Abstract +
A calculation of magnetic single-ion anisotropy in hematite (α-Fe2O3) has been made, based on point-charge model in crystalline field. The nearest-neighbor O2- ions and the nexi-nearest-neighbor Fe3+ ions were chosen as ligands and the effect of electrostatic shield provided by the O2- ions was taken into account. Considering the sixth order perturbation, we ob-tained an equivalent single-ion anisotropy field Hsi=102.3×102 Oe. Making use of this results in conjunction with the computed equivalent dipolar anisotropy field by Artmen et al,. the Morin transition temperature in hematite TM=261 K was obtained, which is in good agreement with the experimental value. Based on the linear approximation principle, we got the TM-n relation for low n value in α-(Fe-1nAln)2O3. With this relation the dependence of the-Morin transition temperature, TM, on n in low n value range could be explained quite well.
1988, 37 (1): 43-48.
doi: 10.7498/aps.37.43
Abstract +
The coordination number Z of the atom W in scintillator ZnWO4 is analyzed based on the X-ray structural data and Raman scattering experiment results. Z is suggested to be 6 that might be more reasonable than 4. t turns out that the luminescence center in ZnWO4 locates at the configuration of the atomic group WO6, instead of WO4-2. We also present some new Raman lines expected bytheoretical analysis.
1988, 37 (1): 49-56.
doi: 10.7498/aps.37.49
Abstract +
A short range structure investigation of halide glasses (MnF2)x(BaCl2)100-x(x = 65, 60, 55) has been made using the extended X-ray absorption fine structure (EXAFS) and the wide angle X-ray scattering (WAXS) techniques. The local structure information around the Mn is derived from the study of the MnK absorption edge EXAFS and the X-ray scattering intensity of the materials, respectively. The results show that the F and Cl atoms in the first neighbour shell of the Mn atom construct a octahedra (MnCl2F4) with the bond-length rMn-Cl = 0.246 nm and rMn-F= 0.200 nm in the glass of x = 65, which share the atom F with the neighbouring one to form zigzag chains linked by Ba atoms distributed between them. With decreasing of the amount of MnF2 below x = 65, the bond-length rMn-Cl and the Debye-Waller factor σMn-Cl2 of Mn-Cl increase, and that of Mn-F is almost invariant. The disappearance of the Mn-Mn peak has been found from x = 60 to x = 55 with an abrupt increase in rMn-Cl and σMn-Cl2, which can be explained as the chains being broken to form the solitude octahc-dra (MnCl2F4).
1988, 37 (1): 57-63.
doi: 10.7498/aps.37.57
Abstract +
Amorphous superionic conductor (AgI)x(Ag4P2O7)1-x system has been obtained by means of the liquid nitrogen rapid quenching technique. The ultrasonic attenuation and velocity of longitudinal and transverse sound waves in the samples for Agl with mol concentration x = 0.50, 0.60, 0.67, 0.75, 0.80 were measured in the temperature range 77-300 K at the frequency of 2, 5, 10, 15 MHz. An anomalous strong ultrasonic absorption peak is observed at a temperature around 200-240 K with the rharacteristics of relaxation attenuation evidently. The attenuation peak was found to shifts to lower temperature and the peak attenuation value increases with increasing Agl content. In the experimental temperature region the internal friction QM-1 of longitudinal and transverse waves in the samples is almost equivalent. In the course of attenuation measurements the sound velocity, elastic moduli at room temperature and the dependence of sound velocity on Agl content were also measured. The experimental data fit satisfactorily the unified theory of low frequency fluctuation, dissipation and relaxation process (i.e. infrared divergence response theory, briefly called as IDR) proposed by Ngai. The apparent activation energy and infrared divergence exponent of the samples were presented.
1988, 37 (1): 64-70.
doi: 10.7498/aps.37.64
Abstract +
The concentrated suspension theory in granular media set up by the author is presented concisely in this paper. By comparing its numerical results with the relevant data published, a satisfactory consistency can be obtained. As far as the relationship of the attenuation coefficients in marine sediments to the frequency is concerned, there has been a controversy among some authors for a long time, i.e. it appears to be a linear dependence upon frequency in the high-frequency range (higher than several kilohertz) and to be some deviation from first power dependence in the low-frequency range (lower than 1 kilohertz). However, according to our theory, reasonable unity can be acheived for them. Through an investigation on the measurement of the granular media by means of the acoustic method, the author believe that besides the mean diameter, the second granular parameter (such as the sorting coefficient) is necessary for a full characterization of granular media.This theory may give a theoretical basis to design new equipment for measuring granular parameters.
1988, 37 (1): 71-76.
doi: 10.7498/aps.37.71
Abstract +
Depth profiling of hydrogen in solids has been performed by Elastic Recoil Detection (ERD) with multicharged F ions at a 1.7 MV Tandem accelerator. Both experimental and theoretical analysis show the depth resolution of about 200-300 ? in the near-surface regions of solids. The optimization of the experimental conditions such as scattering geometry and incident beam energy are discussed. The comparison of ERD with multicharged F ions and 1H(19F,αγ)16O resonance reaction at 6.4 MeV for the same samples demonstrated that hydrogen profiling by ERD with F ions is a fast and economic method with low radiation damage and perfect depth resolution.
1988, 37 (1): 77-86.
doi: 10.7498/aps.37.77
Abstract +
In this paper, the general structure of linear Jacobian matrices of even periodic orbits for reversible area preserving maps is obtained and two kinds of bifurcation behaviour of symmetric periodic orbits are discussed from the above structure. We present the conditions and the analytical criterions which can distinguish three types for equal periodic bifurcations of reversible area preserving maps. The applications of this analytical method are illustrated with several examples of De Vogelaere map.
1988, 37 (1): 87-94.
doi: 10.7498/aps.37.87
Abstract +
Based on the intraatomic electron correlation and the interatomic electron and spin correlation, the local approach has been used to the Hubbard model. The term〈OOH〉which was neglected in the general calculation is retained in our calculation. Camparing our results with those of the general calculation, we find that when U is large, the effects of the term〈OOH〉in the paramagnetic phase can not be heglected for calculating the correlation energy, the ground state energy, the local moments and the antiferromagnetic polarization around the local moments. To estimate more accurately the electron correlation effects, one has to calculate to higher orders and check he convergency of the series.
1988, 37 (1): 95-104.
doi: 10.7498/aps.37.95
Abstract +
The classification of the static magnetic domain wall structures of tube- and envelope-type is made in an unified way using the homotopy theory. The sets of topological classes for such two kinds of magnetic domain walls, GWn and GWn, are corresponding respectively one-by-one to the sets of homotopy classes relative to n + l base points for the S2→S2 and S3→S4 continuous maps. Either GW(n) ro GW(n), therefore, can be constructed into group isomorphic to Z, the additive group of integers. (Then we call them the tube-wall group and the envelope-wall group of type n, respectively). The ‘winding number' introduced by Slon-czewski et al. is considered anew. The sufficient and necessary conditions under which the ‘winding number' is allowed to be taken as the index of tube-wall class are obtained. Finally, the topological classification of the magnetization states with M tube-walls and N envelope-walls coexisting is discussed. It is shown that the set of the corresponding topological classes, GW(M,N), can be constructed into group isomorphic to ZM+N, the M + N dimensional lattice vector group. (It is then referred to as the mix-wall group of type [M, N] ).
1988, 37 (1): 105-110.
doi: 10.7498/aps.37.105
Abstract +
In this paper, we present the general spinor structure of 3-dimensional wave functions of mesons with natural JPC and the system of equations satisfied by 3-dimensional wave functions. They are classified into three classes in the choice of the Spinor structure of potentials which is phenomenologically reasonable, a kind of spinor structure of 3-dimensional wave functions is solved.
1988, 37 (1): 111-118.
doi: 10.7498/aps.37.111
Abstract +
The thermodynamic critical field of superconducting state, the jump of the specific heat at Tc and the behaviors of the specific heat below Tc have been calculated by using the modef and the gap equations given in Ref [1] . It is shown that the critical values of the thermodynamic quantities are qualitatively in agreement with the experimental results,and the behaviors of the specific heat are in accordance with those results of CeCu2Si2 and UBe13 at all temperatures.
1988, 37 (1): 119-127.
doi: 10.7498/aps.37.119
Abstract +
The behavior of periodic orbits of the standard mapping near their residues R =1 and R = 0 is studied. There is a sequence of period doubling bifurcations corresponding to the former, the bifurcation ratio δ and scaling factors α and βagree with those obtained from other two-dimensional area-preserving mappings. There are same period bifurcations corresponding to the latter, which is related to the antisymetric nature of the standard mapping. Moreover, by calculating Lyaponov exponents of chaotic orbits, we have found near the accumulation point k∞ of a sequence of period doubling bifurcations a scaling relation λ=λ∞+A(k-k∞)+B(k-k∞)τ with τ≈0.32, it agrees with the result τ=ln(2)/ln(δ)(δ=8.7210972…) conjectured theoretically.
BRIEF REPORT
1988, 37 (1): 128-131.
doi: 10.7498/aps.37.128
Abstract +
A theorem is established that if the topoiogical space V is simply connected, the set of homotopy classes for the Sn→V continuous maps with N(≥1) base points, πn (V; v1, v2,…, vN), can be constructed into group isomorphic to the homotopy group of order n with single base point, πn(V) (referred to as the homotopy group of order n with N base points). Here, the condition that V is simply connected could not in general be neglected. Some corollaries are given. The application of this theorem and its corollaries to the topoiogical classification of magnetization states in ferromagnet is briefly- described with a few examples.
1988, 37 (1): 132-135.
doi: 10.7498/aps.37.132
Abstract +
The equiscale transformation in the same universality class developed previously[a,5] is applied to the generalized mixed spin model, the curve of the crkical temperature is obtained for this model.
1988, 37 (1): 136-140.
doi: 10.7498/aps.37.136
Abstract +
The effect of electric field applied along [111] on EPR spectra of SrCl2:Co++ has been investigated. The result shows that electric field causes the crystal lattice to distort and deviate from its original cubic Oh symmetry to C3v symmetry. We have successfully explained the experimental rule that zero field splitting parameter D depends linearly upon electric field strength E and also predicted the coefficients of the change of the structure parameters a = - 8×10-5 a0 mm/kV (parallel to the electric field), β= 1.66×10-4 a0 mm/kV (perpendicular to the electric field).
1988, 37 (1): 141-146.
doi: 10.7498/aps.37.141
Abstract +
In this paper, we seport the coleulation of electronic states in ionic crystals in the fram-work of molecular cluster model. A convensinal CNDO/INDO program for the calculation of mole cular structure was revised to meet the requirments of calculation for electronic states of ionic crystals.The electronic states of crystals LiF, NaF, LiCl, NaCl were calculated. Width of valence band, band gap, effective ionic charge and the position of ground state louel of F-center in LiF were obtained. A comparison between our results and that proposed by other authors and experimental data has been made. Our results agree fairly good with experimental data.
1988, 37 (1): 147-151.
doi: 10.7498/aps.37.147
Abstract +
The electron paramagnetic resonance of Fe3+ ion in α-Al2O3 single crystal has been studies at room temperature in x-band. It is found that Fe3+ ions occupy actually four magnetically unequivalent sites. The Fe3+ ions in two kinds of sites between adjacent planes of oxygens have same Spin Hamiltonian Parameters (SHP), but have different SHP in the sites between next adjacent planes of oxygens. Two groups of SHP are: (1) g‖=2.001, g⊥= 2.003, D= 1679×10-4 cm-1, |a| =237×l0-4cm-1, a-F = 317×10-4cm-1. (2) g‖ = 2.001, g⊥= 2.006, D=l660×10-4cm-1, |a| = 243×10-4cm-1, a-F=338×10-4cm-1.
1988, 37 (1): 152-156.
doi: 10.7498/aps.37.152
Abstract +
The B-doped (100) CZ-Si single crystal films were implanted with 50 and 100 keV hydrogen ions in the concentration range of 1015-1017H+/cm2. The implanted specimens were electron irradiated at l000keV in HU-1300 HVEM. It was found that the electron irradiated defect density was higher ia Si with no hydrogen than in hydrogen implanted Si at the same irradiation condition within the temperature range 298-573 K. When hydrogen implanted Si films were heated insitu in HVEM from room temperature to 823 K, The hydrogen blisters were formed in k at about 473 K. The critical hydrogen concentration in Si for the formation of blister was 9×1016 H+/cm2. Hydrogen blisters had the form of convex lens with diameter 1000-5000 nm. The blister number density was about 1017/m2 in the 1017H+/cm2 implanted Si The formation of blister is related with the dissosiation of silicon-hydrogen bond in Si.
1988, 37 (1): 157-161.
doi: 10.7498/aps.37.157
Abstract +
Room temperature photoreflectances of a MBE GaAs doping superlattice were measured under different pump beam intensities. A series of fine structures corresponding to forbidden transitions (△n≠0) were observed af lower pump beam intensities. This means it is net a third derivative spectrum. A first derivative lineshape of photoreflectance for doping super-lattices was suggested, and the modulation mechnism was discussed. Theorefical calculations give a good explanation to the experiments.
1988, 37 (1): 162-166.
doi: 10.7498/aps.37.162
Abstract +
With the model of five-atom clusters in virtual crystal background and the recursion method, we calculated the phonon spectra of Ge1-xSix mixed crystal. The developement processes of vibrational modes were analysed in detail.
1988, 37 (1): 167-171.
doi: 10.7498/aps.37.167
Abstract +
The thermal properties for PTS are studied by photoacoustic effect in temperature range 175-225 K. It is found that there is a peak of C3K at 200 K (here C3 and K are the specific heat and thermal conductivity of PTS, respectively), which shows crearly the existence of a second order phase transition in view of thermal propertis for the first lime. An anomalous thermal conductivity in the above temperature range is deduced from experiment results.
1988, 37 (1): 172-176.
doi: 10.7498/aps.37.172
Abstract +
The electronic structures, the positron behavior and the positron annihilation lifetimes for void-H, void-He, void-Kr complex in the transitiou metals Ni, Fe, Cr and the noble metal Cu have been calculated, by means of the density functional formalism, the local density approximation based on the jellium model. It is shown that: as the size of the complex increases, the energy levels of bound state of impurity become shallower; and consequently the mean density of scattering state electron inside the complex decreases; and the probability of positron inside the complex and the positron annihilation lifetime inceases.
