Vol. 36, No. 8 (1987)
1987-04-20
1987, 36 (8): 965-973.
doi: 10.7498/aps.36.965
Abstract +
The far infrared reflection spectra of n GaAs_(1-x)_P_x_ with x=0.328 and x=0.40 are investigated in the frequency range of 40-700 1/cm and the temperature range of 4.2-300K. The important physical parameters describing the optical phonons, Plasmon and LO phononplasmon coupling mode of the material and infrared optical constants are obtained by the multioscillator fitting and K-K relation calculation. A model of two conduction band valley with a donor level below and associated with X minimum is present to explain the behavior of the dependence of plasmon frequency temperature on temperature and the variation of the three coupling modes with temperature.
1987, 36 (8): 974-980.
doi: 10.7498/aps.36.974
Abstract +
For poly-crystalline semiconduetor film deposited on an insulator and then recrystallized by a laser beam, the influence of the substrate upon recrystallization of the film was analyzed theoretically. We found the critical laser power necessary for solid-liquid phase transition to take place, will change to a lower value as the poor thermal conduction of insulating substrate being reasonably considered. It is well known that the existence of stress in recrystallized films may be taken as a criterion for melting process that undergoes during laser lrradiation. A large number of SOI samples prepared by LPCVD technology were studied after its laser recrystallization, to obtain the critical transition conditions through strass determination by use of Raman peak shifts. A comparison of the calculations based on the model taking low thermal conductance of the substrate into account with the experimental results showed its fitting is better than that with the influence of substrate being neglected.
1987, 36 (8): 981-985.
doi: 10.7498/aps.36.981
Abstract +
The electronic energy band structures of CeSn_3 and CeIn_3 are studied with LMTO-ASA method. The behavior of the f-electrons of Ce and the hybridization between f-orbitals and the s, p, d orbitals of non-f-atoms are discussed. The density of states and energy bands are investigated, especially in the vicinity of Ef,
1987, 36 (8): 986-991.
doi: 10.7498/aps.36.986
Abstract +
The oxide precipitates (1000-6000A) were separated from as-grown CZ silicon crystal containing the swirl defects by means of chemical etching method. The selected-area electron diffraction analysis of the precipitates, which had been prepareted into the extraction replica specimens, was carried out in TEM. Simultaneously, the morphology of the swirl defects in silicon thin foil specimens was observed with TEM. Thereby, the corresponding relation between the particles in the extracrion replicas and the swirl defects in the silicon thin foils was established. It was concluded that a great number of the swirl defects are keatite (silica k) in the form of square-shaped platelets with {100} habit planes and sides in parallel with direction, and a small part of the swirl defects are a-cristobalite in the form of hexagon-shaped platelets with {111) habit planes and sides in parallel with . IR absorption spectra of as-grown CZ silicon samples showed that the square plate-shaped keatite were probably associated with the absorptior band at 1224 1/cm.
1987, 36 (8): 998-1003.
doi: 10.7498/aps.36.998
Abstract +
The phenomenological atomic potential model with analytical solutions is employed to obtain the wave functions of the Rydberg states (10≤n≤40) and the oscillator strengths of the ns--n'p ,np--n'd, and nd--n'f transitions between them. The results are very close to those obtained by the CA method. These results show that there exists a kind of sealing law for the above oscillator strengths.
1987, 36 (8): 1004-1009.
doi: 10.7498/aps.36.1004
Abstract +
Montmorillonite samples treated at different temperatures had been studied by XRD. The (00l) reflections of some samples disappeared, and reappeared under some conditions. The crystallographic significance and the possible phase transformation had been discussed.
1987, 36 (8): 1010-1018.
doi: 10.7498/aps.36.1010
Abstract +
Taking account of two-and three-body interaction of the nearestneighbours, the acoustic modes of NXN square lattice is solved in harmonic approximation. The boundary coupling effect leads to physical pictures of phonons different from those in infinite lattice. The standing wave phonons can only be classified according to space species, and the wave vector losses it’s sense. Numerical computation shows that the strengthening of the covalent property leads to appearance of a boundary coupling soft mode. The modes related to rotation, inner-rotation, C/I structure, and surface wave phonon are also given. The phonon spectrum of finite lattice extends to the lower and higher end. The effects in three dimensions are also considered.
1987, 36 (8): 1019-1026.
doi: 10.7498/aps.36.1019
Abstract +
In this paper, the critical exponents of the Potts model are calculated by using the exact decimation with mean-field approximation method. The results obtained are in good agreement with that of the exact calculation. The accurary of this method is better than other renormalization group methods.
1987, 36 (8): 1028-1032.
doi: 10.7498/aps.36.1028
Abstract +
The effects of cold plasma and conducting end plates on interchange instability of finite-length hot electron plasma are studied. A dispersion relation including line-tying is deriver, and new stability criteria are found. Strong line-tying effect can greatly reduce the threshold of density ratio needed for stabilizing interchange mode of hot electrons. The modes with low in and long wavelength may be stabilized more easiiy.
1987, 36 (8): 1033-1040.
doi: 10.7498/aps.36.1033
Abstract +
The X-ray K absorption spectra of iron in metglas Fe_80_B_20_ and Fe_80_Si_6_B_14_ are measured, using the rotating anode X-ray generator and the EXAFS spectrometer with bend crystal. The structural parameters of near neighbor of these metglases are determined by EXAFS. Besides, their XANES are also measured. While comparing the XANES of iron inmetglases with that in a-Fe, FeB andFe_2_B, we discovered some changes on the energies of their absorption edge and the characters of “white line” These show that there is stronger interaction between near neighboring atoms Fe-B, Fe-Si and Fe-Fe in metglases than that in the stable compounds of iron and boron. And this has an important effect on the shortrange order structure of these metglases.
1987, 36 (8): 1041-1047.
doi: 10.7498/aps.36.1041
Abstract +
Hall effects of amorphous InSb and its metastable intermediate phases which appear in the process of thee crystallization phase transition have been studied. Experimental results show that the conduction of the electron is dominative in the metal-type amorphous InSb and the conduction of the hole is dominative in the semiconductor-type amorphous InSb. The first jump of the conductance is a process of the structure relaxation from the liquid-like amorphous state to the lattice-like one; the third jump of the conductance was caused by In-Sb solid solution with the rich In or rich Sb which was separated out and segregated on the grain boundaries. The three types of the crystallization phase transition of the metal-type amorphous InSb present obviously different transportion hehaviours. The rise of superconducting Tc of the metastable crystalline metallic phase which corresponds to the peak of the second jump of the conductance originates possibly from the increase of the electron concentration.
1987, 36 (8): 1048-1055.
doi: 10.7498/aps.36.1048
Abstract +
By use of the spinor-spinor Bethe-Salpeter equation of field theory, we assumed a phenomenolgical “flatl bottom” hadronic potential which is relativistically covariant. And the meson wave function was obtained in the momentum space.
1987, 36 (8): 1056-1059.
doi: 10.7498/aps.36.1056
Abstract +
It is shown that for general compact simple Lie groups and arbitrary value of coupling constant __ _, the equal time current algebra of the two dimensional non-linear __ model with Wess-Zumiuo term is a Kac-Moody algebra with center charge.
1987, 36 (8): 1060-1063.
doi: 10.7498/aps.36.1060
Abstract +
In the amorphous alloys Nb_(1-x)Ni_x_(x= 0 .564 , 0 .595 , 0.65 ), we observed the double Curie temperature phenomenon of itinerant electron magnetism and also the typical susceptibility cusp for spin glass freezing. In this alloy system, both itinerant electron magnetism and localized magnetic appear very clearly.
1987, 36 (8): 1070-1074.
doi: 10.7498/aps.36.1070
Abstract +
The hydrogen adsorption on GaAs and InP surfaces was studied by high resolution electron energy loss spectroscopy (HREELS). The stretching vibration modes of Ga-H,As-H, In- H and P-H bonds corresponding to different energy loss peaks in the spectra were all observed. However, the As-H vibration mode was usually confused with Ga-H“Phonon echo”peak which is the Ga-H vibration mode plus an optical surface phonon loss. The identifying of As-H from the“Phonon echo”peak could be done only by comparing the relative intensities of the loss peaks. The experimental HREELS show that the bonding between the adsorbed hydrogen and the surface atoms was determined largely by the surface atomic structure and electron distribution. For the GaAs(111) surface, only surface Ga atoms form bonds with the hydrogen under low exposure, while at high exposure both As-H and Ga-H bonds could be formed. On InP(111) surface which was treated by annealing under phosphorus pressure, in addition to the In-H bond the P-H bond was formed even at low exposure. Only P-H loss peak could be seen on InP(111), which suggested that such surface was fully terminated with P atoms. In the case of forming facets on (111) surface, both surface group 111 and group V atoms could from bonds with hydrogen.
1987, 36 (8): 1075-1080.
doi: 10.7498/aps.36.1075
Abstract +
The presence of surface state originated from T-3+ ion on reductive SrTio3 been observed. The action of Ti-3+ on photodecomposition of water and the action of light irradiation on regeneration of activity are analysed.
1987, 36 (8): 1081-1086.
doi: 10.7498/aps.36.1081
Abstract +
The expression for intensity distribution and computer simulated images of screw dislocations with Burgers vector l/2 (111) viewed end-on in gernet crystals subjected to a long-range strain have been obtained by considering only the anisotropy of the photo-elastic property of the material. The computer-simulated images of end-on screw dislocations show two fold symmetry with a pair of dark and bright petals which result from the effect of a longe-range plane strain field superimposed on screw dislocation. The computer-simulated images are in good agreement with the experimental images in GGG crystals.
1987, 36 (8): 1087-1092.
doi: 10.7498/aps.36.1087
Abstract +
Based on the characteristics of superionic glasses and a physical picture of unified theory of the low-frequency fluctuation, dissipation and relaxation phenomenon, the transport features of a non-Markovian process of conduct ions are explored. The theory predict that the frequency independent conductance follows a simple Arrhenius type dependence on temperature at high temperatures, The theory can also explain the frequency dispersion of the conductance at low temperatures, and the degree of the frequency dispersion depends on the infrared divergence exponent n.
1987, 36 (8): 1093-1098.
doi: 10.7498/aps.36.1093
Abstract +
In this paper, the influence of crystal field on the shift of center of gravity of rare earth ion are discussed theoretically. The shifts of the center of gravity of‘I , state due to the J-mixing effect occur in 15 crystals doped Nd3+ are calculated. The results show that the splitting width of spectral term,
1987, 36 (8): 1099-1104.
doi: 10.7498/aps.36.1099
Abstract +
The volume compression of a-LiIO_3_ has been studied by X-ray diffraction in a diamond anvil cell up to 23.0GPa at room temperature. The anisotropic compression of lattice was observed. The ratio of c/a of parameters decreased with a rate of -6.187x 10**(-3)/GPa with pressure. The bulk modulus of normal pressure and its first pressure deviative have been determined to be equal to 39.2 and 3.787GPa respectively. At high pressure and high temperature, hexagonal a-LiIO_3_ transformed to a tetragonal phase. The structure was the same as quenching-releasing pressure phase, i.e., the E phase.
