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Vol. 31, No. 7 (1982)

1982-04-05
CONTENT
CAUSES AND CONTROL METHODS OF MAGNETIC PARAMETER DRIFTS FOR MAGNETIC BUBBLE LPE GARNET FILMS
SUN SHEN-TAI, XU ZU-HENG, DAI JING-LAI, FEI BO-MEI
1982, 31 (7): 857-864. doi: 10.7498/aps.31.857
Abstract +
The causes and control methods of the magnetic parameter drifts for magnetic bubble LPB garnet films are investigated. It is considered that the main cause of the magnetic parameter drifts is the garnet heterogeneous nucleation and growth of the supersaturated melt. The phenomenon of melt compositional drift is explained in terms of the effective concentration of melt nutrient Reff = R4-Rn-Re, where R4 is the original concentration of the nutrient, Rn is the nutrient concentration consumed by the heterogeneous nucleation and growth, and Re is the nutrient concentration consumed by the LPE films. The eonsumption of melt nutrient concontration in LPE process is equal to Rn+Re, and the effect of Rn on the magnetic parameters of LPE garnet films is much greater than Re. In the reheating control process Rn= 0, and the melt is relatively stable. Stirring of substrates may accelerate the heterogeneous nucleation and growth of the melt.
THE MAGNETO-OPTIC KERR ROTATION OF INDIUM-SUBSTITUTED SINGLE CRYSTAL BCVIG
ZHANG PENG-XIANG, LIU YU-LONG, WANG HUAN-YUAN, PANG YU-ZHANG
1982, 31 (7): 865-870. doi: 10.7498/aps.31.865
Abstract +
We have measured the saturated polar Kerr rotation of In-substituted single crystal BCVIG, {Bi3-2xCa2x}[Fc2-yIny] (Fe(3x)Vx)O12, in the spectra range of 0.45-0.80 μm. A rotation peak near 0.47 μm was found. The room temperature dependence of the rotation peak value 2θK(0.47μm) on the composition was obtained by varying the substitution quantity of In3+ and Bi3+. It was found that the Kerr rotation change sign abruptly when varying the composition across the magnetization compensation point, however, the absolute value of the rotation does not reduce when the composition approaches that point, while the total magnetization 4πMs, does decrease, we also found that, with the In3+ content increasing, the Kerr rotation is "enhanced" at first, reaching a maximum at y~0.15, and then reduces. Using a model that the total Kerr rotation is the Bi3+ enhanced superposition of the sublattice Kerr rotation, we explained the "enhancement" of Kerr rotation by indium substitution. From fitting the experiment results, we deduced the ratio of the sublattice rotation coefficients (α4/α8) to be about 1.5, that is, the absolute contribution of every Fe3+ on tetrahedral site to the magneto-optic rotation is about 1.5 times as large as that on octahedral site. The results demonstrated that a good magneto-optic material can be synthesized in x3+ substitution. Considering its low and variable magnetization, high Curie temperature and rather large magneto-optic rotation, the In-BCVIG system, surely, is a promising cadidate in the variety of usage of the magneto-optic devices.
FORMATION OF THE INTERNAL STRESS FIELD AND DISTRIBUTION OF MAGNETIC ANISOTROPY IN THE AMORPHOUS ALLOY RIBBONS
LIN ZHAO-HUA, DAI DAO-SHENG
1982, 31 (7): 871-881. doi: 10.7498/aps.31.871
Abstract +
The solidification progresses of rapidly quenching from high-tempersture melts to form amorphous alloy ribbons were analysed. It was pointed out that different regions of the amorphous ribbon have different advancing ways of solidification in the process of solidifying, thus different local stress fields will exist in these regions. The internal stress fields and the stress-magnetic anisotropies in different regions of the amorphous ribbon were calculated theoretically. The calculated results and their inferences can interpret satisfactorily the observed structures of the magnetic domain in the amorphous ribbons and some phenomena in the experiments of the domain's observations.
DAMPING EFFECT ON THE NONLINEAR STABILIZATION OF STIMULATED BRILLOUIN SCATTERING PROCESS
HE XIAN-TU
1982, 31 (7): 882-894. doi: 10.7498/aps.31.882
Abstract +
In this paper, we investigated the stabilization of stimulated Brillouin scattering due to the non-linearity. We are mainly interested in the Landau damping effect on non-linear stabilization, we thus solved the time, space and time-space equations and obtained the approximate analytical expressions for the field energy densities, field amplitude, saturation time and space size etc. as functions of various physical parameters.
A SIMULATION EXPERIMENT OF PHASE ADJUSTMENT FOR A PHASE-ADJUSTED FOCUSING LASER ACCELERATOR
DONG BI-ZHEN, ZHEN SHI-HAI, YANG GUO-ZHEN
1982, 31 (7): 895-903. doi: 10.7498/aps.31.895
Abstract +
In this work, a simulation experimental scheme of phase adjustments for a phase-adjusted focusing laser accelerator is discussed, and a method of specific design for the phase plate is given. We have produced the phase plate, and carried out the experiment of phase adjustment. The experimental results are consistent with the theoretical design.
THE ZERO-FIELD SPLITTING AND g-FACTORS OF d2 IONS IN A TRIGONALLY DISTORTED CUBIC CRYSTAL FIELD
MA DONG-PING, XU YI-SUN, HU ZHI-XIONG
1982, 31 (7): 904-914. doi: 10.7498/aps.31.904
Abstract +
By using the irreducible tensor operator method, two corollaries are derived from generalized Wigner-Eckart theorem and the results associated with the corollaries are obtained. For the d2 ions in a trigonally distorted cubic crystal field, we have considered both the interactions of all possible Vc and (Vt+Hs) and taken into account the coval-ent bonding and dynamical Jahn-Teller effects with reduction factors. The groundstate wave functions are obtained through successive perturbations. Then the formulas of g∥, g⊥ and D are derived.In application to vanadium corundum, results in agreement with the experiments are obtained by overall fitting of the theoretical values to the observed values of D, g∥, g⊥ and absorption spectrum.Finally, we discuss the problems involved in our model, methods, results and importance of consideration of all interactions.
MOLECULAR THEORY OF LIQUID CRYSTALS
SHU CHANG-QING, LIN LEI
1982, 31 (7): 915-921. doi: 10.7498/aps.31.915
Abstract +
Starting from a modified Kobayashi-McMillan hamiltonian, (1) phase diagrams of liquid crystals of long molecules are calculated in the mean field approximation; (2) orientation correlation functions are calculated; (3) magnetic birefringence experimental results (of Muta et al.) on homologous series are analysed and explained qualitatively for the first time; (4) apparent exponent △ is calculated and △ = 1.40 is obtained; (5) a new explanation of the even-odd effect of liquid crystals differing from that of Marcelja is proposed. The even-odd effect of supercooling temperature T* is calculated for the first time.
CALCULATION OF RANGE STATISTIC PARAMETERS FOR IONS IMPLANTED IN GaAs
CHENG ZHAO-NIAN, ZHU WEN-YU, WANG WEI-YUAN
1982, 31 (7): 922-931. doi: 10.7498/aps.31.922
Abstract +
Based on successive correction method, we have solved LSS equation numerically and calculated the range statistic parameters Rp,△Rp and R⊥ for ions implanted in GaAs. We propose simple formulas for initial values in calculating Rp,△Rp and R⊥; by using these formulas, the zero-energy divergence can be avoided and sufficient accuracy achieved. The expressions for β-integration are given to save computation time. Our numerical method and computer program can also be used to other ion-target systems.
THE SUPERCURRENT OSCILLATIONS WITHIN ONE FLUX QUANTUM PERIOD φ0 FOR WEAK LINKS (Ⅱ)——THE SUPERCONDUCTING RING CONTAINING A WEAK LINK
ZHANG YU-HENG, CHENG GENG-HUA
1982, 31 (7): 932-938. doi: 10.7498/aps.31.932
Abstract +
It is pointed out that if a superconducting ring containing a weak link is placed in a cavity, which is in resonant with the current flowing in the ring, i.e., when the frequency of the Josephson current or one of its n-th harmonies is equal to the cavity frequency, and if the cavity has sufficiently high Q-value, then the feedback of the stationary electric-magnetic wave will act on the ring itself and produce a small sinusoidal oscillation superposing on the primary sawtooth wave oscillating current. The period of the small oscillation will be φ0/n and its amplitude that of the sawtooth wave multiplied by 1/nπ.
BRIEF REPORT
THE THERMODYNAMIC PROPERTIES OF TWO-DIMENSIONAL SYSTEM
DU YI-JING, CHEN LI-RONG, YAN ZU-TONG
1982, 31 (7): 939-944. doi: 10.7498/aps.31.939
Abstract +
H. Kawamura studied the solid-fluid phase transition of a two-dimensional hard disk system by using the Collins' model, but the 4 co-ordination was neglected. In this paper, we have taken into account the 4 co-ordination and the attractive interaction. The thermodynamic functions of the two-dimensional system are calculated. The dependence of the transition point on the percentage of 4 co-ordination is studied. The equation of state and specific heat are discussed.
PRECISE MEASUREMENT OF THE POSITRON ANNIHILATION RADIATION IN ALUMINUM
WANG YUN-YU, ZHANG TIAN-BAO, TANG XIAO-WEI
1982, 31 (7): 945-947. doi: 10.7498/aps.31.945
Abstract +
The radiation of positron annihilation in two aluminum samples from different origins was measured with the Ge(Li) detector. Using the 482 keV γ peak of 181Hf as reference, the relative positions of the annihilation peak centers were repetitively determined, the precision of the determination reached ± 6 eV. The results show that the rest mass of electron in these two different aluminum samples is consistent on 10 eV level.
CRYSTAL STRUCTURE OF THE LOW TEMPERATURE FORM OF BARIUM BARATE Ba3(B3O6)2
LU SHAO-FANG, HE MEI-YUN, HUANG JIN-LING
1982, 31 (7): 948-955. doi: 10.7498/aps.31.948
Abstract +
In this paper, we report the crystal structure of the low temperature form of barium borate-a new type of SHG material. Ba3(B3O6)2 crystal belongs to trigonal system with space group C34-R3. There are 6 formula units in one hexagonal cell. The unit cell dimensions referring to hexagonal axes are a = b = 12.532?, c = 12.717?. Diffraction data were collected on Philips PW-1100 four-circle diffractometer. The number of independent reflections amounts to 693. The structure was determined by conventional three-dimensional Patterson and Fourier syntheses and refined by "block diagonal" matrix least-squres procedures to R = 0.046. This structure can be considered as a layer step type of lattice built up by Ba2+ and (B3O6)3- rings atterna-tively. The anion (B3O6)3- group is nearly planar with its plane perpendicular to the threefold axis which passes through the center of the ring. Each barium atom has seven oxygen neighbors. In comparison with the high temperature form of barium borate, it is shown that the acentric symmetry of the barium cations in this structure changes the electron density distribution of the inorganic conjugated boron-oxygen rings, thereby making principal contributions to the SHG effect.
RESEARCH ON DIBENZO-18-CROWN-6 AND YTTRIUM ISOTHIOCYANATE COMPLEX (Ⅱ) ——DETERMINATION OF THE CRYSTAL STRUCTURE
YAO XING-KAN, YAN SI-PIN, WANG GEN-LIN, XU ZHANG-BAO, GU YUAN-XIN, ZHENG QI-TAI, SHEN FU-LIN
1982, 31 (7): 956-962. doi: 10.7498/aps.31.956
Abstract +
Dibenzo-18-Crown-6 Yttrium Isothiocyanate crystal is the complex of Crown and Yttrium Isothiocyanate. The molecular formula is C23H24O6N3S3Y. The crystal belongs to the orthogonal system, with space group D2h-Pmcn. The cell dimensions are a= 19.885(9)?, b = 17.283(8)?, c = 7.942(3)?. Pour molecules are contained in a cell (z = 4). The nine-coordination polyhedron around the Y(111) ion was formed by six oxygen atoms and three nitrogen atoms of three NCS- acid radicals in the molecule. The space group of the molecule is Cs. The intensity data were collected on a PW-1100 four circle diffractometer. The total number of independent diffractions amounts to 2859. The crystal structure has been determined by Patterson method and the refinement of the structure parameters was achieved by block-matrix least-square method, R=0.073. All the positions of hydrogen were located by the difference syntheses.
DETERMINATION OF CRYSTAL STRUCTURE OF NORSESQUILERPENOID LACTONE
GU YUAN-XIN
1982, 31 (7): 963-968. doi: 10.7498/aps.31.963
Abstract +
The molecular formula of Norsesquilerpenoid Lactone is C14H20O3. The crystal belongs to the orthogonal system, with space group D24-P21 21 21. The cell dimensions are α=7.526(3)?, b=24.642(10)?, c=6.887(2)?. Four molecules are contained in a cell (z = 4). Intensity data were collected on a RASA-IIS four circle diffractometer.The original MULTAN-80 was proved to be not successful in solving the structure. The correct structure solution was obtained by improving distribution of reflexion indexes.Finally, we analyse the cause of failure that original start set created and give reason for selecting new one.
ARTIFICIAL PHASE DEGENERATION IN THE DETERMINATION OF NON-CENTROSYMMETRIC STRUCTURES (Ⅱ) ——AN EXAMPLE OF SOLVING A COMPLEX HEAVY ATOM CONTAINING CRYSTAL OF SPACE GROUP P21
PAN HAI-FU, GU YUAN-XIN
1982, 31 (7): 969-971. doi: 10.7498/aps.31.969
Abstract +
In this paper, the method of artificial phase degeneration has been examined with a complex heavy-atom-containing crystal structure. The result obtained is satisfactory.
AN ITERATIVE CORRECTION METHOD FOR INDEXING THE X-RAY POWDER DIFFRACTION PATTERNS
GUO CHANG-LIN, HUANG YUE-HONG
1982, 31 (7): 972-976. doi: 10.7498/aps.31.972
Abstract +
In this paper, we suggest an iterative correction method for indexing powder diffraction patterns when the rough unit-cell dimensions are known. When the error of the original rough unit cell dimensions is not very large (<1-3%) and the measurement data of diffraction line are precise (△2θ<0.04°), satisfactory results can be obtained.
AUTOMATIC INDEXING OF ELECTRON DIFFRACTION PATTERNS FROM TILTED CRYSTAL
YANG QI-BING, ZHANG XIU-MU, CHANG XIN
1982, 31 (7): 977-980. doi: 10.7498/aps.31.977
Abstract +
The formula of indexing electron diffraction patterns from tilted crystal is as follows, [hkl]=[xy0]Γ(θ)Γ(ω0-ω)Γ(θ0)P-1H, where θ,ω are rotating angles and θ0,ω0 primary ones. A program applicable to all the crystal Systems has been worked out. This method is simpler and faster than that of stereographic projection.
AN EFFECTIVE METHOD FOR INDEXING KIKUCHI LINES FROM UHVEM
YANG QI-BING
1982, 31 (7): 981-987. doi: 10.7498/aps.31.981
Abstract +
The difficulty of automatic indexing of Kikuchi lines by computer lies in exper-mental errors in the mesurements of Kikuchi line positions and the camera constant. These errors were minimized by adopting a least square method to fit Kikuchi lines and correcting camera constant automatically. In addition, the geometry of lattice planes was used to aid the indexing of Kikuchi lines. Consquently, the reliability of correct indexing has been greatly improved. This method is universally applicable, however, it is, in particular, suitable to the case of Kikuchi lines from UHVEM.
THE HEXAGONAL METASTABLE PHASE FORMED IN AN AMORPHOUS Ni-P ALLOY DURING CRYSTALLIZATION
GUO KE-XIN, LIANG JIN-ZHONG, WU YU-KUN, MENG XIAN-YING
1982, 31 (7): 988-993. doi: 10.7498/aps.31.988
Abstract +
By tilting the needle like crystals in a partially crystallized Ni P amorphous alloy in a transmission electron microscope, the lattice type of a metastable phase with approximate composition Ni2.2 P has been uniquely determined to be hexagonal, α = 6.73? and c = 9.42?. In the c direction, the layer stacking sequence is AA…. High resolution lattice image of the (001) planes as well as the diffraction streaks in c* direction both indicate the presence of one dimensional disorder in stacking of the hexagonal layers.
INFRARED ABSORPTION STUDIES ON NEUTRON IRRADIATED FZ-Si CONTAINING HYDROGEN
ZHANG ZHENG-NAN, XU ZHEN-JIA
1982, 31 (7): 994-1000. doi: 10.7498/aps.31.994
Abstract +
Hydrogen related defect states generated in n-FZ Si(H2) single crystal after neutron irradiation have been studied by IR absorption. We observed some new absorption peaks that have not yet been reported. These peaks appear at 1992cm-1 and 1857 cm-1 in non-irradiated and irradiated specimens respectively. All absorption peaks arising from hydrogen and hydrogen related defects of n-FZ Si(H2) before and after neutron irradiation have been both discussed and assigned. And the 2150cm-1 absorption peak is attributed to the hydrogen donor.