高压物理学报

Electron Transport in the Systems La2CuO4+ and La2-xSrxCuO4

ZHOU Jian-Shi, Chan J, Goodenough J B

1993, 7(2): 81-91 . doi: 10.11858/gywlxb.1993.02.001

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Abstract:
The temperature dependence of the resistivity and Seebeck coefficient for the two p-type systems La2CuO4+ (00.09) and La2-xSrxCuO4 (0x0.3) are interpreted.

Influence of Cr-Content on both Resistivity and Its Pressure Effect in Amorphous Fe-Zr Base Alloys

SU Fang, SU Jun, XU Wei

1993, 7(2): 92-99 . doi: 10.11858/gywlxb.1993.02.002

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Abstract:
The resistivity of amorphous Fe90-xCrxZr10 (x=2, 4, 7, 10, 13, 16, 20) alloys was measured in detail by a 4-probe dc technique under different hydrostatic pressure from 0.000 1 GPa to 2.5 GPa. It is observed that: (1) The resistivity 0 at room temperature and atmosphere pressure varies in a manner similar to the alphabet N as the content of Cr in amorphous Fe-Zr base alloys increases; (2) Relative resistivity /0 of amorphous Fe90-xCrxZr10 alloy drops monotonously when the hydrostatic pressure increases, the more the content of Cr, the smaller the decrease of resistivity; (3) Pressure coefficient of amorphous Fe90-xCrxZr10 alloys is quite sensitive to the variation in x; (4) Relation between /0 and x under 6 typical pressure was given. Finally we discussed the seletion of four physical models and the behavior of coherent exchange scattering under high hydrostatic pressure.

Effects of Pressure on the Crystallization Temperature and Activation Energy of Metallic Glass Zr70Cu30

SHEN De-Jiu, SHEN Zhong-Yi, WU Hao-Quan, YIN Xiu-Jun

1993, 7(2): 100-104 . doi: 10.11858/gywlxb.1993.02.003

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Abstract:
The crystallization temperature and activation energy of metallic glass Zr70Cu30 were studied in the pressure range up to 2 GPa by resistance measurement. In addition, the relation between the crystallization temperature and activation energy was discussed.

Formation of the Spherical-Like Recrystallized Graphite

HAO Zho-Yin, HE Yi-Xing, CHEN Yu-Fei, WANG De-Rong

1993, 7(2): 105-109 . doi: 10.11858/gywlxb.1993.02.004

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Abstract:
We have observed the change of recrystallized graphite morphology using a high-resolution electron microscope, and have found evidence of the diamond crystal-formation.

Pressure and Temperature-Induced Soft Mode Phase Transition in Bi1.8Nd0.2Ti4O11

CUI Qi-Liang, MENG Jin-Fang, ZOU Guang-Tian, ZHAO Yong-Nian, LI Dong-Mei

1993, 7(2): 110-114 . doi: 10.11858/gywlxb.1993.02.005

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Abstract:
The Raman spectra of Bi1.8Nd0.2Ti4O11 have been measured by backward scattering. Experimental results show that the phase transition pressure and temperature are 3.35 GPa and 200 ℃, respectively. The cause of the shift in the phase transition point and the variation of the high frequency phonon mode with temperature or pressure, were discussed in this paper.

The Critical Properties of Liquid-Gas for 2024Al

ZHANG Chun-Bin, GUO Quan-Lin, LI Mao-Sheng

1993, 7(2): 115-122 . doi: 10.11858/gywlxb.1993.02.006

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Abstract:
The critical properties of EOS with cold pressure in the form A(B-2) for 2024Al were studied here. Two modified forms of cold pressure of Morse potentials are presented and the critical parameters are calculated. We believe that the modified cold pressure forms are more reasonable than the early forms. The liquid-gas phase transition isotherm plateaus also calculated for 0K=0 and 0K0, respectively.

The Structure Phase Transition of Iodine at High Pressure

CEHN Liang-Chen, ZHANG Zhi-Ting, CHE Rong-Zheng, YU Ting-Nan, LI Feng-Ying, GU Hui-Cheng, XU Li-Wen, WANG Ji-Fang

1993, 7(2): 123-126 . doi: 10.11858/gywlxb.1993.02.007

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Abstract:
The structure phase transitions of iodine have been studied by using X-ray diffraction with a diamond anvil cell at high pressure up to 32 GPa. As iodine is reactive with iron in air, a corrosion-resisting and high-strength gasket was put between the diamonds, thus the sample can be mounted at atmospheric pressure and room temperature. Pressure was measured in terms of the ruby fluorescence and the molybdenum diffraction as an internal pressure standard. According to the X-ray diffraction results, iodine undergoes a structural phase transition at 21 GPa from face centre orthorhombic phase to body centre orthorhombic phase. A change of volume is 2%. At 21~25 GPa, the coexistence of two phases has been observed. Above 25 GPa, the single new phase of the high pressure structure appeared. When pressure goes inversely, this transition was found to be reversible.

The Relation between Fractal Dimensionality and Entropy

QU Shi-Xian, DONG Lian-Ke

1993, 7(2): 127-131 . doi: 10.11858/gywlxb.1993.02.008

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Abstract:
The relation between fractal dimensionality and entropy was demonstrated theoretically in the paper, in which the fractal dimensionality is a measure of the entropy and a state function. This is the physical meaning of fractal dimensionality. The relation between the configuration (information) entropy and the information dimensionality in amorphous structure could be used to prove our present conclusion. This result is of significance in the uniting of evolution dynamics and thermodynamics.

The Structure and Formation of Al0.77Mn0.19Yb0.04 Quasi-crystal by Quenching Technique under Static High Pressure

XU Da-Peng, SU Xin-Tang, YU Ri-Cheng, SU Wen-Hui, XING Zhi-Ming

1993, 7(2): 132-137 . doi: 10.11858/gywlxb.1993.02.009

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Abstract:
The T-phase quasi-crystal containing rare earth element of Al0.77Mn0.19Yb0.04 alloy has been obtained by the quenching (100 ℃/s) technique at fusion state (1 300 ℃) under static high pressure (4.2 GPa). The symmetry pattern of the quasi-crystal structure was observed and analyzed by selected area transmission electron diffraction technique; indices of the diffraction peak were obtained via XRD and electron diffraction method; the content each component was obtained from SEM and energy spectrum technique.

The Sound Velocity and the Attenuation of YIG and YAG Crystal under Pressure with and without an External Magnetic Field

GU Hui-Cheng, LI Feng-Ying

1993, 7(2): 138-142 . doi: 10.11858/gywlxb.1993.02.010

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Abstract:
YAG is a nonmagnetic garnet crystal and YIG is a ferromagnetic garnet crystal. The sound velocity and the attenuation of the ferromagnetic garnet and nonmagnetic garnet were studied at high pressures with or without an external magnetic field. The sound velocity was measured by Pulse echo overlap technique with Matec system model 6600. The attenuation was measured by comparison of the amplitudes of echoes. We found that both nonmagnetic garnet and ferromagnetic garnet have some similar ultrasonic behavior under pressures without magnetic field. We attribute it to their same garnet crystal structure. We also found that there exists magnonspin-phonon interaction in YIG but magnonspin-phonon interaction in YAG, even at high pressures.

The Technology for the Separation of Projectile from Its Seat in Hypervelocity Impact Study

WANG Jin-Gui

1993, 7(2): 143-147 . doi: 10.11858/gywlxb.1993.02.011

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Abstract:
This paper describes in detail the technology used in the separation of projectile from its seat in the hypervelocity impact study on the two-stage light gas gun. The results show that this technology which uses an interceptor to separate the seat from the projectile won't cause the loss of the projectile velocity and will also keep the coaxality of the original system. It is very effective for the separation (100%), though its structure is quite simple.

A New Concept on the Structure of the Catalyst in Diamond Synthesis

SUN Jiang, LI Ji-Fa, FENG Qing-Tian

1993, 7(2): 148-151 . doi: 10.11858/gywlxb.1993.02.012

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Abstract:
The circular sheet catalyst has been found useful for both six anvil and two anvil high pressure devices. But the single-output of the latter is about 50% higher than the former for the same chamber dimentions. In this paper, we analyzed the catalyst's surface characteristic and the relationship between the applied load and the strain of the catalyst assembly evaluated the function in the variation of the specific surface area as well as the shape of the catalyst. We conclude that the increase in contact area, or reaction area, between the catalyst and graphite is important for the enhancement of convention ratio of single-crystal fine diamond. To this end, the new concept of foam catalyst has been presented.

Numerical Calculation for Latent Heat and Thermal Expansion Coefficient of a Two Dimensional Hard Disk System

ZHAO Min, SUN Feng-Guo, TANG Rong-Qi

1993, 7(2): 152-155 . doi: 10.11858/gywlxb.1993.02.013

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Abstract:
Using numerical method of reference [6] , we calculated the latent heat and thermal expansion coefficient of a two dimensional hard disk system.

Study of Surface Morphology of Diamond Thin Films on Mo Substrates

YANG Guo-Wei, MAO You-De

1993, 7(2): 156-160 . doi: 10.11858/gywlxb.1993.02.014

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Abstract:
Diamond thin films have been deposited by the hot filament CVD method on molybdenum substrates from the mixture reactant gas of acetone and hydrogen. The surface morphology of the obtained diamond films under various deposition conditions, i. e. , different reaction pressures, was observed by scanning electron microscope (SEM). The experiment results strongly indicate that the surface morphologies of the resulting films have closely related to the reaction pressures. Under the lower reaction pressure, the grains consisting of the resulting films present mainly the morphology similar to that of the small single crystal cubo-octahedron and double small crystal grains. Under the higher reaction pressure, however, the surface morphology of the grains looks like the large cauliflower. These results indicated that there exist, different growth mechanisms for CVD diamond crystals under various deposition conditions finally, the structure of cauliflower-like diamond grains was been analyzed and the formation mechanism studied.

1993 Vol. 7, No. 2

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