高压物理学报

Synchrotron Radiation Diffraction of Gallium Oxide under High Pressure

CUI Qi-Liang, TU Bao-Zhao, PAN Yue-Wu, WANG Cheng-Xin, GAO Chun-Xiao, ZHANG Jian, LIU Jing, ZOU Guang-Tian

2002, 16(2): 81-84 . doi: 10.11858/gywlxb.2002.02.001

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Abstract:
The in-situ synchrotron radiation diffraction of gallium oxide under high pressure has been studied in the range of 0～42.5 GPa with diamond anvil cell (DAC), using methanol-ethanol-water (16∶3∶1) mixture as transmission medium. We have found that under room temperature, the monoclinic gallium oxide turns into a rhombohedral one under 13.3 GPa. After the phase changs, the Ga ions are only at the centers of the octahedrons instead of their original locations which are at both the centers of the octahedrons and the tetrahedrons. When the pressure goes back to ambient pressure, the sample turns back to monoclinic structure.

High-Pressure and High-Temperature Synthesis of the Electron-Doped Layered Magnates La2-2xCa1+2xMn2O7

ZHU Jia-Lin, YU Ri-Cheng, LI Feng-Ying, JIN Chang-Qing

2002, 16(2): 85-93 . doi: 10.11858/gywlxb.2002.02.002

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Abstract:
The electron-doped layered magnates with nominal composition La2-2xCa1+2xMn2O7 (x=1.0～0.8) were prepared using a standard solid-state reaction method at a temperature of 1 260 ℃ and a pressure of 5 GPa. The structures of the compounds were investigated using powder X-ray diffraction and Rietveld analysis. The results show that all structures of the samples belong to the Sr3Ti2O7 tetragonal structure with space group of I4/mmm. With the electron concentration increasing, the MnO6 octahedral deformation and the value of the lattice volume increased. Meanwhile, Neel temperature TN and magnetization of the samples increased with the La3+ introduction. The resistivities also increased due to the weakening of double-exchange interaction. No magneto resistance effect was observed in the temperature range of measurement.

Penetration and Perforation of Thick Metallic Targets under Impact by Missiles

WEN He-Ming

2002, 16(2): 94-104 . doi: 10.11858/gywlxb.2002.02.003

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Abstract:
Simple analytical equations are given in this paper to predict the penetration and perforation of thick metallic targets under normal impact by missiles with different nose shapes over a wide range of impact velocities. In the formulation, it is assumed that the deformations are localized and that the impact energy is dissipated only by penetration. It is further assumed that the mean pressure offered by the target materials to resist the missiles consists of two parts. The first is a cohesive quasi-static resistive pressure due to the elastic-plastic deformation of the target materials based upon a cavity expansion formula. The second is a dynamic resistive pressure defined as a velocity-dependent enhancement factor applied to the quasi-static resistance. Equations are derived for predicting the D. O. P. (Depth of Penetration) in the targets and the ballistic limits in the case of perforation. It transpires that the model predictions are in good agreement with experimental data for a wide range of metallic targets struck transversely by missiles with different nose shapes over a wide range of impact velocities.

Analysis of Equivalence for Structural Response Induced by Pulsed X-Ray with Other Analogue Sources

PENG Chang-Xian

2002, 16(2): 105-110 . doi: 10.11858/gywlxb.2002.02.004

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Abstract:
The equivalence of structural response induced by pulsed X-ray with analogues of electron beam and explosion are analyzed. The measured results of structural response in aluminum alloy cylindrical shells subjected to pulsed X-ray and MDF explosion are used in quantitative analyses of equivalence. The fairly good results of equivalence are obtained.

Detonation Reaction-Zone Structure of JB-9014

ZHAO Tong-Hu, ZHANG Xin-Yan, LI Bin, WANG Gui-Chao

2002, 16(2): 111-118 . doi: 10.11858/gywlxb.2002.02.005

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Abstract:
The structure of reaction-zone of JB-9014 explosive was investigated using photoelectric technique. For one dimensional steady detonation wave of JB-9014 (1.894 g/cm3), the Neumann spike pressure is 36.5 GPa, the width of reaction-zone is 1.75 mm, and the period of reaction is 0.31 s. It was found that the width of reaction-zone and the period of reaction decrease with explosive density.

p-V Characteristics of Sintered Porous Mo under Hydrostatic Pressure

SUN Yue, LIU Fu-Sheng, GAO Zhan-Peng, ZHANG Qing-Fu

2002, 16(2): 119-124 . doi: 10.11858/gywlxb.2002.02.006

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Abstract:
Loading-unloading experiments on mid-density sintered porous Mo specimen were conducted under hydrostatic pressure. Under the circumstance, the p-V characteristics of foamed material with different diameters and initial density were first studied. Certain evidences show that strain amplitude in samples is correlated with initial density; but unload curves do not depend on initial density and diameter of specimens. Foamed Mo samples appear have higher energy absorbing capacity and efficiency based on calculated results. However, both the excellence relate to energy are somehow decreased after pre-pressured to the specimens.

Preparation of W-Mo Composites and Their Characteristic Wave Impedance

SHEN Qiang, DOU Jin-Feng, ZHANG Lian-Meng, HUA Jing-Song, TAN Hua

2002, 16(2): 125-130 . doi: 10.11858/gywlxb.2002.02.007

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Abstract:
Dense W-Mo composites with different mass fractions of W and Mo were prepared at same temperature (1 473 K) and pressure (30 MPa) by using spark plasma sintering technique. The transverse and longitudinal wave velocities of the samples were accurately measured using ultrasonic pulse echo overlap method, so the characteristic wave impedance values of the samples were then obtained. The results of phase composition and electron probe microscope analysis show that the W-Mo composite can be treated as a mechanical mixture system and high coherence between W and Mo grains is achieved due to sintering additives. Therefore, ideal mixture model was adopted to estimate the characteristic wave impedance of W-Mo composites. Comparisons with the experimental results demonstrate that the suggested model is sufficiently accurate to predict the wave impedance value of W-Mo composites.

Shock Wave Crystallization of Amorphous Alloys FeSiB, FeMoSiB and FeCuNbSiB

ZHAO He-Yun, KAN Jia-De, WANG Hai, LIU Zuo-Quan

2002, 16(2): 131-136 . doi: 10.11858/gywlxb.2002.02.008

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Abstract:
Shock wave and annealing crystallization of amorphous alloys FeSiB, FeMoSiB and FeCuNbSiB were investigated by isothermal and non-isothermal DSC technique. It is found that shock wave crystallization is very perfect (fraction crystallized is very close to 100%) though the period of crystallization is very short, only about 10-6～10-8 of annealing's. Produced phases are different from the parent phase in structure and composition, shock wave crystallization is similar to the diffusion solid state phase transition in form, however, it is very difficult to explain the high velocity of transformation by the diffusion theory of solid state phase transition. Shock wave crystallization of amorphous alloy is a new method.

Electrical Properties and Phase Transition of Sr2FeMoO6 under High Pressure

ZHAO Pan, BAO Zhong-Xing, LIU Cui-Xia, LI Feng-Ying, LIU Zhen-Xing, JIN Ming-Zhi, YU Ri-Cheng, JIN Chang-Qing

2002, 16(2): 137-139 . doi: 10.11858/gywlxb.2002.02.009

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Abstract:
The resistance-pressure and capacitance-pressure relationships for double perovskite material of Sr2FeMoO6 at room temperature and up to 20 GPa were studied using a diamond anvil cell. The experimental results show that Sr2FeMoO6 (a kind of half-metal material) undergoes metallic transition at about 2.1 GPa. We believe this transition is related with electronic structure transition under high pressure.

Thermodynamic Study on Passivation Reaction of Uranium with Supercritical Fluid CO2

XUE Wei-Dong, ZHU Zheng-He, CHEN Chang-An, ZOU Le-Xi, SUN Ying, ZHANG Guang-Feng, WANG Xiao-Lin

2002, 16(2): 140-146 . doi: 10.11858/gywlxb.2002.02.010

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Abstract:
The passivation process of supercritical CO2 fluids on the surface of metallic uranium was calculated. The results show that the change of Gibbs free enthalpies of the substances in passivation layer decreases with elevated temperature, and that the increased pressure facilitates the formation of passivation layer.

Particle Simulation on Plasma Bubble and Energetic Ion Generation Produced by Laser

MA Yan-Yun, CHANG Wen-Wei, YIN Yan, CAO Li-Hua, YUE Zong-Wu

2002, 16(2): 147-151 . doi: 10.11858/gywlxb.2002.02.011

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Abstract:
The interaction between high power S-polarized laser and overdense plasma was investigated numerically using a 2.5 D particle code PLASIM. Both electron caviton and plasma ripple appear and the latter is just like bubbles. Ions are accelerated in the front of the bubbles, whose relativistic kinetic energy can reach 72 MeV. The distribution of energetic ions was also studied.

Shock Wave Physics: The Coming Challenges and Exciting Opportunities in the New Century－Introduction of the 12th International Conference of Shock Compression of Condensed Matter (SCCM-2001)

GONG Zi-Zheng

2002, 16(2): 152-160 . doi: 10.11858/gywlxb.2002.02.012

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Abstract:
The 12th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter (SCCM-2001) was introduced. Papers presented in SCCM-2001 were surveyed and the recent progresses on shock compression of condensed matter were retrospected. The basic paradigms and the great achievements of the physics and mechanics of condensed matter at high dynamic pressure and stress were surveyed and revaluated. The coming challenges and exciting opportunities of shock wave physics in the 21 century were prospected.

2002 Vol. 16, No. 2

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