高压物理学报

Pressure Effects on the Behavior of Helium in Niobium

LIU Zhi-Ming, CUI Tian, HE Wen-Jong, ZOU Guang-Tian, WEI Meng-Fu, CHEN Chang-An

2008, 22(3): 225-231 . doi: 10.11858/gywlxb.2008.03.001

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Abstract:
By combining pseudopotential plane-wave method at 0 K with Car-Parrinello molecular dynamics at finite temperature, the behavior and aggregation of helium in niobium are simulated under different pressures. The result shows that the closed-shell helium atom plays a role of rigid-ball such that to destroy local metallic bonds of niobium and push away the near free electrons. Under ambient pressure and room temperature, locally high concentrated helium atoms immigrate towards the vacancy site, resulting in helium bubbles. The same helium density of He will dislocate Nb atom, forming an interstitialvacancy pair for the helium bubble formation. Under high pressures up to 40 GPa, no bubble is observed in perfect Nb host lattice due to the failure of interstitial-vacancy formation.

The Electrodes Factor of Accurate Resistivity Measurement with Four-Point Probe Method in a Diamond Anvil Cell

WU Bao-Jia, HAN Yong-Hao, CUI Xiao-Yan, LIU Cai-Long, WANG Yue, PENG Gang, GAO Chun-Xiao

2008, 22(3): 232-236 . doi: 10.11858/gywlxb.2008.03.002

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Abstract:
To figure out the effect of electrode resistivity on the in situ resistivity measurement with four-point probe method in a diamond anvil cell (DAC), the authors simulated the distribution of the steady electric field in the sample with finite element analysis (FEA). It reveals that the electrode resistivity smaller than the sample resistivity too much would result in a large measurement error, and therefore indicates that reducing the resistivity difference between the electrode and sample can improve the measurement accuracy.

Experimental Study on Electrical Conductivity of Biotite- and Plagioclase-Bearing Gneiss at High Temperature and High Pressure

HUANG Xiao-Ge, BAI Wu-Ming, ZHOU Wen-Ge

2008, 22(3): 237-244 . doi: 10.11858/gywlxb.2008.03.003

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Abstract:
We have investigated the electrical properties of rock sample from Yinshan orogenic zone by in situ complex impedance spectroscopy using a multianvil apparatus. The electrical conductivity was measured at pressure of 1 GPa and temperature from 250 ℃ to 1 100 ℃ at frequencies from 0.1 Hz to 1 MHz. The data of resistance were obtained by using an equivalent circuit fitting technique. From these measurements we determined the electrical conductivity of the Archean metamorphic biotite- and plagioclase-bearing gneiss. The experimental results indicate that (1) each spectrum consists of an almost semicircular high-frequency arc Ⅰand a depressed high-frequency arc Ⅱ.The impedance spectrum Ⅰ is dominated by grain-interior response; the impedance spectrum Ⅱ is dominated by the sample-electrode interface impedance. (2) Electrical conductivity displays Arrhenian behavior respectively over investigated temperature range from 250 ℃ to 700 ℃ and from 750 ℃ to 1 100 ℃. However, it rapidly increases from 700 ℃ to 750 ℃. This jump is due to dehydration-melting of biotite within sample based on the comparative analysis of SEM photoes and electron probe data for pre-run and post-run samples. (3) Over higher temperature range (750~1 100 ℃), sodium is the dominating charge carrier in partially molten samples. (4) The activation energy of biotite- and plagioclase-bearing gneiss is 0.53 eV over range of temperature from 250 ℃ to 700 ℃. However, the activation energy of partially molten sample is 1.41 eV over range of temperature from 750 ℃ to 1 100 ℃. This change of activation energy has relations with sodium content and mobility in melt. It is possibly due to the change of structure between mineral and melt within samples.

Numerical Simulation and Analysis of the Penetration of Tungsten-Alloy Long Rod into Semi-Infinite Armor Steel Targets

LAN Bin, WEN He-Ming

2008, 22(3): 245-252 . doi: 10.11858/gywlxb.2008.03.004

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Abstract:
Numerical simulation of the penetration of tungsten alloy long rod into semi-infinite armor steel targets is performed with ALE method and Steinberg constitutive model coupled in ANSYS/LS-DYNA finite element code. The configurations of four different phases in the penetration process and the changes of relevant physical parameters with time are given. The distribution of pressure, particle velocity and the material flow characteristics of both the penetrator and the targets are analyzed. It is revealed that the numerically predicted depth of penetration is in good agreement with available experimental results and that the behavior of materials adjacent to the interface of penetrator and targets is controlled mainly by the hydrostatic pressure.

Mechanical Properties of Transition-Metal Osmium under High Pressure

LIU Xiao-Mei, LIANG Yong-Cheng, SONG Qiu-Hong

2008, 22(3): 253-258 . doi: 10.11858/gywlxb.2008.03.005

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Abstract:
The equation of states, elastic constants and other mechanical properties of transition-metal osmium under high-pressure are studied by the first-principles plane-wave pseudopotential calculations based on the density functional theory (DFT). The calculated results indicate that osmium has high bulk modulus B0 (423.9 GPa) and large elastic constants C11 (771.3 GPa) and C33 (852.0 GPa) comparable to diamond (B0=452.8 GPa, C11=C33=1 082.9 GPa), so it is an ultralow-compressible material. However, its elastic constant C44 (269.8 GPa) and shear modulus G (276.8 GPa), which indirectly measure hardness, are half of those of diamond (C44=586.9 GPa, G=537.5 GPa). Because of its pure metallic bonds, it may not be superhard material. The microscopic mechanism of high bulk modulus and low hardness can be understood from the analysis for electronic structures, and it helps to design and synthesize new superhard material.

High Pressure-Induced Changes of Physico-Chemical Properties and Mutagenesis in Aspergillus Oryzae

WANG Hua, SHEN Si-Le, LI Zhi-Hui, CUI Hang, WANG Yan-Feng, FU Xin-Xin, YANG Fan, CHANG Liang, ZHENG Xiao-Yi, ZOU Guang-Tian

2008, 22(3): 259-264 . doi: 10.11858/gywlxb.2008.03.006

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Abstract:
In order to study the pressure-induced changes of biological and physiochemical properties in fungi, Aspergillus Oryzae was treated with high pressure at 0.1~400 MPa for 20 min, and their viability and modality, as well as the activity of protease and amylase were determined. The result showed that high pressure induced obvious changes in the viability and modality of Aspergillus Oryzae. The activities of protease and amylase in Aspergillus Oryzae showed a specific regular pattern upon high pressure treatment. In the pressure range of 0.1~200 MPa, the protease activities decreased, but enhanced gradually in the range of 200~400 MPa. The protease activity was larger than control strain after treatment fungi with 300 MPa or higher, and reached the maximal at 400 MPa. The activity of amylase also decreased with pressure in the range of 0.1~100 MPa and gradually enhanced in the range of 100~200 MPa, and subsequently decreased again at the range of 200~400 MPa. The activity of amylase is highest in the treatment with 200 MPa, and same as control strain at 400 MPa. A fine mutant strain of fungi, HP300a, was obtained after treatment with 300 MPa. HP300a has a series of excellent characteristic: quick growth, more spores, higher activity of protease, and is rarely polluted by other strains. In addition, several indexes of soy sauce brewaged by HP300a were much better than that by control strains.

Investigation on Grain Boundaries and Related Abradability of Diamond Thick Films

JIANG Zhi-Gang, FENG Yu-Ling, ZHENG Tao, LI Hong-Dong, LI Bo, ZHENG Yan-Bin, LIN Zhi-Wei

2008, 22(3): 265-268 . doi: 10.11858/gywlxb.2008.03.007

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Abstract:
The polished cross-section of the diamond thick films deposited by direct current glow discharge plasma was etched by hydrogen microwave plasma. The grain boundaries and the defects in the films have been directly observed using scanning electron microscopy (SEM). It is found that the non-diamond impurities, and the holes normally appear along the grain boundaries; and at high (low) methane flow rate corresponding to the constant hydrogen flow rate, the films consist of high (low) density of grain boundaries with netted texture.

Numerical Simulation for Rayleigh-Taylor Instability Using Runge-Kutta Discontinuous Finite Element Method

CHEN Er-Yun, LE Gui-Gao, MA Da-Wei, ZHAO Gai-Ping, ZHAO Ji-Yong

2008, 22(3): 269-274 . doi: 10.11858/gywlxb.2008.03.008

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Abstract:
Rayleigh-Taylor instability problem is simulated by using discontinuous finite element method which is developed for Euler equations with an additional body force corresponding to the gravity. Level set method for capturing moving interfaces and ghost fluid method with Isobaric fix for disposing the interfaces are used. Through two representative numerical examples of Rayleigh-Taylor instability, it can be concluded that this method has capability to solve multi-media fluid problems including contact discontinuous, without numerical oscillation near the interface and high resolution.

Study on 3D Computational Method by Coupling SPH Algorithm to Rigid Body Solution

LIANG Long-He, DONG Shi-Shun, WANG Zheng

2008, 22(3): 275-280 . doi: 10.11858/gywlxb.2008.03.009

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Abstract:
The 3D computational method and technique were studied by coupling SPH algorithm to rigid body solution. Based on the new method and technique, and combining with the Johnson-Cook, Johnson-Holmquist contitutive models, as well as the existing 3D synthetical Lagrangian finite element code CL3D, a new 3D Lagrangian code CRSPH3D was written out. The new code, CRSPH3D, is suitable to be used in the numerical simulation of the 3D problems of rigid projectile penetrating thick targets. The new code was applied to numerically simulate the processes of both rigid projectiles normally and obliquely impacting and perforating aluminum targets and rigid projectiles normally and obliquely impacting and penetrating thick concrete targets. For the problems of projectiles perferating aluminum targets, the simulation results gave good agreement to the experimental ones. And for the problems of projectiles penetrating concrete targets, the obtained results from simulations were qualitatively reasonable.

Acoustic Velocity of Water under High Temperature and High Pressure: Validity of the Equation of State of Water

LI Fang-Fei, CUI Qi-Liang, LI Min, ZHOU Qiang, ZOU Guang-Tian

2008, 22(3): 281-285 . doi: 10.11858/gywlxb.2008.03.010

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Abstract:
The knowledge of the thermodynamic equation of state of fluid water plays an important role in understanding of many phenomena within the purview of the earth and planetary sciences. However, data are sparse in the high temperature and high pressure region and most equations of state for water, at high pressures, rely heavily on extrapolation of data or calculations of molecular dynamics. This paper presents the acoustic velocity of water measured by Brillouin scattering technique at different temperature and pressure, and compares the velocity with those predicted by the equations of state. Our measured velocities of water are lower than those predicted by Saul and IAPWS-95, while they are the same as those predicted by Abramson within 6.0 GPa and 673 K; on the other hand, at 21 GPa and 890~1 100 K conditions, the measured velocities are higher than those predicted by all the three equations of state.

The Velocity and Elastic Constants in Fluid Oxygen under High Pressures and High Temperature

LI Min, CUI Qi-Liang, LI Fang-Fei, ZHOU Qiang, WU Xiao-Xin, ZOU Guang-Tian

2008, 22(3): 286-290 . doi: 10.11858/gywlxb.2008.03.011

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Abstract:
We applied the Brillouin scattering and diamond-anvil cell (DAC) technique to study the liquid oxygen at high pressure and high temperature. The singlefrequency green (532 nm) laser was used as Brillouin excitation source, and the Brillouin spectra were collected by a newly developed 3+3 pass tandem Fabry-Perot interferometer. The sample was loaded into a modified Merrill-Bassett-type four-screw DAC and heated externally by a resistance heater. The backscattering and 60 scattering geometries were used simultaneously. In this paper, we presented the pressure dependences of sound velocities of liquid oxygen under high pressure and high temperature, and the results were consistent with those predicated by theoretical calculations. The elastic constants of liquid oxygen were determined under high pressure and high temperature, we suspected that the volume of liquid oxygen doesn't expend with temperature under the pressure range from 2.3 GPa to 4.9 GPa.

Numerical Method of Simulating Underwater Explosion on Unstructured Moving Grids

WANG Bing, XU Hou-Qian, TAN Jun-Jie

2008, 22(3): 291-297 . doi: 10.11858/gywlxb.2008.03.012

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Abstract:
The computation of underwater explosion model with a gas-water interface is discussed where the interface is considered as a special internal boundary. This boundary is represented as doubled-defined points and each point corresponds to one material. The HLLC (Harten, Lax, van Leer, Contact) scheme is implemented in solving ALE (Arbitrary Largrangian-Eulerian Method) formulation on unstructured moving grids to track the material interface. This method is used to compute 1D spherical symmetric underwater explosion model and the solution agrees with the experiment data well. As an expansion, 2D cylindrical underwater explosion model is also computed and a satisfying result is obtained.

Two-Dimensional Numerical Simulation of Gas/Liquid Interface Instability

WANG Tao, BAI Jing-Song, LI Ping

2008, 22(3): 298-304 . doi: 10.11858/gywlxb.2008.03.013

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Abstract:
On the basis of multi-fluid volume fraction (VOF) and piecewise parabolic method (PPM), a multi-fluid hydrodynamic program MFPPM (Multi-Fluid Piecewise Parabolic Method) was developed and performed to study the Richtmyer-Meshkov instability of gas/liquid interface. The influences of initial perturbations and grids on the fluid mixing zone (FMZ) were mainly researched when it is accelerated by shock waves, and the FMZ width, bubble and spike height growing with time were presented simultaneously. By comparing the computational results, it shows that the initial perturbations affect the FMZ growth rate extremely,especially at late times. The evolution of spike is similar to the FMZ, the bubble height increases linearly with time basically, and influenced little by initial perturbations, but the configuration is quite different, and as the effect of grid size is.

X-Ray Diffraction Investigation of Pyrope under Pressure

MA Yan-Mei, PENG Gang, LI Min, LI Xue-Fei, GAO Ling-Ling, CUI Qi-Liang, ZOU Guang-Tian

2008, 22(3): 305-308 . doi: 10.11858/gywlxb.2008.03.014

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Abstract:
The in situ angle dispersive X-ray powder diffraction of natural pyrope collected from Zhenyuan in China using synchrotron radiation has been measured under high pressure (0~ 25.3 GPa) conditions with diamond anvil cell (DAC). We have not found any convincing evidence for a phase transformation in the experimental pressure range. The XRD patterns were then refined by using the refinement module combined in the Materials Studio program. We fit the Birch-Murnaghan equation of state and obtained its ambient pressure bulk modulus B0=199 GPa (B0=4).

Field Emission Characteristics of Boron Nitride Film Deposited on Dimond Film Substrate

LIU Li-Hua, LI Ying-Ai, GU Guang-Rui, ZHAO Yong-Nian

2008, 22(3): 309-312 . doi: 10.11858/gywlxb.2008.03.015

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Abstract:
Boron nitride (BN) thin film on diamond film substrate was synthesized by radio frequency (rf) magnetic sputtering physical vapor deposition. The field emission characteristics of diamond film and BN coated diamond film were measured in an ultrahigh vacuum system. Experiments demonstrate that BN film is effective in improving the field emission characteristics of diamond film. The threshold electric field is 12 V/m and highest emission current density is 272 A/cm2 for the BN coated diamond film. The Fowler-Nordheim plots show that electron emission is due to tunneling over a barrier.

Shock Synthesis of PZT 95/5 Powder by Planar Devices

TENG Hua, YANG Shi-Yuan, HE Hong-Liang, TANG Jing-You, WANG Jun-Xia

2008, 22(3): 313-317 . doi: 10.11858/gywlxb.2008.03.016

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Abstract:
Homogeneous submicron PZT 95/5 powder was synthesized from the mixtures of Pb3O4, ZrO2 and TiO2 with Nb2O5 as an additive by a planar shock wave loading device. The impact velocities of flyer plates on sample targets were adjusted by their thickness to obtain different shock conditions and to achieve the synthesis of PZT 95/5 powders in experiments. The analyses of XRD and SEM show that the shock-synthesized samples obviously became fine, and heavy distortion and many defects of lattices were formed in the process of shock compression.

Effect of High Pressure and Heat Treatment on Microstructure of Aluminum Bronze

YANG Jing-Ru, LIU Lin, REN Yan-Jun, LIU Jian-Hua, ZHANG Rui-Jun

2008, 22(3): 318-322 . doi: 10.11858/gywlxb.2008.03.017

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Abstract:
The effects of high pressure and heat treatment on microstructure of aluminum bronze were investigated by means of metallographic, scanning electronic microscope (SEM)/energy disersive spectrometer (EDS) and X-ray diffraction (XRD). Results showed that the grain size of phase in the aluminum bronze after the treatment at 750 ℃ and 6 GPa high pressure is smaller than that after treatment at 750 ℃ and normal pressure. When the aluminum bronze was treated at 750 ℃ and 6 GPa and followed by a treatment at 750 ℃ for 2 min, thin stripy phase occurred in the aluminum bronze, and its amount increased but the amount of granular phase decreased with increase of the cooling rate.

Primary Research on Side Pressure of Cylindrical TNT at Underwater Explosive Close-Field

ZHAO Ji-Bo, TAN Duo-Wang, LI Jin-He, ZHANG Guang-Sheng, ZENG Hua-Long

2008, 22(3): 323-328 . doi: 10.11858/gywlxb.2008.03.018

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Abstract:
According to the non-sphericity characteristic of shock wave surface at close-field after cylindrical charge with end boost exploring under water, the propagation of shock near-field is recorded by frame camera within 36 s after blasting, and the shape of shock on diverse time and situation is analyzed. The shock pressure of arbitrary point on the side of charge is measured through two streak cameras. Combined with the Rankine-Hugoniot relation, the pressure on shock front is gained, and the resolution is compared with LS-DYNA numerical value. It demonstrated that they are consistent relatively.

Calculation of the Hugoniot of Unreacted Explosives

FU Hua, LI Jin-He, TAN Duo-Wang, LI Tao

2008, 22(3): 329-332 . doi: 10.11858/gywlxb.2008.03.019

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Abstract:
With considering unreacted explosives as composite and porous materials media, the shock Hugoniot of several typical explosives are calculated by using plus principle and calculation method of the Hugoniot of porous materials. The calculation results are in good agreement with the experimental data.

The Behavior of Diaspore under High Pressure and High Temperature

LI Ming, LI Li-Xin, YANG Wu-Ming, ZHANG Pei-Feng, GAO Chun-Xiao, HE Chun-Yuan, HAO Ai-Min, LI Yan-Chun, LI Xiao-Dong, LIU Jing, et al

2008, 22(3): 333-336 . doi: 10.11858/gywlxb.2008.03.020

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Abstract:
The high heat conductivity and the high temperature carbonization of diamond make it difficult to achieve high temperature on diamond anvil cell, and the temperature in sample chamber is difficult to control accurately. Here we used sputtered alumina film as heat resistant layer, and an experiment at high pressure and high temperature was performed for diaspore on diamond anvil cell. Most previous experiments about diaspore for structure studying were performed at ambient temperature, and few reports of high temperature experiments were found. The changes of lattice parameters and compressibility of a-, b- and c- axis were investigated. The disputed bulk modulus was obtained by combining the experimental and computational results, and the bulk modulus of sample at high temperature and ambient temperature was compared.

2008 Vol. 22, No. 3

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