高压物理学报

Cubic Silicon Nitride and Its Synthesis by Shock Wave Compression

HE Hong-Liang

2007, 21(1): 1-7 . doi: 10.11858/gywlxb.2007.01.001

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Abstract:
Cubic silicon nitride is a new polymorphous of Si3N4 synthesized under high pressure and high temperature. Compared to the two known hexagonal phases of and , the new phase is about 26% denser in density, and it is predicted to be a new multi-functional ceramic. The achievement and related concern of the cubic silicon nitride have been reviewed in this paper, including the progress in artificial synthesis, the study on its physical property, the synthesis of other Ⅳ(A) group denser nitrides (Ge3N4, Sn3N4, C3N4), and the explore of the possible post-spinel phase of nitride. By using a flyer impact technique with explosive detonation, we recently have synthesized the cubic silicon nitride from the precursor of -Si3N4, and the mass production of the cubic phase has reached about 2 grams in each run of the shock wave compression test, which provides an economic way for further investigation of its potential performance in industriy.

Equations of State for Fluid Hydrogen and Deuterium: Dissociation Effects Studies

TIAN Chun-Ling, JING Fu-Qian, GU Yun-Jun, CAI Ling-Cang, LIU Fu-Sheng

2007, 21(1): 8-14 . doi: 10.11858/gywlxb.2007.01.002

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Abstract:
Molecular hydrogen and deuterium under high temperature and high density conditions may undergo dissociation reaction, and thus transforms to an interacting mixture composed of molecules and atoms with complex interactions between constituent particles. In this paper, we use onecomponent fluid van der Waals (VDWLF) mixture approximation, in which an equivalent one-component potential is utilized to describe that compression behavior of such a mixture system in order to simplify the statistical thermodynamic treatment, and, therefore, calculate the internal energy and pressure of this system and concentration for each constituents through Helmholtz free energy minimization. The dissociation effects including temperature- and pressure-induced are studied in the density and temperature range of 0.6 g/cm3 (corresponding molar volume V3.3 cm3/mol) and T10 000 K, respectively. The calculated isothermal equations of state of hydrogen are basically in agreement with those calculated by the two-component fluid variational theory and the first principle molecular dynamics and Monte Carlo simulations. The calculated single shock and double shock Hugoniots for molecular deuterium are also in well accord with experiments. The above mentioned results demonstrate the VDWLF mixture approximation is valid for the compression behavior descriptions of hydrogen (deuterium) within the region of 0.6 g/cm3 (corresponding molar volume V3.3 cm3/mol) and T10 000 K.

High Temperature and High Pressure Synthesis and Study of 0212-Type Ca3Cu2O4+Cl2-y

YANG Da-Xiao, LIU Qing-Qing, GAO Wei-Bo, YU Wen, LI Feng-Ying, JIN Chang-Qing

2007, 21(1): 15-19 . doi: 10.11858/gywlxb.2007.01.003

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Abstract:
Using the apical oxygen doping mechanism, i. e. a partial substitution of divalence O for the monovalence Cl, we synthesized Ca3Cu2O4+Cl2-y with Ag2O under high temperature and high pressure. From X-ray diffraction composition analysis, we confirmed that Ca3Cu2O4+Cl2-y crystallizes into a 0212 structure. With increasing the content of Ag2O, we found that lattice parameters a shrinked but c increased. It suggested that it should be hole doping. We also investigated the temperature dependence of the electrical resistivity and DC magnetic susceptibility for two samples, but we didn't observe superconductivity. It maybe resulted from the too low density of hole carrier.

Experimental Study on the Microstructures and Dynamic Behavior of a PBX Substitute Material

ZHANG Peng, ZHAO Feng, BAI Shu-Lin, FU Bin, ZHANG Guo-Hua

2007, 21(1): 20-28 . doi: 10.11858/gywlxb.2007.01.004

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Abstract:
The microstructures and intrinsic defects engendered during the compression process of manufacture of a PBX substitute material D-90031, as well its dynamic behavior and failure mechanisms were studied. By using digital image treatment technique, in situ nano-indenter system, Split Hopkinson Pressure Bar (SHPB) and weight dropping tests, we obtained the features of microstructures, modulus and hardness of each constituent, dynamic properties, as well as the size distribution of pieces and failure modes. It was found that the grain shape changed with the applied compressive load, such as the grain was elongated along the direction vertical to the load application direction. The size distribution of pieces after impact meets a certain statistical rule. The results obtained are meaningful to deeply understand the relationship between the properties and microstructures of solid explosive.

Synchrotron Radiation of Different Nano Size ZnS Nanocrystalline under High Pressure Induced

PAN Yue-Wu, YU Jie, CUI Qi-Liang, GAO Chun-Xiao, ZOU Guang-Tian, LIU Jing

2007, 21(1): 29-34 . doi: 10.11858/gywlxb.2007.01.005

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Abstract:
In-situ energy dispersive X-ray diffraction (EDXD) on ZnS nanocrystalline was carried out under high pressure by using a diamond anvil cell (DAC). Phase transition of nano ZnS from wurtzite to rocksalt occurred at 16.0 GPa and 16.7 GPa for 10 nm and 3 nm sample, respectively, which were higher than that of the bulk materials. The structures of ZnS nanocrystalline at different pressures are built by using Materials Studio (MS) and the bulk modulus and the pressure derivative of ZnS nanocrystalline were derived by fitting the equation of Birch-Murnaghan. The resulting modulus was higher than that of the corresponding bulk material, indicating that nanomaterial possesses higher hardness than its bulk materials.

Investigation of Precursor Decay and Stress Relaxation in Shock-Compressed 20 Steel

WANG Yong-Gang, HE Hong-Liang

2007, 21(1): 35-39 . doi: 10.11858/gywlxb.2007.01.006

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Abstract:
The precursor decay and stress relaxation behavior of 20 steel under shock compression were studied using planar impact experiments with different sample thickness. Time resolved free surface velocity profile measurements are performed by means of a velocity interferometer system for any reflector (VISAR) with the time resolution of 1 ns. The results show an apparent decay in the Hugoniot elastic limit with increasing propagation distance, as well as a stress relaxation behind the elastic wave front, and nearly 44% loss of Hugoniot elastic limit was observed in the present sample thickness range. The rise time of elastic wave fronts as a function of the sample thickness has also been determined accurately. Experiments with different impact velocities are carried out, and indicate apparently the independence of the dynamic yield behavior on the loading stress amplitude.

Electrical Conductivity and X-Ray Diffraction Study of Iron under High Pressures

HUANG Wei-Jun, CUI Qi-Liang, BI Yan, ZHOU Qiang, ZOU Guang-Tian

2007, 21(1): 40-44 . doi: 10.11858/gywlxb.2007.01.007

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Abstract:
Four electrodes method and the magnetic sputter film deposition technique combined with photolithographic shaping method are used to measure the electrical resistance of iron up to 25 GPa. Furthermore, in-situ high pressure X-ray diffraction experiment was performed for measuring the lattice parameters of iron under high pressures up to 25 GPa. The experimental results indicated that the process of bcc-hcp phase transition of iron initiated at 13.7 GPa and finished at 18.1 GPa. The pressure dependence of electrical conductivity of iron was finally deduced from the resistance data and the X-ray diffraction results.

Equation of State and Phase Transition of (Mg0.92, Fe0.08) SiO3 Enstatite under Shock Compression and Its Geophysical Implications

YANG Jin-Ke, GONG Zi-Zheng, DENG Li-Wei, ZHANG Li, FEI Ying-Wei

2007, 21(1): 45-54 . doi: 10.11858/gywlxb.2007.01.008

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Abstract:
We performed shock wave experiments on a natural pyroxene with chemical composition close to (Mg0.92, Fe0.08)SiO3 and initial density of 3.06 g/cm3 at pressures between 48 and 140 GPa, using impedance match method and electrical probe technique. Considering McQueen et. al. data, it is obvious that (Mg0.92, Fe0.08)SiO3 goes through three phase regions in the procedure of shock compression: Low-pressure phase region (LPR), mixed phase region (MPR), and high-pressure phase region (HPR), corresponding to the pressure 0~40 GPa, 40~67 GPa and 68~140 GPa, respectively. In low-pressure phase region, the relationship between shock wave velocity D and particle velocity u was expressed by McQueen et. al. data. Then in high-pressure phase region (at pressures between 68 to 140 GPa), it can be described linearly from our experiment data. The calculated D-u relationship for the assemblage of (Mg0.92, Fe0.08)O(Mw)+SiO2(St) is significantly different from the experimental data, excluding the possibility of chemical decomposition of perovskite to oxides during the shock compression. The Grneisen parameter can be obtained by fitting the experimental data. Using the third-order Birch-Murnaghan finite strain equation of state, the shock experimental data yield a zero-pressure bulk modulus K0S=259.6(9) GPa and its pressure derivative K0S=4.20(5), with 0=4.19 g/cm3. A comparison of the experimental Hugoniot densities of perovskite with the PREM density profile prefers a perovskite-dominant lower mantle model.

Thermoelectric Properties of N-PbTe Doped with Sb2Te3 Prepared by High-Pressure and High-Temperature

SU Tai-Chao, ZHU Pin-Wen, MA Hong-An, REN Guo-Zhong, GUO Jian-Gang, IMAI Yoshio, JIA Xiao-Peng

2007, 21(1): 55-58 . doi: 10.11858/gywlxb.2007.01.009

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Abstract:
N-type PbTe compounds doped with Sb2Te3 have been prepared at high-pressure and high-temperature (HPHT). The thermoelectric properties of all the samples have been measured at room temperature. The Seebeck coefficients in absolute value and the electrical resistivities decrease with an increase of Sb2Te3 content dramatically first and then slowly. The thermal conductivity slight increases with an increase of the content of doping. The figure of merit, Z, increases first and then decreases and the maximum value reaches 8.710-4 K-1 which is much higher than that PbTe doped with PbI2 prepared at normal pressure. This result indicates that enhanced thermoelectric properties of PbTe can be obtained by the HPHT method with suitable dopant.

Plasticity Mechanism Associated with Nano-Void Growth under Impact Loading along 〈111〉 Direction in Copper

DENG Xiao-Liang, ZHU Wen-Jun, HE Hong-Liang, WU Deng-Xue, JING Fu-Qian

2007, 21(1): 59-65 . doi: 10.11858/gywlxb.2007.01.010

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Abstract:
Evolution of Nano-void (diameter d1.3 nm) in single crystal copper and associated plasticity deformation around the nano-void under impact loading are investigated by means of molecular dynamics (MD) simulation. The results of simulation reveal that in the tensile process there are three of all four {111} family planes to be activated to glide, dislocations are nucleated in the region near the void surface and then move outside on three {111} family planes as the void grows. The velocity of dislocation along 〈112〉 directions with the maximum resolve shear stress can exceed transverse sound velocity. The calculated dislocation damping constant is appropriately consistent with the experiment results. Due to the approximately symmetrical plastic deformation around the void, the shape of the void during growth process is almost spherical. The growth rate of the void radius is observed to be constant under constant shock strength, and the amplitude increases as well as the shock strength increases.

Experiment and Calculation of Output Current of Ferroelectric Ceramics in Parallel Connection Loaded by Shock Waves

CHEN Lang, TENG Xiao-Qin, LU Jian-Ying, FENG Chang-Gen

2007, 21(1): 66-70 . doi: 10.11858/gywlxb.2007.01.011

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Abstract:
To analyze the characters of out current of different number ferroelectric ceramics, the tests of PZT95/5 ferroelectric ceramics in parallel connection loaded by the shock waves were carried out. The output currents of ferroelectric ceramics for the resistance loads were measured. A model calculating the output current of ferroelectric blocks in parallel connection was developed. The currents under different number of ferroelectric blocks were calculated numerically with this model. By comparing the calculated results and experimental results, the effects of the number of ferroelectric and shock wave on output of current were analyzed. The results indicated that if the planar shock waves load the ferroelectric blocks, the shape of the output current will be quadrate and the current will increase along with the number of the ferroelectric blocks increasing. The shape of shock waves and the sparse waves influence on the output current and the depolarization ratio.

2D Numerical Simulation of Spallation in Three Steels with the Damage Function Model

PEI Xiao-Yang, LI Ping, DONG Yu-Bin

2007, 21(1): 71-76 . doi: 10.11858/gywlxb.2007.01.012

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Abstract:
A damage function model is implemented in 2D finite element code-DEFEL, with which the simulation of plate surface spallation testing is performed by using the material parameters of three type steel, HR-2, 2169 and 45. The effect of strain-hardening and Bauschinger are taken into account. The calculated free-surface velocity-time relation curves are consistent with the experimental results. The damage distribution and its development in the spalled layers are also given from the numerical results. The spall strength of materials from simulation is higher than that from acoustical approximation, but lower than theoretical spall strength. The analysis of the differences among them shows that the simulation is reasonable.

Experimental Study on Detonation Characteristics of Several Liquid Fuel-Air Clouds in Shock Tube

YAO Gan-Bing, XIE Li-Feng, LIU Jia-Cong

2007, 21(1): 77-82 . doi: 10.11858/gywlxb.2007.01.013

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Abstract:
The detonation characteristics of fuel (PO, IPN, C5~C6, hexane, heptane, Decane)-air cloud were studied in shock tube. The critical initiation energy was measured by the up and down method and cell size by smoked metallic foil. The comparison of detonation characteristics among these fuels was also carried. Results demonstrate that the relationship of critical initiation energy and equivalence ratio shows an U shape curve, the minimal critical energy is obtained when equivalence ratio is slightly larger than 1. The conclusion is similar to the gaseous detonation. These experimental results help us deeply understanding the detonation nature of hydrocarbon-air mixtures.

Dynamic Behavior of Ta-Nb Alloy under Shock Compression

HUA Jin-Song, GU Yan, ZHANG Shi-Wen, WANG Peng-Lai, FENG Dong-Sheng

2007, 21(1): 83-88 . doi: 10.11858/gywlxb.2007.01.014

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Abstract:
A new kind of Ta-Nb alloy has been studied. By means of ultrasonic measurement, its sound velocities of longitudinal wave and transverse wave were obtained, and some of its static mechanical parameters were calculated. Through shock compression experiments with a two stage gas gun, its shock Hugoniot curve in pressure range from 60 GPa to 196 GPa was obtained. The result was in good agreement with the calculation by a mixture model. The mechanical characteristics of Ta-Nb alloy with two kinds of tungsten alloy have been compared, which shows the dynamic behavior of Ta-Nb alloy is better than that of tungsten alloy.

Influence of Combined Treatment of Ultra High Pressure and Enzyme Inhibitors on Peroxidase and Pectin Methyl Esterase in Litchi Pulp

HUANG Li, SUN Yuan-Ming, CHEN Bai-Nuan, HUANG Wei, ZHAN Guo-Lian

2007, 21(1): 89-94 . doi: 10.11858/gywlxb.2007.01.015

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Abstract:
In order to investigate the effects of combined treatment of ultra high pressure (UHP) and enzyme inhibitors on the activities of peroxidase (POD) and pectin methyl esterase (PME) in litchi pulp, two kinds of enzyme inhibitor prescriptions were designed including group A (citric acid 5 g/L+L-ascorbic acid 2.5 g/L+calcium chloride 5 g/L) and group B (citric acid 10 g/L+L-ascorbic acid 5 g/L +calcium chloride 10 g/L). After being immersed in enzyme inhibitor solutions for 10 min, the pulp of litchi (Litchi chinensis Sonn cv. Huaizhi) was subjected to UHP treatment (100~400 MPa for 30 min at 10 ℃). The activities of POD and PME were detected by spectrophotometry. Results showed that separate treatment of group A or group B could lead to obvious passivation of POD and prominent activation of PME. Combined treatment of UHP and group A could not make the activities of POD and PME decrease. The influence of combined treatment of UHP and group B on POD and PME had relevance to pressure value, the POD activity lowered when the combined treatment of 100~300 MPa and group B was applied, and the PME activity raised obviously when the combined treatment of 200~400 MPa and group B was applied. So, combined treatment of UHP and enzyme inhibitors had certain synergistic effect for POD inactivation, and the synergistic inhibition effect would be more obvious with higher concentration of enzyme inhibitors; but combined treatment of UHP and enzyme inhibitors showed certain rivalry for PME inactivation.

Effect of High Pressure on Exoproteinase of Bacillus subtilis

XIE Hui-Ming, HUANG Xun-Duan, PAN Jian, ZENG Qing-Mei, WANG Hai-Xiang, JIANG Ye-Lei

2007, 21(1): 95-102 . doi: 10.11858/gywlxb.2007.01.016

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Abstract:
We studied the effect of high pressure process (HPP) on exoproteinase of Bacillus subtilis by using Box-Behnken response surface methodology. Experimental results showed that HPP could inhibit activity of exoproteinase significantly. In the course of treatment, pressure and temperature were key factors to passivate enzyme, and their interaction was notable. A model of exoproteinase passivation was established by design expert software, which determination coefficient was 0.974 7 and adjusted determination coefficient was 0.942 1. Analysis of variance implied that the model was significant. Therefore, the model could be used to analyze and predict. Additionally, the experiment indicated that exoproteinase activity correlated with lethal rate significantly (R=0.933 0). The exoproteinase could be regarded as an index to evaluate effect of HPP on microorganism.

Calculational Model and Application of Acceleration of Projectile in Bore about DAVIS Gun Experiment

DUAN Ji-Yuan, LIU Cang-Li, WANG Yan-Ping, YU Chuan

2007, 21(1): 103-107 . doi: 10.11858/gywlxb.2007.01.017

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Abstract:
Aimed at idiographic structure of DAVIS gun, for accurately calculating acceleration of projectile in bore, this article emulationally calculated the launch of a DAVIS gun through classical interior ballistics, acquired the interior ballistic parameters-time curves and educed the acceleration-time curve of projectile according to bore pressure-acceleration relation. The calculated results accorded with the experimental data.

Damage and Cracking of Zr41Ti14Cu12.5Ni10Be22.5 Bulk Amorphous Alloy under Planar Shock Compression

LI Qiang, YANG Chao, ZHAN Zai-Ji

2007, 21(1): 108-112 . doi: 10.11858/gywlxb.2007.01.018

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Abstract:
Planar shock compression effects on damage and cracking in Zr41Ti14Cu12.5Ni10Be22.5 bulk amorphous alloy are studied using a two-stage light gas gun. The experimental result indicates that the cracking angel of bulk amorphous alloy under planar shock compression is smaller than that of traditional compression experiment, it is decided by the highest strain velocity under shock compression conditions in bulk amorphous alloy; part of bulk amorphous alloy surface also is melt by the effects of highest strain velocity and the energy of partial adiabatic shear bands; the crystallization happens in bulk amorphous alloy by the effects of temperature and pressure.

2007 Vol. 21, No. 1

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