高压物理学报

A New Material for High-Pressure Anvil: Moissanite Gemstone

XIE Hong-Sen, XU Ji-An, ZHOU Wen-Ge

2004, 18(1): 1-3 . doi: 10.11858/gywlxb.2004.01.001

PDF (850)

Abstract:
History, synthesis method and main physical parameters of moissanite gemstone are described. Comparing to other synthetic gemstone (such as corundum, cubic zirconia), the moissanite gemstone is suitable for high-pressure anvil. The advantages and prospects of moissanite anvil cell for high-temperature and ultrahigh-pressure experiments studies are reviewed.

The High Pressure Synthesis and Properties of Apical Oxygen Doped High Tc Superconductors

JIN Chang-Qing

2004, 18(1): 4-9 . doi: 10.11858/gywlxb.2004.01.002

PDF (904)

Abstract:
The (Sr,Ca)n+1CunO2n(Cl,O)2 superconducting homologous series have been briefly introduced. The emphasis is on the special charge reservoir block of the oxyhalide high Tc superconductror (HTSC), which consists of the halide layer instead of the routine oxide layer. Consequently the apical oxygen related to the p-type HTSC is missed in the compound whereas the apical chlorine bridges the conducting layer and the charge reservoir. In the context a novel hole doping mechanism named apical oxygen doping was introduced through partially substituting oxygen for chlorine. This chemical doping leads to an 80 K superconducting transition in the high pressure synthesized double layered (Sr,Ca)3Cu2O4(Cl,O)2 oxyhalide. Not only the high Tc, the oxyhalide cuprate superconductor also demonstrates the comparable physical properties to those of the full oxide HTSC, indicating the promising prospects to develop new high Tc oxyhalide superconductors.

Differential Equations and Their Solutions for Hugoniot Relation of Porous Materials along the Isobaric Path

LIU Fu-Sheng, JING Fu-Qian

2004, 18(1): 10-16 . doi: 10.11858/gywlxb.2004.01.003

PDF (829)

Abstract:
Shock compression techniques can be applied to porous materials to reproduce thermodynamic states at high temperatures and high densities, and a lot of Hugoniot data were published in the past two decades. To investigate the intrinsic relationship between Hugoniot curves of dense metals and porous ones is of importance for development of more reasonable equation of state (EOS) models. In this paper, a set of differential equations, which relate the temperature and density of the shocked states along an isobaric path in p-V-T space to its initial densities of the porous material, is deduced from the traditional three-terms EOS and Grneisen EOS of solids. The differential formula of Wu-Jing EOS and the analytic expression of the Wu-Jing variable (Rp) are given. It is emphasized that Wu-Jing EOS is resulted not only from the contribution of crystal vibration as traditionally considered but also from most of the thermal electron effects. The new differential equations are applied to porous copper, and the effects of the thermal electrons to shock temperature, compression density, and value of Wu-Jing variable are discussed. It shows that the existence of the thermal electrons will reduce the increase rate of Rp with decrease of density.

The Effect of Water on the Synthesis of Cubic Boron Nitride Crystal in the System of Mg-hBN

ZHANG Tie-Chen, WANG Xian-Cheng, DU Yong-Hui, SU Zuo-Peng, ZOU Guang-Tian

2004, 18(1): 17-20 . doi: 10.11858/gywlxb.2004.01.004

PDF (765)

Abstract:
Synthesis of cubic boron nitride (cBN) crystal in the system of Mg-hBN with water, in the form of free or bonded, was investigated under the pressure and temperature of 4.5~5.5 GPa and 1 400~1 800 ℃. Results indicate that the form and the amount of water have important effect on the colour, the nucleation rate and the growth of cubic boron nitride crystals. Free water can depress the number of nucleus, and bonded water will change the colour and decrease the temperature for the synthesis of cBN crystals.

Experimental Investigation and DEM Simulation of Mass Mixing under Shock Loading

GONG Ping, TANG Zhi-Ping, SHEN Zhao-Wu

2004, 18(1): 21-26 . doi: 10.11858/gywlxb.2004.01.005

PDF (808)

Abstract:
Tin and lead beads are chosen to conduct the high velocity impact experiments with an explosive plane wave generator. The impact velocity is about 2 km/s. A metallurgic picture of the recovered specimen shows that there are four bands along the interfaces between tin and lead. The width across the bands is about 60~80 m. The SEM examination discloses that these bands are the mass mixing regions of tin and lead. The dynamic diffusion coefficient of the experiments is 0.9 cm2/s, which is much higher than that at quasi-static case. A discrete element simulation (DEM) demonstrates the process and mechanisms of the observed mass mixing for Pb-Sn beads under shock loading at meso-scale qualitatively.

The Extent and Crystal Structure of the Solid Solution Based on Ca2Pr2Cu5O10

SONG Gong-Bao, HAN Cang-Qiong, LIANG Jing-Kui, RAO Guang-Hui

2004, 18(1): 27-35 . doi: 10.11858/gywlxb.2004.01.006

PDF (785)

Abstract:
The extent and crystal structure of the solid solution based on Ca2Pr2Cu5O10 were studied by X-ray diffraction combined with Rietveld structure refinement. According to the principle of valence neutralization and the disappearing-phase method, in the Ca-rich region (i.e. Ca/Pr1) the composition of solid solution can be expressed as the general stoichiometry Ca2+xPr2-xCu5O10, and in the Pr-rich region (i.e. Ca/Pr1) as Ca1.7Pr2.2Cu5O10, Ca1.4Pr2.4Cu5O10, i. e., the solid solubility of the Ca2Pr2Cu5O10-based solid solution can be determined as from Ca2.4Pr1.6Cu5O10 to Ca1.4Pr2.4Cu5O10. The crystal structure of Ca2Pr2Cu5O10 based solid solution is an incommensurate phase based on the orthorhombic NaCuO2-type subcell. The lattice parameters of Ca2.4Pr1.6Cu5O10 subcell are a0=0.282 46(7) nm, b0=0.636 93(1) nm, c0=1.067 94(1) nm, and its orthorhombic superstructure is with a=5a0, b=b0, c=5c0. The Ca2.4Pr1.6Cu5O10 structure is also determined by using a monoclinic supercell with space group P21/c, Z=4, a=5a0, b=b0, c=c0/sin and =104.79or 136.60, V=5a0b0c0. In the structure of the solid solution based on Ca2Pr2Cu5O10, the mutual substitution between Pr and Ca is possible in some bound. Furthermore, they are distributed disorderly in the structure.

Effect of Preparation Pressure on Magnetoresistance of La2/3Sr1/3MnO3

TANG Yan-Kun, SUI Yu, QIAN Zheng-Nan, LIU Yu-Qiang, XU Da-Peng, SU Wen-Hui

2004, 18(1): 36-39 . doi: 10.11858/gywlxb.2004.01.007

PDF (826)

Abstract:
The effect of preparation pressure on the structural, magnetic and electronic properties has been investigated for nanostructured bulk samples of La2/3Sr1/3MnO3. The results show that the grain size decreases and magnetoresistance varies with preparation pressure growth. Low-field magnetoresistance weakens in the whole experimental temperature range when preparation pressure increases, which can mainly attribute to stronglink grain boundaries of samples under high preparation pressure. And highfield magnetoresistance gradually becomes stronger at T200 K, however becomes weaker at T200 K with the increase of preparation pressure, which can mainly due to the change of grain size caused by preparation pressure.

Two-Dimensional Simulation of Transient Detonation Process for H2-O2-N2 Mixture

DONG Gang, FAN Bao-Chun, XIE Bo

2004, 18(1): 40-46 . doi: 10.11858/gywlxb.2004.01.008

PDF (1036)

Abstract:
By solving the two-dimensional Euler equations coupled with the chemistry, a numerical simulation of transient detonation process induced by flame for H2-O2-N2 mixture was performed, and a detailed chemical mechanism for H2-O2-N2 system, which included 19 element reactions and 9 species, was involved. A splitting operator method was used to treat separately the hydrodynamical process and chemical process in the detonation simulation. The TVD scheme was used to capture the detonation wave and the Gear algorithm was used to solve the chemical reaction. The calculated results show that combustion rate of flame can be accelerated and lead to the occurrence of detonation when the initial mole fraction ratio of the mixture is H2∶O2∶N2=0.4∶0.4∶0.2 and the initial nondimensional temperature is T/T0=5.3, the detonation wave can be propagated steadily with the detonation velocity of 2 300 m/s. The reflection of the detonation wave can be observed. In addition, the variations of species concentrations and temperature behind the detonation wave were also discussed in order to understand the inherent structure behind the detonation wave.

Numerical Simulation of Debris Cloud Produced by Hypervelocity Impact of Projectile on Bumper

ZHANG Wei, PANG Bao-Jun, JIA Bin, QU Yan-Zhe

2004, 18(1): 47-52 . doi: 10.11858/gywlxb.2004.01.009

PDF (957)

Abstract:
All spacecraft in low orbit are subject to hypervelocity impacts by meteoroids and space debris. These impacts can damage spacecraft flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. In order to ensure the astronauts safety and spacecraft normal operation, the design of meteoroids and space debris protection configuration become an important problem of spacecraft design. The numerical simulations of debris cloud produced by projectile hypervelocity impact on bumper at normal and oblique angles have been carried out using the SPH (smoothed particle hydrodynamics) technique of AUTODYN hydro-codes in this paper. The results using two and three-dimensional simulations are given. The effect of bumper thickness, projectile shape, impact velocity and material models etc. on debris cloud has been investigated. The simulation results are compared with experimental results, and the simulated debris cloud shapes and debris cloud characteristic points velocity are consistent very well with experimental results.

Diffusion and Infiltration Mechanisms of Cobalt through Diamond Layer during the Sintering of Polycrystalline Diamond Compacts

DENG Fu-Ming, CHEN Qi-Wu

2004, 18(1): 53-58 . doi: 10.11858/gywlxb.2004.01.010

PDF (927)

Abstract:
The mechanisms of solid cobalt diffusion, molten cobalt infiltration and two wave-like cobalt peaks movement through diamond layer during the sintering process were discussed theoretically according to the experiment data. Results show that the solid cobalt diffusion coefficient under 5.8 GPa and at 1 300 ℃ is about 1.610-7 cm2/s, which is almost the mean value between the solid cobalt diffusion coefficient (310-10 cm2/s) at the same temperature under atmospheric pressure and the liquid cobalt diffusion coefficient (510-5 cm2/s) under 5.8 GPa and at 1 300 ℃. It also shows that the infiltration time of molten cobalt through diamond layer for diamond grain size 10 m and 1 m are about 0.5 s and 28 s respectively, and the moving velocity of the two wave-like cobalt peaks were about 50 m/s and 100 m/s, respectively.

Studies on the Equilibrium State of Mixture Following Shock Compression

LIN Hua-Ling, HUANG Feng-Lei, HU Yu-Xin, YU Wan-Rui, FANG Jian-Qing

2004, 18(1): 59-69 . doi: 10.11858/gywlxb.2004.01.011

PDF (741)

Abstract:
The mixture is as a randomly distributed component grains in three-dimensional meshes. The shock compression behavior of mixtures is simulated numerically by using the 3D thermodynamics finite element method. We have studied the course of tendency to the thermodynamic equilibrium, the characteristic time of temperature equilibrium, the characteristic time of pressure equilibrium and the equilibrium state of mixture following the shock compression and found the relation between the characteristic time of temperature equilibrium and the square of the grain dimension of mixture and the linear relation between the characteristic time of pressure equilibrium and the grain dimension. The shock compression behaviors of some alloys are simulated numerically, and the results are compared with the fraction volume model of EOS, the superposition principle of the first shock Hugoniot, and the experimental results. Except for the shock temperature, the results are in good agreement with each other. The fraction volume model and the superposition principle cannot yield reasonable shock temperatures, but the numerical simulation method does.

Influence of Ultra High Pressure (UHP) on Micro-organisms in Watermelon Juice

ZENG Qing-Mei, PAN Jian, XIE Hui-Ming, YANG Yi, XU Hui-Qun

2004, 18(1): 70-74 . doi: 10.11858/gywlxb.2004.01.012

PDF (968)

Abstract:
The relation between the survivors of micro-organisms and the processing pressure and the pulse pressure processing was investigated in UHP treatment to watermelon juice. And species of baroduric bacteria were discriminated. Processing pressure is between the atmosphire pressure and 500 MPa, and the pressurized duration 10 min in this experiment. Results show that under the ambient temperature (30 ℃) and pressure equal to or above 400 MPa the number of natural microflora, yeast, mold and coliform bacteria meets the requirement of National Food Hygienic Standard of China. When the times of pulse pressure processing increases, the survivors of micro-organisms decreases. Gram positive bacteria are the main part, 70%, of the survived bacteria, and the rests are the Gram negative bacteria and molds.

Isothermal Equation of State of Aluminium

ZHANG Jian, XIE Yan-Wu, PAN Yue-Wu, JIAO Hu-Jun, DAI Quan-Qin, CUI Qi-Liang, LIU Jing, ZOU Guang-Tian

2004, 18(1): 75-77 . doi: 10.11858/gywlxb.2004.01.013

PDF (625)

Abstract:
We have studied the equation of state (EOS) of aluminium by using energy dispersive synchrotron radiation X-ray diffraction technique at room temperature under in situ pressures up to 21.5 GPa. The data were fitted to Murnaghan equation of state and gave the bulk modulus and its first order derivative of aluminum: B0=(772) GPa, B0= 4.80.3. We attributed the small deviation of our result from those in the literature to the nonhydrostatic effects caused by the pressure transmitting medium NaCl. Yet we have not found any convincing evidence for a phase transformation in the experimental pressure range.

Comment on the Pressure Gauge for the Experiments at High Temperature and High Pressure with DAC

ZHENG Hai-Fei, SUN Qiang, ZHAO Jin, DUAN Ti-Yu

2004, 18(1): 78-82 . doi: 10.11858/gywlxb.2004.01.014

PDF (1110)

Abstract:
As a pressure gauge, Ruby is the most common and wildly used mineral for determining pressure in DAC experiments, but it has difficulty in such an experiment that simultaneously contains high temperature and water. Quartz is a new mineral proposed recently as a pressure gauge and it can be used with the system containing water, however it is limited at the pressure p2.0 GPa and the temperature T600 ℃. On the other hand, equation of state (EOS) of material is much reliable for determining the pressure in the experimental studies with DAC, but it is inconvenient and limited by the condition of instrument. For example, EOS of water is useful if the system is aqueous solution and no mineral can be used as a pressure gauge in order to avoid any interaction. Therefore, comments and suggestions have been addressed in this manuscript.

Effects of W Diffusion Barrier Layer for Diamond Coatings Deposited on WC-Co Substrates

WANG Chuan-Xin, WANG Jian-Hua, MAN Wei-Dong, MA Zhi-Bin, WANG Sheng-Gao, KANG Zhi-Cheng

2004, 18(1): 83-89 . doi: 10.11858/gywlxb.2004.01.015

PDF (770)

Abstract:
Two different W interlay/substrate bonding interfaces for the adhesion of diamond film deposited on WC-Co substrate were investigated using bias enhancing nucleation method, in microwave plasma enhanced chemical vapor deposition (MWCVD) device. The results indicate that hydrogen plasma decarburization, W interlayer sputtering, recarburization with negative biasing induce chemical reaction bonding interface formed between the W interlayer and the substrate. Recarburized W interlayer in the initial diamond deposition strongly adhere to WC grains on the surface of WC-Co substrate, and consequently improved the adhesion of diamond film on WC-Co substrate. This pretreatment improved the adhesion of diamond film more obvious, compared with sputtering W interlayer directly on the substrate, in which physical bonding interlayer formed. Carburization with high negative biasing can improve the roughness of the substrate surface, and consequently improve the effect of mechanical interlock. The nucleation density was increased by negative biasing and therefore improved the contact area between the diamond film and the substrate, consequently improved the adhesion of diamond film on WC-Co substrate.

Research on Piezoresistance Sensitivity of Yb Film Sensor

TENG Lin, YANG Bang-Chao, DU Xiao-Song, ZHOU Hong-Ren, CUI Hong-Ling, XIAO Qing-Guo

2004, 18(1): 90-93 . doi: 10.11858/gywlxb.2004.01.016

PDF (954)

Abstract:
Yb film sensor was fabricated by vacuum evaporation technique, and its performance has been studied under the longitudinal quasi-static loading in the range of 1 GPa. The comparison of two group Yb film sensors, one is unheated treatment and the other is heat treatment at 300 ℃ for 1 h in vacuum, indicates that the piezoresistance coefficient of the heated film is larger than not only the unheated, but also the Yb foils. With the analyses of SEM and electric performance, it is discovered that heat treatment helps to grow crystal, decrease the film resistivity and improve the piezoresistance coefficient. XRD analysis reveals that pressure may promote the growth of Yb crystals. Also, after treatment by pressure (1 GPa) Yb film sensors are easy to fabricate and have stable performance, which may have extensive usage in industry.

Measurement of the Precursor Gas Accompanied with the Launch of Two-Stage Gas Gun

WANG Wei, WANG Xiang

2004, 18(1): 94-96 . doi: 10.11858/gywlxb.2004.01.017

PDF (925)

Abstract:
During the launch of hypervelocity projectile in the two-stage light gas gun, the remanent gas in target chamber and the pushing gas that leaks through the projectile might disturb the physical measurement of target sample. In this paper quartz gauges were used to detect whether the influence of such gases is in existence and how much it is. Our results show that the precursor gas exists indeed accompanied with the shoot of two-stage light gas gun, but its pressure is only about 10-2 GPa in amplitude and could not produce obvious influence to the usual high pressure experiments.

2004 Vol. 18, No. 1

Login in

NewsMore

LinksMore