高压物理学报

The Pressure-Temperature Relation for High-Pressure Gases with Compressibility Factor e-1Z at Constant Volume

CAO Zhi-Jue

1995, 9(3): 161-166 . doi: 10.11858/gywlxb.1995.03.001

PDF (819)

Abstract:
The pressure-temperature relation is analytically derived for high-Pressure mixed gases with compressibility factor e-1Z at constant volume in the vicinity of any temperature by using the basic formulae of canonical ensemble as well as thermodynamic equation of state. Applying these expressions to engineering thermophysics can reduce the times of tests, and to oil-chemical industry can estimate the effect of surrounding temperature on the pressurized tank. The calculated results are in accord with the experimental ones.

The Structure Transformation in the -FeOOH Nanometer Solid under High Pressure

SUI Yu, XU Da-Peng, SU Wen-Hui

1995, 9(3): 167-175 . doi: 10.11858/gywlxb.1995.03.002

PDF (715)

Abstract:
It is well known that the research on nanometer solid has brought to people's great interest in recent years, but only a few works has been done so far about the properties of nanocrystalline under high pressure. In the present paper, we have synthesized a series of -FeOOH nanometer solid by treating the ultrafine powder under the pressure range of 0.0～4.5 GPa and the temperature range of 200～350 ℃. The ultrafine powder was synthesized by using chemical hydrolysis method and its average diameter is 12 nm. Using X-ray diffraction (XRD) and differential thermal analysis (TG-DTA), we investigated the structural transformation of these nanometer solids. The results of XRD and TG-DTA experiments show that under cold pressure of 0.0～4.5 GPa, the structure of the nanometer solids do not change considerably, but on the other hand, the temperature of the heat-induced phase transformation (from -FeOOH phase to -Fe2O3 phase) in these -FeOOH nanometer solids is raised obviously with increasing pressure, from 203.8 ℃ at normal pressure to 274 ℃ at 4.5 GPa. This variation can be interpreted by the effect of pressure on the coordinate state of the OH- group in the interface of nanometer solid. After treating under hot pressure, both the formation and temperature of the structural transformation of -FeOOH nanometer solid are very different from the results under cold pressure. Under the hot pressure of 4.5 GPa, the temperature of the structural transformation from -FeOOH phase to -Fe2O3 phase is far above 350 ℃. However under the condition of 3.0 GPa, 200 ℃ and 4.5 GPa, 350 ℃, we firstly observe the structural transformation, from -FeOOH phase to -FeOOH phase. It is more interesting that we obtain a new metastable phase of FeOOH in the above structural transformation at the condition of 4.5 GPa and 200 ℃. These special variation can be interpreted by considering the effect of pressure combining temperature on the OH- group in the nanometer solid at the same time.

Behavior of Li8SiN4 on cBN Synthesis

ZHOU Yan-Ping, YAN Xue-Wei, ZHAO Ting-He, MA Xian-Feng

1995, 9(3): 176-182 . doi: 10.11858/gywlxb.1995.03.003

PDF (717)

Abstract:
Ternary nitride Li8SiN4 is prepared at 700～750 ℃ in N2 by solid state reaction with LiH and Si3N4. Effects of reaction temperature, time and circumstance as well as stability on pure phase Li8SiN4 are studied in detail. Cubic BN is synthesized using Li-complex nitride and additive Li8SiN4 as catalyst-solvent in order to examine the behavior of silicon. The morphology and surface structure of cBN crystals are observed by SEM. Most of cBN crystals show off truncated octahedral shapes, and crystal surfaces are smooth and dense. The results suggest that Li8SiN4 involves in the reaction for hBN to cBN and is in the form of SiO2 deposited on its surface.

Effect of High Pressure on the Conductivity of Polyaniline

LIU Zhen-Xing, ZHANG Dian-Lin, WAN Mei-Xiang, LI Ming, LI Jun-Chao

1995, 9(3): 183-187 . doi: 10.11858/gywlxb.1995.03.004

PDF (642)

Abstract:
For conducting polymer polyaniline (PANI) the degree of ordering, conductivity and hopping barrier changes greatly after oriented stretching. In this paper we have studied the effect of hydrcotatic high pressure on the electrical property of oriented and unoriented PANI films. We find that for unoriented PANI film, the conductivity is monotonously increased and hopping barrier T0 is monotonously decreased with the increase of pressure, on the other hand for oriented PANI film the conductivity shows a maximum at 0.47 GPa and T0 shows a minimum between 0.35~0.71 GPa. This anomalous behaviour is different from other conducting polymers, such as polyacetylene, polythiophine, etc.

Repulsive Potential and Their Multi-Body Expansion of Compressed Atomic Cluster Hen (n＝3, 4, 5)

LIU Fu-Sheng, GOU Qing-Quan, JING Fu-Qian

1995, 9(3): 188-194 . doi: 10.11858/gywlxb.1995.03.005

PDF (704)

Abstract:
Lowdin scheme is applied to calculate the repulsive potentials and their multi-body expansion of compressed atomic clusters Hen (n＝3, 4, 5). It is found that the multi-body expansion converges more slowly as the members of atoms and compression increase. In multi-body expansion, the two-body and four-body contributions are repulsive and the three-body and five-body contributions are attractive. Therefore, when we treat many-body interaction by means of multibody expansion approach, the two-body approximation always overestimates repulsive potentials and three-body corrections soften system too much. These results agree with the new experiments. It is also found that the four-body and five-body contributions are important for the equation of state of dense helium.

Compressive Property and Equation of State of 4.2Ni2.45Fe0.35CoW Alloy under Pressure from 100 GPa to 500 GPa

WANG Jin-Gui, SHI Wei-Feng

1995, 9(3): 195-202 . doi: 10.11858/gywlxb.1995.03.006

PDF (692)

Abstract:
Investigation of compressive property for tungsten alloy 4.2Ni2.45Fe0.35CoW (93W) in the pressure ranging from 100 GPa to 500 GPa was performed by using a two-stage light-gas gun and symmetric impact technique, The relation between shock velocity, D, and particle velocity, u, can be expressed by D=4.008+1.277u (km/s), which is in good agreement with the Hugoniot prediction by a different method of Hugoniot for mixture materials.

Theoretical Study on Equation of State of Water at High Temperature and High Densities

LIU Fu-Sheng, GOU Qing-Quan, JING Fu-Qian

1995, 9(3): 203-207 . doi: 10.11858/gywlxb.1995.03.007

PDF (768)

Abstract:
MCR theory is applied to calculate the pVT equation of state of H2O molecules system by using a potential function of two molecules with exp-6 type formula. Comparisons with MD simulations show that states of the system may be at solid phase space in such high temperatures of 2 000～4 000 K because of strong attraction between molecules. In this phase area, its thermodynamic properties can not be treated by MCR theory. However, MCR accurately predicts the pVT equation of state of H2O molecules system in higher temperature liquid phase space.

Equations of State and Phase Transitions in KH2PO4 and (CH3NHCH2COOH)CaCl2 at High Pressure

BAO Zhong-Xing, Schmidt V H, LIU Cui-Xia, YU Ting-Nan

1995, 9(3): 208-212 . doi: 10.11858/gywlxb.1995.03.008

PDF (709)

Abstract:
The p-V relationships for KH2PO4 (KDP) and (CH3NHCH2COOH)CaCl2 [trissarcosine calcium chloride (TSCC)] at room temperature and up to 4.5 GPa have been studied using the piston-cylinder type measurement device. The experimental results show that the phase transition in KDP occurs near 2.1 GPa and TSCC undergoes two phase transitions near 0.8 GPa and 3.2 GPa. Their equations of state before and after phase transition, Grneisen parameters 0, bulk moduli B0 and first order pressure derivatives, B0' of B0 are also given.

Transformation of Boron Oxide B2O3 under High Pressure and High Temperature

LIU Xiao-Yang, ZHAO Xu-Dong, HOU Wei-Min, SU Wen-Hui

1995, 9(3): 213-217 . doi: 10.11858/gywlxb.1995.03.009

PDF (847)

Abstract:
This paper describes the transformations of boron oxide B2O3 under high pressure and high temperature. We have found that boron oxide B2O3 with cubic system is transformed into hexagonal and orthorhombic B2O3 under a pressure of 5.0 GPa and a temperature of 800 ℃. Under pressure of 4.0 GPa and temperature of 1000 ℃, cubic B2O3 is transformed into amorphous state, whose colour is white. Moreover, structural changes with increasing temperature and pressure, and method of quenching from a fusing state under high static pressure are discussed.

Investigation of the Resistivity in the Reaction Cell While Synthesizing Diamond under HPHT

LUO Xiang-Jie, DING Li-Ye, CHEN Jiang-Hua, HONG Shi-Ming, ZHOU Ming-Hua, LUO Jun-Yi, LIU Xian-Yong

1995, 9(3): 218-223 . doi: 10.11858/gywlxb.1995.03.010

PDF (736)

Abstract:
By measuring the resistance of the reaction cell continuously, the progress of diamond synthesis under various HPHT was detected. The resistivity may vary with the ever changing phase of the materials in the cell and be closely connected to the nucleation and growth of diamond. Such a innovated technique is highly valued for the possibility to know what is happening in the enclosed HPHT reaction cell while the process of synthesis is progressing.

Effect of Hydrostatic Pressure on Growth and Breeding of Bacteria in Raw Milk

CHI Yuan-Bin, MA Xiao-Fan, CUI Tian, CUI Qi-Liang, JIN Zeng-Sun

1995, 9(3): 224-227 . doi: 10.11858/gywlxb.1995.03.011

PDF (803)

Abstract:
The effect of pressure on growth and reproductive capacity of bacteria in raw fresh milk is studied in range of hydrostatic pressure from 20 to 120 MPa. The result is following: At room temperature and 20 MPa the raw fresh milk was pressed for 5 minutes then it was return to normal pressure, the physiologic activity of bacteria in the raw fresh milk have a striking reduction, this effect is the pressure effect in no situ. The effect of pressure up to 120 MPa has not obvious difference from that of 20 MPa.

Experimental Investigation of Ignition Features for Solid Explosive Charges under Pressure-Shear Loading

LU Fang-Yun, XUE Hong-Lu, CHEN Pei-Qi, WEI Yu-Zhang, ZHANG Zhen-Yu

1995, 9(3): 228-233 . doi: 10.11858/gywlxb.1995.03.012

PDF (635)

Abstract:
In this paper, one-dimensional planar pressure-shear loading upon solid explosive charges (T/Г40/60, 10#-159), which were cohered to the rear surface of the quartz piece, were realized by means of the waves propagation resulting from planar impacting on a Y-cut quartz piece. Longitudinal (or normal) and transverse (or shear) movement histories in the explosive samples were recorded by means of electric-magnetic particles velocity (EMPV) gages. They are Lagrangian gages embedded in the sample. By analysis of the law of pressure shear wave propagation in the sample, which would result in the realization of ignition features of solid explosives under pressure-shear loading.

Equation of State for Alkali Halide Crystals High Pressure

YAN Zu-Tong

1995, 9(3): 234-240 . doi: 10.11858/gywlxb.1995.03.013

PDF (639)

Abstract:
In this paper, starting from the total interaction potential function among ions, the equation of state and the relations between B0 and B0', B0 are derived for alkali halide crystals. The calculated value is in good accord with the experimental value. The results show that the equation of state is suitable to describe the isothermal compressing behaviour of alkali halide crystals at room temperature and high pressure in the state without pressure-induced transitions.

1995 Vol. 9, No. 3

Login in

NewsMore

LinksMore