高压物理学报

The Effect of Pressure Transmitting Medium on the High Pressure Experiments in Diamond Anvil Cell (DAC): Experimental Measurement of the Equation of State (EOS) of Pyrope

XU Ji-An

1987, 1(2): 97-101 . doi: 10.11858/gywlxb.1987.02.001

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Abstract:
The EOS data of pyrope in high pressure region measured in DAC technique by using Ar as pressure transmitting medium has been found to be different from that obtained by using methyl and ethyl alcohol mixture as pressure transmitting medium. It follows that in case of measuring the EOS data of materials with high value of modulus of elasticity, methyl and ethyl alcohol mixture cann't be used effectively as the transmitting medium in pressure region of exceeding 20 GPa. The utility of Ar high pressure scale hase been discussed.

Lattice Parameters of the Perovskite in Aluminum-Bearing Silicates

WENG Ke-Nan

1987, 1(2): 102-109 . doi: 10.11858/gywlxb.1987.02.002

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Abstract:
In the present paper, the sysem FeO-MgO-Al2O3-CaO-SiO2 has been studied in an attempt to determine the effects of aluminum and calcium on the stability of the silicate perovskite. A series of synthesized silicate glasses were converted to silicate-perovskites in a diamond cell at approximately 40 GPa and 1 500 ℃. Powder X-ray diffraction analyses of these quenched samples showed that at least 25 mol% Al2O3 was dissolved in perovskite forming (Mg,Al)(Si,Al)O3. The increase in volume of the perovskite phase was regarded as a function of increasing Al2O3 content. The addition of Al2O3 caused a significant increase in the molar volume of MgSiO3-Pv than FeSiO3. Because of the large volume diference between garnet and perovskite, there would be no stadility field for garnet in the lower mantle at depths greater than the 650 km seismic discontinuity. In th study of the compositions En80Wo18Co2 and En73Wo24Co3 at 40 GPa, the run products yielded X-ray diffraction patterns almost identical with those of calcium-free perovskites. The calcium would probably form a Ca-rich Al-bearing silicate perovskites at high pressure and high temperature, but it could not be quenched.

Gauge Field Theory of the Breaking Criterion of Materials Subjected to Intensive Shock Loading

WANG Ke-Gang, DONG Lian-Ke, LONG Qi-Wei

1987, 1(2): 110-120 . doi: 10.11858/gywlxb.1987.02.003

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Abstract:
The paper presents the generalized E. Noether symmetrical theorem providing the Bessel-Hagen's divergence on gauge field theory is invariance. With the aid of the theorem and gauge field theory of defects, the formula of a breaking criterion of materials subjected to loading is obtained. The formula quantitatively expresses the effect of defects and loading on damage of materials. As a special example. the paper also presents a concrete formula of the breaking criterion of materials under intensive shock loading, and the formula quantitatively expresses the effect of shock speed, pressure and defects on damage of materials.

Crystallization of Amorphous Fe78Si9B13 Alloy under High Pressure

WANG Zhao, MENG Zhao-Fu, WANG Yu-Ming, WANG Wen-Kui

1987, 1(2): 121-129 . doi: 10.11858/gywlxb.1987.02.004

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Abstract:
In this paper the effects of high pressure on the crystallization temperature of amorphous Fe78Si9B13 alloys were investigated. The time-temperature-transition (T-T-T) diagrams at atmosphere and 7.5 GPa were obtained. And it was found that both crystallization temperature and the phase formation were influenced by the pressure.

Superconductivity of Crystallized Phases from Amorphous La80Al20

HUANG Xin-Ming, HE Shou-An, WANG Wen-Kui

1987, 1(2): 130-137 . doi: 10.11858/gywlxb.1987.02.005

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Abstract:
In this paper, we studied the structures and superconductivity of the samples annealed from a morphous La80Al20 alloy under different treatments. It was found that when annealed in vacuum at 250 ℃, the a morphous alloy crystallized into the sample of a tetragonal single phase La4Al for which where is no TC as T4.2 K. When annealed in vacuum at 300 ℃, or 450 ℃, the amorphous samples crystallized into the samples of hexagonal La3Al, -La, -La and some unknown phases, the TC ofthese multiphase samples is lower than 6.0 K. When annealed under 6 GPa, if annealing temperature Ta300 ℃, the amorphous alloy crystallized into the sample of hexagonal La4Al, the parameters of which are exactly the same as hexagonal La3Al and TC of which is lower than 5.7 K; if Ta350 ℃, the amorphous alloy crystallized into the sample of hexagonal La3Al and a unknown phase H, the TC of new phase H is 6.3 K.

Transport Properties of Electrons in Metallic Glasses Fe100-xBx under Hydrostatic Pressure

HAN Shun-Hui, HAN Han

1987, 1(2): 138-143 . doi: 10.11858/gywlxb.1987.02.006

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Abstract:
The temperature dependece of electric resistance in metallic glasses Fe100-xBx (16x22) under pressure of 0~1.2 GPa and temperature of 54~300 K was measured. The experimental data are fitted and discussed with the generalized Ziman theory herein.

Badiometric Measurements of Overtaking Rarefaction Wave Velocities in Shock-Loaded Brass under High Pressures

WANG Gui-Chao, XIE Pan-Hai, TAN Zhen-Nan

1987, 1(2): 144-149 . doi: 10.11858/gywlxb.1987.02.007

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Abstract:
Overtaking rarefaction velocities in shock-loaded H62-brass were measured by using radiometry in the pressure range from 143~182 GPa, and the PMMA were used as the window material. Formulae for determing the overtaking rarefaction velocity are given in case of a symmetrical impaction. The experimenal results showed that the shock melting in H62-brass are occured in the region between 143 and 162 GPa.

EOS and Phase Structure Stability of Lithium

ZHANG Chun-Bin, ZHANG Shi-Ze, LI Shao-Meng, LIN Shao-Ming, ZHANG Wan-Xiang

1987, 1(2): 150-154 . doi: 10.11858/gywlxb.1987.02.008

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Abstract:
Using the LMTO method, we calculated the EOS for bcc and fcc lithium with compressibility ranging from 1 to 12. The results (: 1~12, pressure up to 103 GPa) are compared with the experiments (3) and the TF model. The phase structure stability was studied by calculating the total energy. It is shown that the fcc structure is stabler than the bcc one.

Calculation of the Gruneisen Parameter and Its Pressure Dependence for NaCl

WU Shao-Zeng, ZHANG Cheng-Xiang, WU Li-Xin

1987, 1(2): 155-164 . doi: 10.11858/gywlxb.1987.02.009

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Abstract:
The Gruneisen parameter and its pressure dependence for NaCl are calculated by using the rigid-ion model. In the calculation a new form of potential energy, which has been used previously to successfully calculate the equation of state of NaCl, is adopted as follows. Two forms of modified Born-Mayer potential are used as the functional forms of the repulsive energy between the nearest neighbor ions and the correlation energy are also taken into account by using the data from the electronic gas model. The agreement of our results with the experimental data is satisfactory.

The Thermal Stability and Variation of Precipitated Phase in Amorphous Zr70Cu30 Alloy at High Pressure

SHEN Zhong-Yi, CHEN Gui-Yu, ZHANG Yun, YIN Xiu-Jun, SHEN De-Jiu, WU Hao-Quan

1987, 1(2): 165-172 . doi: 10.11858/gywlxb.1987.02.010

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Abstract:
The thermal stability and the variation of constituent crystallised phase in annealing a morphous Zr70Cu30 alloy under a pressure of 2 GPa were examined by resistance measurement and X-ray diffration analysis results show an increment of crystallizing temperature at high pressure. An evident variation on phase equilibrium was observed. Instead of the precipitation of CuZr2 compound (with a little amount of -Zr) at normal pressure, a mixture of Cu10Zr7 compound and -Zr occurs under 2 GPa.

Preparations of Large-Scale YBaCuO System Sample and Its Superconductivity

HAI Yu-Ying, ZHANG Wan-Xiang

1987, 1(2): 173-175 . doi: 10.11858/gywlxb.1987.02.011

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Abstract:
Using the hydrostatic pressure method we have prepared some uniform superconducting YBaCuO bars with regular shape of 11 mm diameter and 110 mm length. The samples show onset of superconductivity at 105~106 K. Zero resistance in the range from 89 K to 92 K, and resistive transition width 5~8 K.

The Pressure Gradient in the Superhigh Pressure Chamber for Diamond Synthesis

YANG Zong-Qing, WU Zhao-Qing, WANG Wei-Dong, ZHANG You-Jun, LI Jia

1987, 1(2): 176-183 . doi: 10.11858/gywlxb.1987.02.012

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Abstract:
The pressure gradient has been measured by authors using graphite which is widely applied to diamond synthesis instead of traditional material silver chloride. The pressure gradient in graphite pressure chamber increases with the pressure. The axial pressure gradient is 21.8 MPa/mm and the radial one is 18.8 MPa/mm when the chamber center is at the pressure of 5.5 GPa. It has been also found the pressure gradients in the axial direction and radial direction are almost same at low pressure, but the difference becomes remarkable with increasing pressure. On the other hand, the pressure gradient in silver chloride chamber decreases with the increasing pressure. Some investigations were carried out on the relative pressure gradient, and we found it decreases as the pressure increases. When center pressure is 5.5 GPa, the axial relative pressure gradient is 0.003 96 mm-1 and the radial is 0.003 48 mm-1 . It is suggested that the temperature field could be reasonably designed by taking account of relative pressure gradient.

A Study on the Oxidation Resistance of Sintered Diamond Polycrystals

WANG De-Xin, XUE Yong-Jin, JIAO Qing-Yu, LIU Pei-Luan

1987, 1(2): 184-187 . doi: 10.11858/gywlxb.1987.02.013

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Abstract:
The oxidizing temperature of sintered diamond polycrystals was measured with the comprehensive differential heating analyser. It has been concluded that the oxidation resistance of sintered diamond polycrystals is determined by those of the binders and the intermediate agglutinated layer between diamond grains.

Equations of State for Two Kinds of Stainless Steel at High Pressure

BAO Zhong-Xing, GU Hui-Cheng, ZHANG Zhi-Ting

1987, 1(2): 188-190 . doi: 10.11858/gywlxb.1987.02.014

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Abstract:
The p-V relationships for two kinds of stainless steel at room temperature and up to 4.5 GPa are measured and their Bridgman equations are given respectively. Using the coefficients a and b in these Bridgman equations, their Gruneisen parameter 0, bulk moduli B0 and first order pressure derivatives B0' of B0 are also calculated.

1987 Vol. 1, No. 2

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