高压物理学报

Studies of Raman Spectra for MnF2 at High-Pressures

ZHAO Yong-Nian, LIU Zhen-Xian, CUI Qi-Liang, XU Yi-Qiu, FAN Yu-Guo, ZOU Guang-Tian

1990, 4(1): 1-6 . doi: 10.11858/gywlxb.1990.01.001

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Abstract:
High-pressure Raman spectra of MnF2 are reported for the first time. The results show that MnF2 undergoes a structural transition at 1.32 GPa, though the octahedron consisting of 8-fluorine atoms in the cell does not disintegrate due to the transition. No Raman peaks can be seen in the spectrum taken at 3.21 GPa, demonstrating that MnF2 undergoes probably another structure phase transition.

A Material Test Technique for Super-High Pressure Gasket Material

ZHOU Kai-Yong, YU Xin-Lu

1990, 4(1): 7-16 . doi: 10.11858/gywlxb.1990.01.002

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Abstract:
The mechanical property of super-high pressure gasket material-pyrophyllite is studied in this paper. Based on the analysis of the press shear and the disc-squeezing methods, a new material test technique-pure internal slipping method is suggested. The principal advantage of this method is that the friction between the sample and dies has no influence on test results, so that the test results are perfectly determined by the plastic property of samples. According to this idea, a simple device is set up and a series of tests on the mechanical property of pyrophylite are carried out. On the other hand, a program for stress distribution analysis in the plastic region of samples by slip-line theory is worked out. By using this program, the relation between the average pressure p, cohesion K internal friction angle and the diameter-thickness ratio d/h can be calculated, and the procedure for calculating the material parameter K, from the test results p-d/h is suggested. The test results show that the fired temperature and the moisture have strong influence on the mechanical property of samples and some rules exist between them.

Equation of State and Electronic Transfer for Al, Cu, Pb and Ta under Ultrahigh Pressures

JIN Qing-Hua, DING Da-Tong, WANG Ding-Sheng, LI Guang-Wei

1990, 4(1): 17-23 . doi: 10.11858/gywlxb.1990.01.003

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Abstract:
The electronic structures of the elemental metal Al, Cu, Pb and Ta have been studied in terms of the Augmented Spherical Wave method. The equation of states (T=0) of the metals from the first principle calculations are in good accord with the experiments. The pressure-induced transferences of electrons between s, p and d orbital are discussed quantitatively within the compression range of V0/V=1.0~5.0. In transition metal (Ta) the transference is much pronounced because the s and p bands shift with respect to d band, while other three metals show fairly small transference because only the degree of hybridization changes for those states near Fermi level.

Equation of State of Rarefactional Region at T=0 K

LI Mao-Sheng, ZHANG Chun-Bin

1990, 4(1): 24-28 . doi: 10.11858/gywlxb.1990.01.004

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Abstract:
We studied the equation of state at temperature T=0 K and density 0. A new potential form for the cold pressure is presented. The only parameter in the cold pressure formula can be determined via sound velocity c0. The cold pressures obtained from this cold pressure formula are in accordance satisfactorily with those deduced semi empirically normal conditions, from fracture and normal pressure melting point, as well as from critical point.

Vibrational Spectra Studies on Hexagonal BN Crystal and the Synthesis of Cubic BN

QIU Shu-Zhen, LI Bo-Xun, ZHANG Xing-Dong

1990, 4(1): 29-35 . doi: 10.11858/gywlxb.1990.01.005

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Abstract:
X-ray diffraction analysis is used as a reference, the infrared absorption and Raman scattering spectra of various hBN, whose real structures vary from high three-dimensional order to turbostratic structure, are measured. The results indicate that with the lowering of the crystallinity, the position of its low frequency absorption that with the lowering of the crystallinity, the position of its low frequency absorption band and FWHM of Raman spectrum lines in fundamental vibrational spectra change characteristically, and exhibit distinctive minimum peaks respective. cBN synthesis tests are carried out with these hBN as starting materials. The results show that a certain crystallinity of hBN is necessary to the formation of cBN at high pressure and temperature in the presence of metal catalyst. The dependence of cBN synthesis results upon the hBN crystallinity, which is not a simple monotonic relation. The experimental results mentioned above are analyzed and discussed.

The Effect of Diamond Films Grown from Gas Phase on Properties of Substrate Diamond

ZHANG Tie-Chen, JIN Zeng-Sun, Lü Xian-Yi, GUO Wei-Li, ZOU Guang-Tian

1990, 4(1): 36-41 . doi: 10.11858/gywlxb.1990.01.006

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Abstract:
In the present paper, the high pressure diamond crystalline grain with perfect morphology, smooth crystal faces and 252~315 m size are used as substrates. Diamonds have been formed on the substrate diamond by thermal CVD method from gases mixture of methane and hydrogen. The results show that the thermal property of the substrate diamond would be improved evidently after diamond films were deposited on the substrate.

Optical Spectroscopic Experiments under Quasi-hydrostatic Pressure of 126.5 GPa

ZHA Chang-Sheng, ZHAO Shu-Hui

1990, 4(1): 42-49 . doi: 10.11858/gywlxb.1990.01.007

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Abstract:
A multifunctional spectroscopic system for high pressure experiments using diamond anvil cell has been established. It was used for optical absorption, reflectance, luminescence, and Raman scattering experiments, and a highest quasi-hydrostatic pressure of 126.5 GPa has been obtained for absorption experiment of ordinary liquid nitrogen. Authors represent a fact that gasketed diamond anvil cell with beveled anvils and gas pressure medium shows a pressure generating capability much higher than 126.5 GPa, and the challenging problem is inefficient ruby fluorescence method of pressure measurement under high pressure.

A Study on the Formation and Stability of Quasicrystal Al4Mn under High Static Pressure

YAO Bin, ZHANG Qiang, SU Wen-Hui, XU Da-Peng

1990, 4(1): 50-56 . doi: 10.11858/gywlxb.1990.01.008

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Abstract:
The condition of the formation of quasicrystal Al4Mn and Al6Cr under high static pressure has been investigated for the first time. I-phase and T-phase have been observed in electron diffraction experiment. The structures of Al4Mn quenched at about 100 K/s are different under various pressures form 0.95 to 4.45 GPa. The phase transition from I-phase and T-phase to crystalphase has also been investigated. The results were discussed by noncrystalline dynamic theory.

Solid State Amorphous Reaction under High Pressure

YAN Zhi-Hua, CHEN Hong, HUANG Xin-Ming, WANG Wen-Kui, LI Jin-Feng, WANG Yu-Ming

1990, 4(1): 57-62 . doi: 10.11858/gywlxb.1990.01.009

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Abstract:
The X-ray diffraction of the Ni50Ti50 multilayer samples annealed at low temperature and under various pressures is reported in this paper, in which the effect of pressure on the solid state amorphous reaction is considered for the first time. Based on the effects of pressure on the reaction thermodynamics and kinetics, the authors suggest that the failure of the reaction under the pressure above 2 GPa could be attributed to the high pressure suppression of the fast atomic diffusion. It is also proposed that the suppressed diffusion in the amorphization of the Ni-Ti series solid state reaction could be described by the B type kinetical model for thin film diffusion.

Measurement and Analysis of Strain and Calibration of Pressure in Piston-Cylinder Type Apparatus with 4.5 GPa Hydrostatic Pressure

SU Fang, CHE Rong-Zheng, XU Wei, YAN Fei-Na

1990, 4(1): 63-71 . doi: 10.11858/gywlxb.1990.01.010

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Abstract:
This paper gives an experimental method which improves the hydrostatic pressure in the present piston-cylinder type apparatus. Manganin gauges were made successfully and calibrated accurately by phase change of Bi. Measurement and analysis of both strain and relative displacement all show that (1) there are no synchronous contracting role of hoops in the range of 0.000 1~3.08 GPa when the pressure cavity is empty or full of liquid; (2) large difference between upper and lower oil pressure will bring about danger of high pressure explosion. In order to obtain the hydrostatic pressure higher than 3.08 GPa. We suggest to modify the criginal design: (1) if the internal hoop and the middle hoop combined into one and the outer hoop divided into an upper half layer and a lower half layer, strain of hoops will be enhanced; (2) adjusting the area of contact surface between hoops will help the synchronous contracting role; (3) increasing the unsupported area of sealed sleeve will reduce the difference between upper and lower oil pressure, hence will be advantageous to safety of operation.

The Electrical Resistivity of the Main Minerals in Ultramafic Rock, Eclogite and Gabbro under High Pressures

XU Huai-Ji, GUO Jin-Di

1990, 4(1): 72-77 . doi: 10.11858/gywlxb.1990.01.011

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Abstract:
Clinopyroxene, Labrador, omphacite, garnet and enstatite as the main minerals in ultramafic rock, eclogite and gabbro are selected as the samples to study the variations of resistivity of the mantl materials with pressures between 3 GPa and 20 GPa using a DAC device. The results indicated that the resistivities of these minerals increase obviously with pressures between 3 and 8 GPa, the effect of the pressure is reduced, and the resistivities of pyroxenes decrease with the pressure in variety of degrees. In the range of 14 to 20 GPa, the resistivity of enstatite increases obviously again with pressure, but the other minerals do not increase so clearly. In the mantle, in the depth of about 400 km, sudden increase of the conductivity was presented (McDonald, 1975), and the negative correlation between the resistivity of pyroxene and the pressure occurs just under this pressure (about 12 GPa). Is that a coincidence? It is a problem we shall study later.

Equations of State of Several Kinds of Alloy Steel at High Pressure

BAO Zhong-Xing, ZHANG Zhi-Ting

1990, 4(1): 78-80 . doi: 10.11858/gywlxb.1990.01.012

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Abstract:
The p-V relationships for alloy steel 45CrNiMoV, GCr15 and W18Cr4V at room temperature and up to 4.5 GPa are measured. Their Bridgman's equations, Grneisen parameter 0, bulk moduli B0 and first order pressure derivatives B0' of B0 are also given.

1990 Vol. 4, No. 1

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