高压物理学报

The Graphitic Recrystallization and Growth of Diamond under High Pressure and Temperature

HAO Zhao-Yin, HE Yi-Xing, CHEN Yu-Fei, WANG De-Rong, WANG Yan-Di

1992, 6(2): 81-91 . doi: 10.11858/gywlxb.1992.02.001

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Abstract:
In this paper, we have observed graphitic recrystallization with different shapes under high pressure and different high temperature. One revealed that the transformation from graphite into diamond is related to spherical graphitic recrystallization in the catalyst-solvent alloy. The different shapes and surface of diamond crystals have showed that diamond growth is a complex process. One also studied a graphitic recrystallization grains with shape of hexagon-octahedron which are a fundamentals transforming into diamond. In these studies, we have found that the method was used to grow a larger and regular diamond crystal.

The Phase Diagram of Solid Solution 60%NaAlSi2O6-40%CaMgSi2O6 at High Temperatures and High Pressures

ZHAO Ting-He, YAN Xue-Wei, CUI Shuo-Jing, LIU Li-Jun, ZHAO Wei

1992, 6(2): 92-98 . doi: 10.11858/gywlxb.1992.02.002

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Abstract:
The solid solution, 60%NaAlSi2O6-40%CaMgSi2O6 was studied under 1.0~5.0 GPa, 700~1 750 ℃ by using a cubic anvil press. A high-temperature and high-pressure phase diagram for this 60%NaAlSi2O6-40%CaMgSi2O6 solid solution was obtained. A translucent jewel (Jd0.6Di0.4) was obtained in our experiment, surface of which shines with a glorious green color. The unit cell parameters of synthetic Jd0.6Di0.4: a=0.953 9 nm, b=0.857 8 nm, c=0.523 3 nm, =107.28, and V=0.417 02 nm3.

Ultrasonic Phase Comparison Technique and Its Application in Elastic Properties Research in the Solid

WANG Ru-Ju, WANG Ji-Fang

1992, 6(2): 99-107 . doi: 10.11858/gywlxb.1992.02.003

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Abstract:
A ultrasonic interferometric techniquephase comparison method is introduced. As applications, the ultrasonic velocities propagating in semiconductor GaAs, composites with Si3N4 whiskers, transition metal oxide CoO and high Tc superconductor AgYBa2Cu3O7- were measured. For the sample CoO and AgYBa2Cu3O7- the dependence of ultrasonic velocities on both pressure and temperature also were measured. Using pulse echo overlap method, it is difficult to perform the above measurement. The phase comparison method makes measuring easy and accurate. It offers a wide measuring frequency range, from several megahertz to tens megahertz. The method can be used to measure ultrasonic velocities in thin samples (1~2 mm) and in the samples that have serious ultrasonic attenuation. It is expected to obtain wide application in elastic properties research in the solid.

Dynamic Properties of LY-12 Aluminum AlloyIts Punching Shear Fracture Strength at High Temperatures

WANG Chun-Kui, LIU Xiao-Ping, ZHENG Rong

1992, 6(2): 108-115 . doi: 10.11858/gywlxb.1992.02.004

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Abstract:
This paper describes the measurements of the punching shear fracture strength of LY-12 aluminum alloy from room temperature to 400 ℃, and the static shear strength in the same temperature range. The ratio of the dynamic punching shear to the static is about 1.3∶1 at room temperature to 4∶1 at 400 ℃. It shows that the high temperature dynamic strength is considerably higher than that of static.

The Solitonic Excitation and the Fractal Properties in Bio-Macromolecular System

PANG Xiao-Feng

1992, 6(2): 116-126 . doi: 10.11858/gywlxb.1992.02.005

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Abstract:
Properties of the solitonic excitations generated by the localized fluctuation and the structure deformation due to ATP hydrolysis and other excitation in DNA were discussed by using a new Hamiltonian function. A solitonic motion model in DNA was established. Some elementary biological functions such as the duplication, the transcription and the inheritance of DNA, as well as its fractal feature could be elucidated with this new solitonic model.

Experimental Study on the Polycrystal Diamond Synthesis from Graphite by Multiple Shock-Compressions

CHEN De-Yuan, JIN Xiao-Gang, YANG Mu-Song

1992, 6(2): 127-135 . doi: 10.11858/gywlxb.1992.02.006

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Abstract:
Pure graphite powders were subjected to single to fourfold shock-compressions by use of an explosively driven metal flyer impacting onto the recovery capsule, and polycrystal cubic diamond of high purity and with regular morphology was synthesized from the graphite under pressures from 24 to 37 GPa. Conversion ratio from graphite and particle size of diamond displayed an increased trend with the compression times. When the particle size of diamond is greater than about 100 m, however, it is easily to be fractured if the shock pressure is high (over 20 GPa) while the temperature is low (below 1 000 K).

Quasi-Static Compaction Studies of Propellant Beds

YANG Tao, JIN ZHi-Ming, LI Bao-Ming

1992, 6(2): 136-142 . doi: 10.11858/gywlxb.1992.02.007

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Abstract:
In this paper, quasi-static compaction experiments of propellant beds with different initial temperatures and particle sizes were performed. Stress-strain relations of the propellant beds during the compaction were measured. The relationship between the intragranular stress and the initial temperature were obtained. Combustion experiments in the closed bomb were conducted by using the standard propellant and the propellant after being compacted. The results show that the surface densification and damage of the propellant are the main factors that influence the combustion characteristics of the propellants.

The Determination of High Pressure Phase Diagrams of the Cd-Sn(0.2)-Zn Ternary Alloy

SONG Li-Zhu, YANG Hua, ZHAO Mu-Yu, SHEN Zhong-Yi, LIU Yong

1992, 6(2): 143-149 . doi: 10.11858/gywlxb.1992.02.008

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Abstract:
In order to verify the calculated results of the high pressure phase diagram of the ternary alloy system, several vertical sections of phase diagrams of Cd-Sn-Zn system with a constant composition of xSn=0.2 were determined by the method of differential thermal analysis (DTA) of 0, 0.5, 1.0 and 1.5 GPa. The liquidus determined at ordinary pressure coincides well with Bray's result. The eutectic temperature of the system increased by about 35 K from the ordinary pressure to 1.5 GPa. And the eutectoid composition changed about 0.08 mole fraction towards the zinc-rich side.

The Effect of Pressures on the Electrical Resistance of Amorphous Carbon

BAO Zhong-Xing, ZHANG Zhi-Ting, LIU Shi-Chao, YU Li-Zhi, CAO Chuan-Hua

1992, 6(2): 150-153 . doi: 10.11858/gywlxb.1992.02.009

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Abstract:
The influence of pressures on the electrical resistance of amorphous carbon is reported in this paper. The experimental results indicate that its electrical resistance decreases rapidly with the pressure in the low pressure range. To compare this behavior with that of graphite, the influence of pressure on the electrical resistance of graphite has also been studied.

Vibrational and Reflectional Spectra of cBN

LIU Li-Jun, YAN Xue-Wei, CUI Shuo-Jing, NIU Wei, ZHAO Ting-He, XIE Yun-Fen, ZHU Yi-Bing, SHI Chang-Huai

1992, 6(2): 154-160 . doi: 10.11858/gywlxb.1992.02.010

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Abstract:
Spectra of synthesized cBN crystal (black, yellow, brown in color and 50 m) were measured by using IR, Raman and UV. The results are described in the following sections: (1) According to the infrared absorption spectrum, the sharp 1 818 cm-1 and 1 548 cm-1 absorption spectrum bands is intrinsic vibration of cBN, while the defect absorption appears at 800 cm-1, 1 560 cm-1~1 740 cm-1 and 2 400 cm-1. (2) The Raman scattering spectrum shows that two lines appeared at 1 052 cm-1 and 1 034 cm-1 are in agreement with the fact the cBN possesses cubic symmetry without inversion center. The lines in the spectrum correspond to the Stokes components of first modes Raman scattering with the emission of transverse and longitudinal optical phonons in the center of the Brillouin zone. The presence of line 144 cm-1 can be accounted for by the emergence of local oscillation modes connected with the presence of impurity-defect complexes in the lattice. (3) The result of cBN reflection at spectrum indicates that three types of cBN crystals possess greater values of band gap which are Eg=6.12 eV (black), Eg=5.73 eV (yellow), Eg=5.71 eV (brown), respectively.

1992 Vol. 6, No. 2

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