高压物理学报

Ultrasonic Velocity and Attenuation Coefficient, Density and Adiabatic Compressibility of Petroleum Ether under High Hydrostatic Pressure

SU Fang, XIE Bin, WU Kun-Yu

1994, 8(2): 81-86 . doi: 10.11858/gywlxb.1994.02.001

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Abstract:
An apparatus for measuring ultrasonic velocity of liquid under different hydrostatic pressure was specially designed with the method of Pulse-Echo-overlap. Under the hydrostatic pressure ranged from 0.1 to 650 MPa, we measured ultrasonic velocity and attenuation coefficient of petroleum ether which is an important liquid-medium for transmitting pressure. An empirical formula of experimental data was obtained. The pressure dependence of ultrasonic velocity c is as follows: c=1. 063+6.77110-3p-2.28210-5p2+5.44910-8p3-6.07710-11p4+ 2.436 10-14p5 (0p700 MPa). In addition, we measured mass and compressed volume, getting the variation of density of petroleum ether with pressure: =0.6246+1.00710-3p-1.82310-6p2+2.54810-9p3-1.39310-12p4 (0p700 MPa). Finally, according to the equation c=(1/)1/2, the relation between hydrostatic pressure and adiabatic compressibility coefficient of petroleum ether were obtained.

High Pressure Investigation of Fluorescence Spectra and Levels for Gd2O2S:Eu

CHI Yuan-Bin, WANG Li-Zhong, LIU Shen-Xin, WANG Qiu-Ping

1994, 8(2): 87-98 . doi: 10.11858/gywlxb.1994.02.002

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Abstract:
The fluorescence spectrum of Eu3+ doped in Gd2O2S has been investigated in the spectral region 21 500～11 500 cm-1 at 77 K and 300 K. The 122 spectral lines measured at 77 K and the 96 lines at 300K have been assigned. Thirty five of the thirty nine Stark levels of 5D0~2, 7F0~6 multiplets were identified. The emission spectra were also measured under high pressures up to 15 GPa. It was found that all the lines observed change to longer wavelength and their intensities decrease with increasing pressure. The six levels of 5D0~2 descent more rapidly than the levels of 7FJ. The stark splittings of 5D2 and 7F2~5 multiplets increase, but the splittings of 5D1 and 7F1 multiplets decrease under pressure.

Polycrystalline Jadeite Gem

CUI Shuo-Jing, ZHAO Ting-He, YAN Xue-Wei, MA Xian-Feng, ZHU Yi-Bing, CHEN Jiu-Hua, ZHAO Wei

1994, 8(2): 99-106 . doi: 10.11858/gywlxb.1994.02.003

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Abstract:
In this paper we concluded give a comprehensive review of the progress and experiment results in jadeite jewel synthesis. The syntheses were carried out on the 5MN diamond Beltpress and on the 68MN cubic anvil press. The working curves of pressure and temperature on the cubic anvil press with high pressure cell 18 mm were given versus the dial plate pressure and heating power, respectively. The advantages and disadvantages were discussed in detail in the jadeite syntheses with the above two presses. The pressure and temperature gradient were also discussed in the high press synthesis cell.

Formation of the Metastable Phases in Pd-18 at.% Si Alloy Solidified under High Pressure

QIN Zhi-Cheng, LIU Yong, HUANG Xin-Ming, WANG Wen-Kui

1994, 8(2): 107-112 . doi: 10.11858/gywlxb.1994.02.004

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Abstract:
The solidification characteristic of liquid Pd-18 at.% Si alloy under high pressure was investigated by using X-ray diffraction, DTA, TEM, SEM and X-ray energy spectrum. The mixture of MS-Ⅰ and MS-Ⅱ metastable phases was obtained during the solidification of the alloy under 5.5 GPa with a cooling rate of 100 K/s. The former has a fee structure with the lattice parameter of a=0.388 3 nm. MS-Ⅰand MS-Ⅱ will transform into the equilibrium phase Pd and Pd3Si above 700 K.

Effect of Hydrogen on the Mechanical Behaviour of 22-13-5 Stainless Steel at Room Temperature

LONG Qi-Yi, FAN Cun-Gan, XING Zhong-Shu, LI Yi-Yi

1994, 8(2): 113-124 . doi: 10.11858/gywlxb.1994.02.005

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Abstract:
A stable fcc 22-13-5 stainless steel was hydrogen charged by exposing it in 9.8 MPa hydrogen gas at 300 ℃ for 14 days. The concentration of hydrogen was determined tobe 651 ppm. The mechanical testing at room temperature shows that after hydrogen charging the yield strength of the steel increases and the behaviour of transient creep and stress relaxation become more intensive in comparable conditions. All the results can be interpreted qualitatively and part of the creep results can be quantitatively calculated by the theory of mobile dislocation density proposed by Alden. The analysis indicates that the essential effects of hydrogen are to obstruct the movement of dislocation, so that the strength and the inelastic visccaity of the steel increase.

The Pressure and Temperature Dependence of Thermal Conductivity for Nonmetal Crystals

TANG Wen-Hui

1994, 8(2): 125-132 . doi: 10.11858/gywlxb.1994.02.006

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Abstract:
The pressure (p) and temperature (T) dependences of thermal conductivity (k) for nonmetal crystals are discussed. The equations KT=A+Bp at low pressures and kp＝A1+B1/T at low temperatures that fitted from experimental data are developed in theory, where A, B, A1 and B1 are fitting constants and the subscripts T and p refer isothermal and isobaric, respectively. The calculated results are in good accord with the experimental result. The responses of k under high pressure-high temperature and shock compressions are discussed as well.

The Numerical Simulation of Reflectivity of Aluminum Alloy Irradiated by Laser Beam

YANG Li-Bing, ZHANG Guan-Ren, LUO Fu, LIU Xu-Fa

1994, 8(2): 133-140 . doi: 10.11858/gywlxb.1994.02.007

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Abstract:
Based on the free electron model－the Drude/Fresnel theory, the variation of reflectivity of the aluminium surface under intense laser interaction is analyzed in this paper. From the numerical simulation of the relation of the aluminium conductivity with temperature, the instantaneous variations of the reflectivity at the aluminium surface in the solid, liquid and vapor states are conducted. The results are in accord with the experiments. When the laser power density is in the range from 1011~1015 W/cm-2, the numerical simulation results of the reflectivity with temperature are obtained according to the plasma model and the assumption of local thermal equilibrium (LTE). The results are approximate to the experimental results from abroad.

The Formation of Decagonal Quasicrystal and a New Crystalline Approximant in Al70Co15Tb5Ni10 Alloy

YU Ri-Cheng, XU Da-Peng, SU Wen-Hui, PANG Yan-Xin

1994, 8(2): 141-145 . doi: 10.11858/gywlxb.1994.02.008

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Abstract:
In this paper, samples of Al70Co15Tb5Ni10 in fusion state (1 450 ℃) were quenched with a cooling rate of 102 ℃/s under high static pressure (4.40 GPa). Decagonal quasicrystal and a new crystalline approximant were found in the samples for the first time. The structures of the decagonal quasicrystal and the new crystalline approximant were analyzed by TEM. Lattice parametere of the new crystalline approximant obtained from TEM observation are similar to those of the theoretical calculation.

Transportation of Carbon in High Pressure Flux and Its Effect on Diamond Growth

DING Li-Ye, LUO Xiang-Jie, Masao Wakatsuki, Yasushi Gohda, LI Wei

1994, 8(2): 146-152 . doi: 10.11858/gywlxb.1994.02.009

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Abstract:
Carbon supply is an important factor for nucleation and growth in diamond synthesis at high pressure and high temperature. It has been proved experimentally that carbon atoms of the source were dissolved in the flux and then transported towards the growing crystal mainly by diffusion in growing process. Furthermore, Convection did exist in the flux, and its effect on diamond growth should and could not be ignored.

A Study on the Kinetic Process of the Reverse-Transition of in Fe2SiO4 by Using Synchrotron Radiation and HT-DAC

WANG Li-Jun, Ming L C, Manghnani M H, Balogh J

1994, 8(2): 153-160 . doi: 10.11858/gywlxb.1994.02.010

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Abstract:
The method of studying the kinetic process of phase transition by means of in situ high pressure and high temperature X-ray diffraction with synchrotron radiation and high temporature DAC apparatus has been described. The results of the study on Fe2SiO4 reverse transformation from phase to phase under ambient pressure and various high temperatures (894, 926 ,948 and 993 K) are reported.

1994 Vol. 8, No. 2

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