高压物理学报

Mechanism for the Metallization of Solid Hydrogen under High Pressure

GOU Qing-Quan

1987, 1(1): 3-6 . doi: 10.11858/gywlxb.1987.01.001

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Abstract:
A mechanism for the metallization of solid hydrogen under high pressure is proposed on the basis of the theoretical analysis on the structural change of hydrogen molecule in solid state at high pressures. The experimental results from H. K. Mao, et al., about the Raman shifts of solid hydrogen under pressure, may be explained reasonably by the proposed mechanism.

Design Criterion for Ramp Wave Generator

JING Fu-Qian, LU Jing-De, LIU Cang-Li

1987, 1(1): 7-12 . doi: 10.11858/gywlxb.1987.01.002

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Abstract:
A design criterion for ramp wave generator is derived in this paper, which may be expressed as -[(2/3)+(g/2)] or -[(2/3)+(g/2)](cV/c2) (here is Grneisen coefficient, thermal expansion coefficient, c hydrodynamic sound speed, cV specific heat capacity at constant volume, g a material constant). Experimental results of a glass-ceramic sample showed that it may be used as a ramp wave generator, in which a shock wave could be transformed to an acceleration wave with front rise time of 800 ns at the position of 20 mm thickness.

Self-Consistent LMTO Calculations of the Equation of State at Zero Temperature for Copper

ZHANG Wan-Xiang, ZHANG Chun-Bin, LI Shao-Meng, CHEN Hao

1987, 1(1): 13-21 . doi: 10.11858/gywlxb.1987.01.003

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Abstract:
By using the self-consistent LMTO method which is built on the framework of density functional theory, the equation of state of fcc copper at zero temperature is calculated tin the region of compression ratio from 1 to 4.5. The comparisons of our results with those obtained by two semiempirical methods, those by Albers et al. and TFC data at high pressure show clearly that the results are reasonable. The further research will be able to provide the theoretical basis for correcting the semiempirical methods, find out the similarities and differences between energy band method and TFC theory and improve the understanding of the interaction of a many body system.

Pressure Behaviours of N and NNi Traps in Gap

ZHAO Xue-Shu, LI Guo-Hua, YANG Gui-Lin, WANG Bing-Sang, HAN He-Xiang, WANG Zhao-Ping, TANG Ru-Ping, HU Jing-Zhu, WANG Li-Jun

1987, 1(1): 22-31 . doi: 10.11858/gywlxb.1987.01.004

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Abstract:
It has been well known that localized electronic states in semiconductors are closely related to the electronic band structure. In fact, exploration of the interrelation between localized electronic states and the band structure represents a basic aspect of the electronic theory of semiconductors. The photoluminescence under high pressure provide an important means for investigating this interrelation. The pressure behaviors of N and NNi traps as well as some other shallow states in GaP have been investigated. We find at both room temperature and 77 K, when the pressure is lower than 3.3 GPa, the single nitrogen traps dominate the luminescence while above 3.3 GPa the free exciton becomes important, we observe nonlinear behaviors associated with the binding of an exciton bound to N and NNi traps. This work shows that the pressure behaviors of whole series of exciton bund to N and NNi in GaP can be quantitatively explained on the basis of the band Green's function taking account of pressure-dependent effective masses. This further confirmed by a Green's function treatment based upon a proper pseudo band structure.

Elastic Behaviour of the Gadolinium Gallium Garnet Crystal under High Pressure

WANG Ru-Ju, WANG Ji-Fang

1987, 1(1): 32-38 . doi: 10.11858/gywlxb.1987.01.005

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Abstract:
By means of the pulse echo overlap method, we have measured the velocities of ultrasonic wave propagating along different crystalline axes of the Gadolinium Gallium Garnet crystal (GGG). We have also measured the changes of the velocities with hydrostatic pressures and uniaxial stresses respectively. The second and third order elastic constants of GGG are obtained as follows: c11=3.04, c12=1.31, c44=0.94, c111=-17.97, c112=-12.86, c123=-1.06, c144=-2.11, c166=-3.29 and c456=-0.94, where the unit is 1011 N/m2. From these date we have calculated the Debye temperature and Gruneisen parameters (p,N) of GGG crystal from [011] to [111], [110] and [100].

Phase Transitions of Ge and Si under High Pressure

JIN Bi, ZHU Zai-Wan

1987, 1(1): 39-49 . doi: 10.11858/gywlxb.1987.01.006

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Abstract:
The covalent-metallic phase transitions of Ⅳ group elements (Ge, Si) are investigated in terms of pseudopotential theory. The calculated values of the pressure-volume relations. The transition pressure, the volume discontinuity and the superconducting transition temperature of the metallic phase show our theoretical results are in good agreement with the experimental data.

Molecular Dynamics Simulation of Polymorphous Transitions

CHEN Dong-Quan, XIE Guo-Qiang

1987, 1(1): 50-57 . doi: 10.11858/gywlxb.1987.01.007

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Abstract:
In this paper, temperature-induced polymorphous transitions for KCl and NaCl crystals at ＝0 are investigated using a molecular dynamics method. The change of the radial distribution function with temperature indicates that there occurs the structural transition from bcc to fcc. In order to choose potential parameters, we calculated the equations of state for KCl and NaCl at 0 K and studied pressure-induced polymorphous transitions from fcc to bcc. The transition pressures for NaCl and KCl are 18.8 GPa and 5.9 GPa respectively, which are in agreement with the experimental results so that those potential parameters seem resonable.

Monte-Carlo Investigation of Interaction of Relativistic Electron-Beam with Solid and Calculation of Its Mechanical Effects

YU Wan-Rui, ZHANG Ruo-Qi, LIU Ge-San

1987, 1(1): 58-70 . doi: 10.11858/gywlxb.1987.01.008

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Abstract:
The transport behaviour of electrons in alloy and composite materials is described and calculated in this paper. Investigations on the distribution of scattering angle and the energy loss are made. The calculation for the effects of the knock-on electrons and the spatial distribution of the electron energy dissipation are also presented. And finally the space-time distributions of pressure in solids are obtained from the thermodynamics properties of materials.

An Investigation on Electric Properties of the Polyaniline Complexes under High Pressure

CUI Shuo-Jing, XU Da-Peng, SU Wen-Hui, WANG Fu-Song, WANG Sheng-Long

1987, 1(1): 71-75 . doi: 10.11858/gywlxb.1987.01.009

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Abstract:
Electric properties of the polyaniline with large conjugated -bonds have been studied under high pressure. It shows that a minimum of electric resistance-pressure curve for the PAn-H+ occurs at p=3.2 GPa, which suggests that the PAn-H+ may be used as a pressure-calibration material of p=3.2 GPa. And voltage-current curves display nonlinear characterization at various pressure conditions.

Synthesis of Jewelry Jadeite at High Pressure and High Temperature

YAN Xue-Wei, MA Xian-Feng, NI Jia-Zan, QIAN Zheng-Nan, WANG Yi-Feng, SU Wen-Hui

1987, 1(1): 76-80 . doi: 10.11858/gywlxb.1987.01.010

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Abstract:
The synthesis of jewelry jadeite at pressures of 2.0~4.5 GPa and temperatures of 900~1 450 ℃ is described in this paper. The size of the synthetic jadeite is about 83 mm. The jadeite was synthesized from jadeite glass made at 1 350~1 550 ℃. By adding certain amounts of Cr3+, Cu2+, Co3+ cations, jadeite with emerald green, red and blue colours has been obtained respectively. The effects of pressure and temperature on the synthesis of jadeite are also discussed.

Experimental Studies on the Overdviven Detonation Events in Condensed Explosives

LI Da-Hong

1987, 1(1): 81-87 . doi: 10.11858/gywlxb.1987.01.011

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Abstract:
Maximum detonation pressure of 2.5 times than its C-J value was obtained in TNT/RDX (40/60) by using planar flyer impact technique. The equation of state of overdriven detonation product was derived as the form of p=Ak+A1(p-pJ) (p－detonation pressure, GPa, －density, kg/m3, A=J/kJ, pJ=27.06 GPa, J=2.3103 kg/m3, k=2.77, A1=2.710-3 GPa-1). The reflected shock state of the overdriven detonation product could be also described by the above equation satisfactorily.

Mass Ejection from Free Surface of Shock-Loaded Metallic Plates

ZENG Jian-Rong, ZHUANG Yi-He

1987, 1(1): 88-92 . doi: 10.11858/gywlxb.1987.01.012

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Abstract:
The mass ejection from free surfaces of aluminum alloy (Ly-12) and lead specimens under shock loading were measured using the piezelectric quartz crystal gauge technique. At shock pressure of 32 GPa, the ejected mass quantites of aluminum alloy with respec to the surface smooth finishes of 3.2 0.4 and 0.1 m are 1.53～3.28 g/m2, 0.2～0.3 g/m2 and 0.053～0.096 g/m2, respectively. At shock pressures of 13 and 47 GPa, the ejected mass quantites of lead with the surface smooth finish of 3.2 m are 26.4～42.4 g/m2 and 183～328 g/m2, respectively. Experiments also show that maximum shock pressure of about 20 GPa, the measured mass ejected under multiple shocks decreases remarkably in comparing with that under single shock. It is shown that the mass ejection is dependent on conditions of machining of free surface local melfing and the shock loading process.

Compressibility and Phase Transition of PZT-95/5 Ferroelectric Ceramics at High Pressure

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

1987, 1(1): 93-96 . doi: 10.11858/gywlxb.1987.01.013

PDF (689)

Abstract:
Using the experimental method established by the authors, the p-V relationships and the irreversible phase transition for PZT 95/5 ferroelectric ceramics have been studied at room temperature during the first, second and third compression up to 4.5 GPa.

1987 Vol. 1, No. 1

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