高压物理学报

Crystallization Process of Amorphous SrB4O7：Eu2+ under High Pressure and High Temperature

LIU Hong-Jian, LIU Wei-Na, GUAN Zhong-Su, SUN Shu-Lan, SU Wen-Hui

1994, 8(3): 161-165 . doi: 10.11858/gywlxb.1994.03.001

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Abstract:
The crystallization process of amorphous SrB4O7 under high pressure were studied by using X-ray diffraction and Eu2+ emission spectra. X-ray diffraction results show that under the pressure of 5.0 GPa, at 200 ℃ there exists a few small diffraction peaks with very low intensity, indicating trace crystallization. At 600 ℃, however, the crystallization process basically completes, it becomes a mixture of two phases, one is an orthorhombic SrB4O7 and the other cubic SrB4O7; as the temperature increasing to 1 000 ℃, the sample crystallizes to single phase SrB4O7 with a structure the same as the powder crystal sample's prepared under atmosphere. The above results were further confirmed by Eu2+ emission spectra obsenations: the intensity of Eu2+ emission peak at 370nm increased obviously with the crystallinity of the sample.

Fractal Descriptions of Some Fracture Problems

LEI Wei-Sheng, CHEN Bing-Sen

1994, 8(3): 166-171 . doi: 10.11858/gywlxb.1994.03.002

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Abstract:
This paper presents fractal descriptions of critical crack extension force, crack branching and crack propagation speed. Besides the measurements of fractal dimension of fractured surfaces is discussed.

Parameter Selection of Indirectly Charging Magnetic Flux Compression Generator

XIE Wei-Ping, GONG Xing-Gen, SUN Qi-Zhi, SUN Cheng-Wei

1994, 8(3): 172-176 . doi: 10.11858/gywlxb.1994.03.003

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Abstract:
In this paper, an indirectly charging magnetic flux compression generator (MFCG) is theoretically investigated from circuit equation. It shows that the inductance L1 and capacitance C0 of charging circuit must satisfy the relation (L1C0)1/2T when an indirectly charging MFCG is designed; coupling MFCG can amplify the initial magnetic flux; the wave shape of current pulse of MFCG is influenced by the capacitance of charging circuit. All this result is valuable to the design of MFCG.

Investigations of Different Type of Glass by Ultrasonic Interferometer Technique at Room Temperature and High Pressure

WANG Ru-Ju, LI Feng-Ying, XU Ji-An, Manghnani M H, XIE Hong-Sen

1994, 8(3): 177-183 . doi: 10.11858/gywlxb.1994.03.004

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Abstract:
The ultrasonic interferometer techniques－phase comparison method, pulse echo overlap, pulse superposition and phase detection have been combined together to study the elastic properties of three types of glass under different pressures and room temperature. These glasses are named by silicate glass (water white glass and window glass) and polystyrene. The results show that there exists a big difference in the ultrasonic velocities, attenuations and elastic constants at room temperature between silicate glass and polystyrene. At high pressure, the pressure dependences of velocities are similar for both types of silicate glass: the velocities of longitudinal waves increase as pressure increased, while the velocities of shear waves decrease linearly, and the attenuations in longitudinal waves also increase with pressure. However attenuations of shear waves for the two types of silicate glass vary oppositely with pressure, the attenuation goes up with pressure for water white glass, and goes down for window glass. The results obtained by above techniques are consistent, and is in agreement with Brillouin scattering data at corresponding pressure range.

The XPS Study of CeTbO3+ Synthesized by High Pressure and Temperature

LI Li-Ping, WEI Quan, LIU Hong-Jian, ZHENG Da-Fang, SU Wen-Hui

1994, 8(3): 184-189 . doi: 10.11858/gywlxb.1994.03.005

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Abstract:
The samples of CeTbO3+ synthesized by high pressure and high temperature were studied by XPS. It is found that Tb4+ ion begins to transform to Tb3+ at about 600 ℃ and Ce4+ to Ce3+ about 800 ℃. The single phase compound of CeTbO3+ having a fluorite structure is formed at 1000 ℃, in which the Ce ions exist in a mixed valence state of Ce3+ and Ce4+. The existence of Ce3+ ions in compounds can be determined by the shift of the 888 eV photoelectron peak and the change of the relative intensity between this peak and the 882 eV peak. The stability of CeTbO3+ synthesized by high pressure and temperature with the time was investigated.

The Thermal Shock Wave Induced by X-Ray and Electron Beam Radiation and the Compressive Stress Wave

Zhou Nan

1994, 8(3): 190-199 . doi: 10.11858/gywlxb.1994.03.006

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Abstract:
The paper describes the characteristic difference between the thermal shock wave induced by X-ray and electron beam radiation and the compression wave due to explosion and high-velocity impact, results of which are useful for the investigation and simulation of the thermal shock waves.

MoSi2 Band Gap Modulation at High Pressure

ZHANG Hai-Feng, LI Yong-Ping, HUANG Xin-Tang

1994, 8(3): 200-204 . doi: 10.11858/gywlxb.1994.03.007

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Abstract:
The electronic structure of transition metal disilicides MoSi2 at high pressure was studied by using LMTO-ASA method. All the relativistic effects except spin-orbit coupling were considered. The results indicate that, with the compressibility increasing, the width of valence band became wider which shows the interaction between Mo d electrons and Si p electrons became larger, the cohesion of crystal increases. Should we say that, this result is conflict to the rule of metallization of nonconductors at high pressure.

Simulation Study on Laser-Induced Spallation in Aluminum

ZHANG Wan-Jia, WANG Wu, ZENG Yuan-Jin, SONG Chun-Xiang

1994, 8(3): 205-212 . doi: 10.11858/gywlxb.1994.03.008

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Abstract:
The occurrence of spall in target caused by laser-driven shock wave depends on the power density of the beam, the induced pressure pulse duration, the target thickness and the target material parameters. The propagation attenuation of a triangular compressive wave and the time-dependence of spallation are discussed in this paper. Based on the gas-gun experimental simulation technique, an incident laser with power density of 103 W/cm2 and energy density of 103 J/cm2 was proposed as the threshold for causing spallation in LY-12 Al target with a thickness of 2 mm.

Dynamic Properties of LF-6 and LY-12 Aluminum Alloy under High Temperature－High Temperature Shearing Modulus Measurement

WANG Chun-Kui

1994, 8(3): 213-219 . doi: 10.11858/gywlxb.1994.03.009

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Abstract:
Investigations of high temperature shearing medulus with the torsional Hopkinson bar method, of LF-6 and LY-12 aluminum alloy at temperatures up to 440 ℃, is introduced, elastic modulus and Poisson ratio of LF-6 aluminum alloy are reported. Results show that these dynamic properties, especially at high temperatures, are generally higher than their static ones, LF-6 and LY-12 aluminum alloy are sensitive to both temperature and loading rates, but their sensitivity to temperature at high strain rates is less than that in static loading rate. In this paper relations of the shearing modulus and elastic modulus with temperature are given.

The Preparation of Diamond Film with the Method of Electron Assisted Chemical Vapor Deposition

GU Chang-Zhi, WANG Chun-Lei, JIN Zeng-Sun, Lü Xian-Yi, ZOU Guang-Tian

1994, 8(3): 220-223 . doi: 10.11858/gywlxb.1994.03.010

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Abstract:
A high quality diamond film which has a high growth velocity has been synthesized on Si substrates by means of the electron assisted chemical vapor deposition method. The maximum growth velocity is 7 m/h and the growth areas of diamond film is 40 mm. The growth characteristics of the high quality diamond film were studied.

Studies on Regenerated Catalyst of Electrodeposition and Diamond Synthesis

YANG Chang-Yuan, GUO Bi-Hong, DING Li-Ye, GOU Qing-Quan

1994, 8(3): 224-228 . doi: 10.11858/gywlxb.1994.03.011

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Abstract:
Catalyst plays an important role in the diamond synthesis by static pressure method. It can lower the pressure and temperature required to transform graphite into diamond. The smelted Ni-Mn-Co catalyst is widely used in China. In this paper, a new kind of catalyst is made according to Gou Qingquan's 3 optimization principles for catalyst. When the Ni-Mn-Co catalyst in synthetic bar is removed by quick electrolysis, a thin piece of metal plate, which is level and regular in thickness, is obtained on the negative electrode by control ling electrolytic conditions. The chemical analysis shows that its composition is Ni-Co-Fe, a good catalyst according to Gou's 3 principles, and is called regenerated catalyst of electrodeposition. Large amount of coarse and fine diamond has been synthesized by using the regenerated catalyst of electrodeposition with the cubic type press of 67.84 MN (made in China). TG analyses and strength tests show that the quality of the synthesized diamond is satisfactory. Besides the catalyst can be recycled to use, deducing the cost of diamond production and raising the profits.

The Nucleation Mechanism of Substrates Surface Defects in Low Pressure Vapor Deposition of Diamond Thin Films

YANG Guo-Wei

1994, 8(3): 229-236 . doi: 10.11858/gywlxb.1994.03.012

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Abstract:
To promote diamond nucleation density, introduction of defects on the substrate surface is an effective method in low pressure vapor deposition of diamond thin film growth. However, little studies in this field have been made so far. Based on our experiments, we present in the paper the diamond nucleation mechanisms of the groove defects on the substrate surface. The size of the groove defects is of key importance for the diamond nucleation: An appropriate size of the groove defects can effectively promote the nucleation. Finally, we studied the significance of the theory in the controlling of diamond nucleation density via the surface defects on the substrate.

High Pressure Study on Wollastonite

YANG Jing-Hai, YAO Bin, LIU Hong-Jian, GENG Yi-Zhi, SU Wen-Hui, ZHANG Ju-Yuan

1994, 8(3): 237-240 . doi: 10.11858/gywlxb.1994.03.013

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Abstract:
The wollastonite (CaSiO3 ) synthesized by high temperature (HT) under atmospheric pressure (AP) has a triclinic structure while the natural wollastonite with high purity originating from Dading Mountain, Lishu, Jilin Province, China, has a white chain-like structure of monoclinic type. Pressure-induced phase transformation of this natural wollastonite above and the wollastonite synthesized directly from raw materials by HP and HT were firstly investigated. Results show that the natural wollastonite treated under HP (4.6～5.0 GPa) and HT (1 200～1 250 ℃) transforms to partially translucent cubic crystal with dark rose colour and the one synthesized directly by HP (3.8～4.3 GPa) and HT ( 1 050～1 100 ℃)to the same structure and with similar appearance. SEM analysis indicates that, for the natural wollastonite, the contents of SiO2 and CaO are 50.8% and 48.1% respectively, while the synthetic one, both treated and synthesized directly by HP and HT, has the contents 51.35% and 48.15% respectively.

1994 Vol. 8, No. 3

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