高压物理学报

Primary Research of Electrical Property of Pyrolyzed Polypyrrolone Film under Low Temperature and High Pressure

LIU Zhen-Xing, ZHANG Dian-Lin, PIAO Ming-Jun, WAN Mei-Xiang, LU Feng-Cai

1997, 11(1): 1-7 . doi: 10.11858/gywlxb.1997.01.001

PDF (769)

Abstract:
The temperature dependence of conductivity of polypyrrolone (PMDA-DAB) film pyrolyzed at different pyrolytic temperatures was measured as a function of the applied pressure. The obtained results indicate that the room temperature conductivity increases with the increase of the applied pressure and pyrolytic temperature. The pressure dependence of conductivity can be expressed by improved extended Mott expression. For the carbonization process (Tp800 ℃), the temperature dependence of conductivity can be expressed by the 3-Dimensional Variable Range Hopping (3D-VRH) model. For the graphitization process (Tp800 ℃),a modified 3D-VRH model was fitted.

Thermal Relaxation at Thin-Layer Interfaces: Its Significance to Shock Temperature Study

ZHOU Xian-Ming, JING Fu-Qian, HUANG Jian-Bin

1997, 11(1): 8-12 . doi: 10.11858/gywlxb.1997.01.002

PDF (644)

Abstract:
The thermal conduction problem of two interfaces for a sample/thin-layer/window configuration is solved for different initial temperature distribution, material thermal properties and different boundary conditions. Results reveal that the interface temperature history decreases sharply at first then approaches to a plateau within the observational time if the thickness of the thin-layer is very small (less than 1 mm) and the thermal diffusion coefficient is very large (greater than 10-4 m2/s). The amplitude of the temperature plateau depends on the initial temperature and the thermal diffusion coefficients of the sample or the window, does not relate to those of the thin-layer.

H-Derivative of the Function and the Fractal Dynamics

DONG Lian-Ke, WANG Xiao-Wei

1997, 11(1): 13-20 . doi: 10.11858/gywlxb.1997.01.003

PDF (705)

Abstract:
In this paper, Hausdorff measure of the function f(x) and H-derivative of the function f(x) under Hausdorff measure are given as follows: HD[f(x)]= supn{nj=1|f(xj)-f(xj-1)|D} and f(1)H(x,0)=limx0[|f(x0+ x)-f(x0+ x)|D]/(2x)D=|f(x0)|D. The system of evolution equation of fractal dynamics is u(1)Ht=k(x)u(2)Hxx-u(1)Hx, dD/dt=f(p1, p2), where the first equation is called the equation of fractal dynamics, and the second equation is called the evolution equation of Hausdorff dimension D.

Studies of 23 mm Electrothermal Chemical Launcher

ZHOU Zhi-Kui, CHEN Su-Nian, HAN Jun-Yu, LI Hong-Tao, SUN Chen-Wei, LI Chang-Qing, HUANG Yue

1997, 11(1): 21-26 . doi: 10.11858/gywlxb.1997.01.004

PDF (634)

Abstract:
The system of 23 mm electrothermal chemical launcher is described in this paper. It involves the power supply, control system, launching device and measuring technology. It is analyzed that the concentration of the hydrogen peroxide influences the launching property in the mixture of hydrogen peroxide with octane. The experimental results of several liquid propellant prescriptions used are presented.

Effects of the Shock Temperature and Its Effect on Phase Transition of Anatase TiO2

XU Kang, HE Hong-Liang, TAN Hua, LIU Jian-Jun

1997, 11(1): 27-31 . doi: 10.11858/gywlxb.1997.01.005

PDF (663)

Abstract:
A simple method was introduced to reduce the shock temperature of porous solid sample under shock wave loading by filling the sample with liquid paraffin. Anatase TiO2 was used as an example, results were compared for samples not filled and filled with liquid paraffin. In the former case, rutile is the main product, that is, phase transition occurs under the action of high shock temperature, while for the sample filled with liquid paraffin, -TiO2 (high pressure phase) is the main product, which shows that high pressure plays the dominant role, and the temperature produced by shock waves is much lower than that in the former case and only plays a minor role in the phase transition of anatase.

Theoretical Research on Temperature Dependence of the Specific Heat at Constant Volume for Liquid Metals

TANG Wen-Hui

1997, 11(1): 32-38 . doi: 10.11858/gywlxb.1997.01.006

PDF (1074)

Abstract:
Based on the experimental results, Grover[1] presented an approximation formula for the specific heat at constant volume of liquid metals versus temperature: cV3R-RT/Tm, where T is the temperature, Tm is the melting temperature, R is the gas constant, is an empirical constant, with value of 0.11~0.24, its average value is about 0.15. In this paper, the approximation relation is deduced by using the Lennard-Jones-Devonshire theory.

A High Sensitive Transient Optic Pyrometer

LUO Jiao-Ming

1997, 11(1): 39-45 . doi: 10.11858/gywlxb.1997.01.007

PDF (600)

Abstract:
A new pyrometer has been developed, which uses: (a) dichroic splitters as pyrometer beamsplitters which increases the splitter efficient from about 25% (for a half-transmit half-reflect beamsplitter) to about 85%; (b) 50 dB amplifiers with an input electrical resistance less than 100 and response time less than 5 ns improve the response of the original version of the pyrometer, and (c) a tungsten standard lamp as the pre-experimental calibration standard light irradiance source which makes the pre-shot calibration more convenient and reliable. As an example to test its ability, temperature measurements for single crystal sodium chloride shocked to pressures from 36 to 60 GPa were conducted, temperatures of 1 500K to 3 600 K were calculated from the recorded light radiance signals.

Electrical Properties and Phase Transitions in -BaB2O4 at High Pressure

BAO Zhong-Xing, LIU Cui-Xia, HUANG Chao-En, LIU You-Chen, CHEN Hong, WU Fei

1997, 11(1): 46-49 . doi: 10.11858/gywlxb.1997.01.008

PDF (745)

Abstract:
The capacitance, resistance-pressure relationships for the low temperature phase of barium metaborate (-BaB2O4) have been studied at room temperature at pressure up to 16 GPa in a diamond anvil cell using capacitance and resistance measurements. Experimental results indicate that anomalous changes in capacitance with pressure occurring near 2.1, 4.6, 6.4, 8, 9.5 and 10.7 GPa. This shows the changes of structure or state in the interior of -BaB2O4 at these pressures i.e., that -BaB2O4 may undergoes phase transition. In the present work, it is known from X-ray diffraction analysis on the -BaB2O4 sample after releasing pressure from 12 GPa that the sample has become amorphous. This shows that the -BaB2O4 sample has already become amorphous state at higher pressure, and kept it after releasing. The amorphous transition pressure is about 11～12 GPa.

Experimental Study on Measuring Sound Velocities of Jilin Aerolite at High Pressure

YU Quan-You, WANG Gui-Chao, JIN Xiao-Gang, TIAN Jian-Hua, Lü Xiu-Sheng, HE Li-Hua

1997, 11(1): 50-55 . doi: 10.11858/gywlxb.1997.01.009

PDF (722)

Abstract:
The theory, technology and results of measuring sound velocity of Jilin aerolite at high pressure by using radiometry and using transparent material as the window in the pressure range from 42.2 to 113.2 GPa are described in this paper. According to the relation between sound velocity of Jilin aerolite and shock pressure the phase transition of Jilin aerolite near 65 GPa can be determined.

Study on Stress in Chemical Vapor Deposite (CVD) Diamond Films

TANG Bi-Yu, Jin Jiu-Cheng, LI Shao-Lü, ZHOU Ling-Ping, CHEN Zong-Zhang

1997, 11(1): 56-60 . doi: 10.11858/gywlxb.1997.01.010

PDF (1061)

Abstract:
The stress in diamond films by the hot filament assisted chemical vapor deposition process was studied by X-ray diffraction technique. The investigation shows that the thermal stress is compressive in the temperature range studied and the intrinsic stress is tensile. The influence of various experimental parameters on the stress in films was analyzed.

The Effects of Thickness and Back Surface of Diamond Film on Thermal Conductivity

GU Chang-Zhi, JIN Zeng-Sun, Lü Xian-Yi, ZOU Guang-Tian, ZHANG Ji-Fa, FANG Rong-Chuan

1997, 11(1): 61-65 . doi: 10.11858/gywlxb.1997.01.011

PDF (900)

Abstract:
In this paper, we described the effects of the thickness and back surface of diamond film on thermal conductivity. Diamond films with different thicknesses were synthesized by MWPCVD method. The results show that high thermal conductivity diamond film can be acquired with thickened film and removed back surface (SiC).

Theoretical Studies on Hugoniot Curves of Graphite

YANG Xiang-Dong, ZHANG Hong, ZENG Yong, WU Bao-Jian, CHENG Xin-Lu, HU Dong, JING Fu-Qian

1997, 11(1): 66-69 . doi: 10.11858/gywlxb.1997.01.012

PDF (703)

Abstract:
In this paper we have studied equation of state of graphite and diamond under high pressure with a unified scaling model. Simple additivity of the energy terms is assumed and the cold pressure curve is a modified Birch form. The lattice thermal effects can be computed by the Einstein model while the electronic contributions are represented by the low temperature form of heat capacity and energy. Using the above model, we have determined the expansion curves and Hugoniot curves of graphite under different initial conditions.

Study on the Effect of the Phase Transition of Pyrophyllite on the Resistance of the Heating Graphite Tube in High Pressure Reaction Cell

LUO Xiang-Jie, LUO Bo-Cheng, LIU Qiang, DING Li-Ye

1997, 11(1): 70-74 . doi: 10.11858/gywlxb.1997.01.013

PDF (607)

Abstract:
Under high temperature and high pressure (HTHP), we find that the process of the phase transition of pyrophyllite causes abnormal change of the resistance of the graphite tube indirectly heating the reaction cell. Several laws of the phenomenon and the interior relations between the laws and the phase transition of pyrophyllite were analyzed. The experiments make it possible to observe and study the law of the phase transition of pyrophyllite in the process of HTHP.

Research of Modification on Shocked Aluminium Nitride Powder through X-Ray Diffraction

HAN Wei, LU Fang-Yun

1997, 11(1): 75-80 . doi: 10.11858/gywlxb.1997.01.014

PDF (669)

Abstract:
The changes of microstrain and dislocation density caused by shock wave on aluminum nitride ceramic powder have been researched, by X-ray diffraction method the relationship between the microstrain and the size of the crystallite is obtained. According to Warren-Averbch analysis, this means that the size of the coherent scattering region is far smaller than the size of the granula. It demonstrates that the shock wave treatment can generate large amount of crystal lattice defects in aluminum nitride.

1997 Vol. 11, No. 1

Login in

NewsMore

LinksMore