The composition-dependent thermoelectric properties of lead telluride (PbTe) doped with bismuth telluride (Bi 2Te 3), antimony telluride (Sb 2Te 3) and (BiSb) 2Te 3 have been studied at room temperature. All the samples exhibit small thermal conductivity. The figures of merit, 7.63, 1.03 and 8.97×10 ^-4, have been obtained in PbTe with these dopants, respectively. These values are several times higher than those of PbTe containing other dopants with small grain sizes. The high thermoelectric performance is explained by electronic topological transition induced by alloying. The results indicate that these dopants are effective to enhance the thermoelectric performance of PbTe. ©2005 Chinese Physical Society and IOP Publishing Ltd.

Zhu Pin-Wen;Imai Yoshio;Isoda Yukihiro;Shinohara Yoshikazi;Jia Xiao-Peng;Zou Guang-Tian

Chinese Physics Letters

2005

For the first time, the fullerenes were applied to butadiene polymerization. The behavour of butadiene polymerization with novel fullerenes supported neodynium catalyst system were investigated. The effects of polymerization conditions on the catalytic activity were also examined. It revealed that the function of the fullerenes might is a ligand and a supporter and the mole ratio of Al/Nd and C60/Nd. The aging temperature and polymerization temperature had a relatively effect on catalytic activity. The catalyst system showed much better stability in catalytic activity for aging time and aging temperature as compared to general neodynium and nickle catalyst systms.

Zhao Chunying;Chen Dianbao;Zhong Chongqi;Dong Wenhuan;Xu Ling;Tang Xueming;Yang Haibin;Li Minghui;Zou Guangtian

Acta Polymerica Sinica

1996

The quasi-four-probe resistivity measurement on the microcrystal of 1,4-bis[(4-heptyloxyphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-3) is carried out under variable pressure and temperature conditions using a diamond anvil cell (DAC). Sample resistivity is calculated with a finite element analysis method. The temperature and pressure dependences of the resistivity of OXD-3 microcrystal are measured up to 150°C and 15 GPa, and the resistivity of OXD-3 decreases with increasing temperature, indicating that OXD-3 exhibits organic semiconductor transport property in the region of experimental pressure. With an increase of pressure, the resistivity of OXD-3 first increases and reaches a maximum at about 8 GPa, and then begins to decrease at high pressures. From the x-ray diffraction data in DAC under pressure, we can conclude that the anomaly of resistivity variation at 8 GPa results from the pressure-induced amorphism of OXD-3. © 2005 IOP Publishing Ltd.

Luo JiFeng;Han YongHao;Gao ChunXiao;Zou GuangTian;Tang BenCheng;Li Min

Journal of Physics D Applied Physics

2005

TiO 2 /CoFe 2 O 4 composite nanoparticles with a core-shell structure have been obtained. The core CoFe 2 O 4 nanoparticles were synthesized via co-precipitation method, and the shell TiO 2 nanocrystals were derived via sol-gel technology followed by heat-treatment at 450 °C. The morphology and the crystalline structure of composite nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction, respectively. The as-prepared composite particles can be utilized as a magnetic photocatalyst, which can be fluidized and recovered by an applied magnetic field enhancing both the separation and mixing efficiency for recyclable fluids. Magnetic properties and photocatalytic activities of these powders have been evaluated. © 2005 Elsevier B.V. All rights reserved.

Fu Wuyou;Yang Haibin;Li Minghui;Yang Nan;Zou Guangtian;Li Minghua

Materials Letters

2005

Although there are many reports on PbTe-SnTe and Bi2Te 3-Sb2Te3 systems with improved thermoelectric performance due to reduced lattice thermal conductivity, only few experimental data exist on PbTe-Sb2Te3 system. In this report, the composition-dependent thermoelectric properties of PbTe doped with Sb 2Te3 have been studied at room-temperature. It is worth noting that the lattice thermal conductivity is only about 1 W/K-m as the contents of Sb2Te3 is larger than 0.8 mol%. In addition, the figure of merit shows a maximum value of 1.03 × 10^-3 K ^-1 with the content of Sb2Te3 at 0.8 mol% which is the highest value obtained in doped bulk PbTe samples and is several times higher than that of PbTe containing other dopants with small grain sizes. This confirms that Sb2Te3 is one of the best dopants for PbTe to enhance its thermoelectric performance. © 2005 The Japan Institute of Metals.

Zhu Pinwen;Imai Yoshio;Isoda Yukihiro;Shinohara Yoshikazi;Jia Xiaopeng;Zou Guangtian

Materials Transactions

2005

The structural transformations occurring to water from low-density (LDW) to high-density (HDW) regimes have been studied by Brillouin scattering for the first time at temperatures up to 453 K and at pressures up to the solidification point. At ambient temperature (293 K) a discontinuity in pressure response of the sound velocity is observed. Furthermore, there are evident breaks in the linear behavior of log10 C11 versus log10 (ρ ρ 0) when pressure increases up to 0.29, 0.21, and 0.19 GPa at the temperature of 293, 316, and 353 K, respectively. It is supposed to indicate the structural transition from LDW to HDW, and the possible transition boundary between LDW and HDW is in good agreement with the molecular-dynamics simulation. © 2005 American Institute of Physics.

Li Fangfei;Cui Qiliang;He Zhi;Cui Tian;Zhang Jian;Zhou Qiang;Zou Guangtian;Sasaki Shigeo

Journal of Chemical Physics

2005

We report the enhanced thermoelectric properties of PbTe alloyed with antimony telluride (Sb2Te3). The resistivities and absolute values of the Seebeck coefficient for PbTe alloyed with Sb 2Te3 increase while the thermal conductivities decrease with rising temperature. A maximum figure of merit, ZT, of 1.17 has been achieved for PbTe alloyed with 0.8 mol% Sb2Te3 at 560 K. This value is about 30% higher than the ones reported previously for bulk PbTe. The enhanced thermoelectric properties may be due to the low thermal conductivities which are induced by alloying with Sb2Te3 and much smaller than that reported for bulk PbTe. © 2005 IOP Publishing Ltd.

Zhu Pinwen;Imai Yoshio;Isoda Yukihiro;Shinohara Yoshikazi;Jia Xiaopeng;Zou Guangtian

Journal of Physics Condensed Matter

2005

Superhard MgB2 polycrystalline compact with good electrical conductivity was synthesized in a cubic anvil high-pressure apparatus. The synthesis conditions of HPHT are 5.5 GPa and 700~1000°C. Observed by an optical microscope (OM), the sample has brown metallic shine. X-ray diffraction (XRD) data were collected to study the crystal structure. X-ray diffraction spectra show that MgB2 has typical hexagonal structure, and the space group is P6/mmm (191), the cell parameter is a =0. 308 nm, c = 0.352 nm. At ambient state, the Vickers hardness, bulk density, and electrical resistance of the synthesized sample were measured. The results show that tne Vicker's Hardness (Hv) of the sample is 4109.5 kgf / mm², and the electronic conductivity is 2.42 × 10^-6Ωm.

Ma Hongan;Chen Lixue;Quo Weili;Zang Chuanyi;Jia Xiaopeng;Qin Jieming;Zou Guangtian

Jingangshi Yu Moliao Moju Gongcheng Diamond and Abrasives Engineering

2005

We generalize a path integral Monte Carlo formula to investigate the phase boundary between the fractional quantum Hall liquid and the Wigner crystal for a two-dimensional electron (fermion) system in the presence of strong magnetic fields and at low temperatures. At very low temperature, the state of the system is found to be a solid at filling factors ν=1 7, 1 9, and 1 11, while the state remains liquidlike at ν=1 3 and 1 5. The temperature-density phase diagrams are obtained at low filling factors. At ν=1 7 and a fixed electron density, the calculated melting temperature is ∼220mK, in good agreement with some experimental results. The nature of the phase transition is suggested to be continuous. © 2005 The American Physical Society.

He W. J.;Cui T.;Ma Y. M.;Chen C. B.;Liu Z. M.;Zou G. T.

Physical Review B Condensed Matter and Materials Physics

2005

We have successfully synthesized C 70 rods in nano/sub-micrometers scale by evaporating solvent method. The diameter of the as grown C 70 rods is ~500 nm, and the length is ~10 μm. The EDXD pattern and Raman spectroscopy for as-grown sample indicate that the as grown C 70 rod is in hcp structure. The pressure-induced structural phase transition has been studied by using DAC combined with EDXD and Raman spectroscopy methods under quasi-hydrostatic pressure up to 26.1 GPa. It is found that hcp structure transforms into amorphous phase for C 70 rods in the pressure range from 23.3 to 26.1 GPa, which is higher than the transformation pressure for bulk C 70 crystals. The phase transition is irreversible and it is induced by the collapse of C 70 cage.

Wang Lin;Liu Bing-Bing;Liu De-Di;Hou Yuan-Yuan;Yao Ming-Guang;Zou Guang-Tian;Li Hui;Luo Chong-Ju;Li Yan-Chun;Liu Jing;Sundqvist B.

Kao Neng Wu Li Yu Ho Wu Li High Energy Physics and Nuclear Physics

2005