Fullerenes have been converted to diamond crystals with the size of 0.1 mm at 5.0-5.5 GPa and 1400°C, using NiMnCo catalyst. They are similar to graphite in the growing phenomena. They are transformed into diamond directly without being graphitized first.

Yanzhang Ma;广田 邹;Haibin Yang;Jinfang Meng

Applied Physics Letters

1994

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.

Pinwen Zhu;Yoshio Imai;Yukihiro Isoda;Yoshikazi Shinohara;晓鹏 贾;广田 邹

Journal of Physics Condensed Matter

2005-11-23

The effect of external quasi-hydrostatic pressure on the inverse spinel structure of LiCuVO₄ was studied in this paper. High-pressure synchrotron X-ray diffraction and Raman spectroscopy measurements were carried out at room temperature up to 35.7 and 40.3 GPa, respectively. At a pressure of about 20 GPa, both Raman spectra and X-ray diffraction results indicate that LiCuVO₄ was transformed into a monoclinic phase, which remained stable up to at least 35.7 GPa. Upon release of pressure, the high-pressure phase returned to the initial phase. The pressure dependence of the volume of low pressure orthorhombic phase and high-pressure monoclinic phase were described by a second-order Birch-Murnaghan equation of state, which yielded bulk modulus values of B₀ = 197(5) and 232(8) GPa, respectively. The results support the empirical suggestion that the oxide spinels have similar bulk modulus around 200 GPa.

Heng Nan Liang;Chun Li Ma;Fei Du;Qi Liang Cui;广田 邹

Chinese Physics B

2013-1

We show the dependence of the disappearance pressures of ruby R-line fluorescence on the wavelengths of the incident laser beams under quasihydrostatic pressure up to 90 GPa and discuss the valid pressure range of the ruby gauge. The degree of hydrostaticity of the argon pressure medium has been determined at the same time.

Zhenxian Liu;Qilian Cui;广田 邹

Physics Letters, Section A: General, Atomic and Solid State Physics

1990-1-1

Radar absorbing materials of nickel-coated carbon fiber (NCF) and nickel-coated flake graphite (NFG) were fabricated by electroless plating. Sufficient activation sites were vital to deposit a continuous and uniform coating layer. The morphology of the CF (FG) and NCF (NFG), Pd element content on the CF surface, the element components and the phases in the coating layer, magnetic properties of the NCF and NFG were examined by FESEM, EDS, XRD and VSM, respectively. The absorption properties of the samples were measured over the frequency range of 8-18 GHz by the RAM reflectivity far field RCS method. NCF and NFG exhibit good absorption performances in high frequency. Specifically, the reflection loss (R.L.) of NCF (30%) less than -10 dB begins from 14.4 to 18 GHz and the R.L. is below -14 dB at 18 GHz.

Yuzun Fan;Haibin Yang;Xizhe Liu;Hongyang Zhu;广田 邹

Journal of Alloys and Compounds

2008-8-11

By using aluminium nanopowder prepared by wire electrical explosion, pure monophase NiAl compound with fine crystallites (<10 μm) and good densification (98% of the theoretical green density) was successfully fabricated by means of self-propagating high-temperature synthesis (SHS) under a high pressure of 50 MPa. Investigation shows that, due to the physical and chemical characteristics of the nanoparticles, the SHS reaction mode and mechanism are distinct from those when using conventional coarse-grained reactants. The SHS reaction process depends on the thermal conditions related to pressure and can occur at a dramatically low temperature of 308°C, which cannot be expected in conventional SHS reaction. With increasing pressure, the SHS explosive ignition temperature (T_ig) of forming NiAl decreases due to thermal and kinetic effects.

Shushan Dong;Ping Hou;Haiyong Cheng;Haibin Yang;广田 邹

Journal of Physics Condensed Matter

2002-11-11

The catalytic effects of copper-based alloys in diamond growth have been investigated. A single crystal of diamond has been obtained by the temperature gradient method (TGM), using Cu-Mn-Co and Cu-Co alloys as catalysts. It was found that the melted Cu-Mn-Co and Cu-Co alloys show low viscosity. The eutectic temperatures of these two alloys with graphite were between 1130 and 1150°C, and the temperature of the transition to diamond was over 1300°C, at 5.5 GPa. High-quality diamond could not be obtained in Cu-Co alloy by the TGM. Our results suggest that adding Cu to a catalyst cannot decrease the reaction temperature for diamond growth.

Lixue Chen;Pinwen Zhu;Hongan Ma;晓鹏 贾;Masao Wakatsuki;广田 邹

Journal of Physics Condensed Matter

2002-11-11

The decomposition behaviour of CuO is studied at high temperature and high pressure. Experimental pressure and temperature determine the results. In the region of higher temperature and pressure (≥5.5 GPa, ≥1400°C), the product is just copper. In the region of lower temperature and pressure (<5.0 Pa, <1100°C), CuO does not decompose. Between the two regions, the product is a mixture of Cu and Cu₂O or a mixture of Cu₂O and CuO.

G. Z. Ren;T. C. Zhang;X. C. Wang;H. A. Ma;X. B. Guo;J. T. Liu;广田 邹

Journal of Physics Condensed Matter

2002-11-11

Energy-dispersive x-ray diffraction studies are carried out on the distorted perovskite La_0.5-xBi_xCa_0.5MnO₃ (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25) under high pressure at room temperature. The unusual expansion of the 202-040 d-spacing under pressure is observed, and the change of the Mn-O bond angle brings about the disappearance of the basal-plane Q₂ distortion mode. With doping content increasing, a shoulder peak appears in the observed main peak of La_0.25Bi_0.25Ca_0.5MnO₃ at 43.9 GPa. The pressure-enhanced interactions between charge, orbital, and coupling with the lattice distortion are discussed.

Xin Wang;Qiliang Cui;Yuewu Pan;广田 邹

Journal of Physics Condensed Matter

2002-11-11

Iron carbide without any graphite was studied under high pressure and high temperature (HPHT); diamond layers were obtained both on diamond and on cubic boron nitride seeds at 5.5 GPa and 1700-1750 K. The results showed that transition-metal carbide was the main intermediate in the course of the transformation form graphite to diamond under HPHT.

Xun Li;Chunxiao Gao;Zhaoyin Hao;Peng Liu;Musen Li;广田 邹;Shuyu Cheng;Kaijia Cheng

Journal of Physics Condensed Matter

2002-11-11