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【期刊论文】Investigation of the off-diagonal Seebeck effect and Peltier effect on textured YBaz Cu3 O7-δ*
何振辉, Z.H. He a, F.Q. Zhonga, y.y. Luoa, M. Wub, W. Gavalekb, K.F. LiangC, and P.C.W. Fungc
Physica C 282-287 (1997) 1247-1248,-0001,():
-1年11月30日
Both of the off-diagonal Seebeck effect and the off-diagonal Peltier effect were investigated with the use of the same textured sample YBa2 Cu3 07-δ (Y-123) and the same experimental setup. The reliability of the measurement is studied by applying different heat-conductive mediums. The flatness of both of the sample and the heat-conducting block, and the matching between them are found very important for the reduction of the heat resistance. The annealing effect on the S is also studied and found in accordance with that studied by the thermoelectric power.
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【期刊论文】Introduction of the ultrafine MgO to the high Tc melt-texture YBa2 Cu3 O7-δ*
何振辉, Z.H. He, X.M. Xiong, Y.S. Lai, C.H. Liu, Y.Y. Luo, and J.X. Zhang
Physica C 282-287 (1997) 547-548,-0001,():
-1年11月30日
idth at half-height of powder X-ray diffraction, the MgO powder was about 20nm in size on average. A supersonic vibration was introduced to destroy the accumulation of the ultrafme powder and to mix the powder with the YBa2 Cu3 07-δ precursor. The melt-process was employed to grow textured samples. From the Scanning Electron Microscope (SEM) graphs, some particles were found in the textured samples, which were about several nanometer in size. The composition of these particles, however, leaves to be identified. The magnetic critical current density (Jcm) at 77K dropped rapidly with the increase of Mg content.
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【期刊论文】Investigation of transverse Peltier effect on top-seeded melt texture Yba2 Cu3 O7-δ
何振辉, Z.H. He, a), Z.G. Ma, Q.Y. Li, Y.Y. Luo, and J.X. Zhang R.L. Meng and C.W. Chu
Appl. Phys. Lett., Vol. 69, No.23, 2 December 1996,-0001,():
-1年11月30日
The transverse Peltier effect is investigated on the top-seeded melt texture superconductor YBa2 Cu3 O7-δ (YBCO). By restricting the heat absorbing or evolving on one of the sample's surfaces, the Peltier heat flow is converted into a temperature difference for measurement. The temperature difference is found proportional to the current applied, which is in accordance with the prediction of transverse Peltier effect. Based on a simplified model, the difference of the Seebeck coefficients between the ab plane and the c axis, uSab2Scu, is about 35mV/K. It is in good agreement with that of large single crystal @I. Terasaki, Y. Sato, S. Tajima, S. Miyamoto, and S. Tanaka, Physica C 235-240, 1413~1994!#. The transverse Peltier effect is verified. This supports the idea that the off-diagonal thermoelectric effect is responsible for the anomalously high laser-induced transient transverse voltage on the oriented YBCO superconducting thin films.
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【期刊论文】Investigation of the Off-Diagonal Thermoelectric Effect on Textured Yba2 Cu3 O7-s
何振辉, Z.H., He, , Z.G. Ma, F.Q. Zhong, Y.Y. Luo, Q.Y. Li, M. Wu, and W. Gavalek
Journal of Superconductivity, Vol.11,-0001,():
-1年11月30日
Both the off-diagonal Seebeck effect and the off-diagonal Peltier effect were investigated on the same textured sample YBa2 Cu3 O7-s, and with the use of the same experimental setup. The effectiveness of several kinds of heat-conductive media was studied for the measurement. The flatness of both the sample and the heat-conducting block, and the matching between them were found very important for the reduction of the heat resistance of the interfaces. A reasonable agreement was found between the off-diagonal Seebeck coefficient measured by the off-diagonal Seebeck effect and that by the off-diagonal Peltier effect. The steplike feature in the relation between the off-diagonal Seebeck coefficient and the annealing temperature may imply a nonmonotonous change of the Seebeck coefficient along the c axis (Sc) with oxygen content.
Thermoelectricity, high-rc texture superconductor, anisotropy, oxygen content
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【期刊论文】FTIR Spectra of the M(EDTA)n− Complexes in the Process of Sol-Gel Technique
何振辉, Y.E. Zhao, , C.Y. Cai, Y.Y. Luo, and Z.H. He, *
Journal of Superconductivity: Incorporating Novel Magnetism, Vol. 17, No.3, June 2004,-0001,():
-1年11月30日
Sol-gel is one of the effective techniques for preparing YBa2Cu3O7−δ (YBCO) coatings at relatively low cost. Its process from gel to oxide coatings, however, was not yet fully understood. This is one of the obstacles for achieving YBCO coatings with good superconducting properties. In this paper, we chose EDTA as the complexant to prepare gels with different kinds of M(EDTA)n−complexes, where M is any combination of Y, Ba, and Cu cations, in order to investigate the decomposition process of the gels with the help of Fourier transform infrared (FTIR) spectra. Comparing the FTIR spectra of the gel powders with those of the calcined powders, we found that the decomposed temperatures were different for different M(EDTA)n−complexes.We considered this was the cause of the Ba segregation (as BaCO3) in the coatings at low heating temperature, which in turn blocked the formation of high quality YBa2Cu3O7−δ.
high temperature superconductor YBa2Cu3O7−δ, EDTA, sol-gel, FTIR spectrum.,
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