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2005年10月19日

【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

摘要

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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2005年10月19日

【期刊论文】Y Ba Sn3--z Cu Pt/O in textured YBCO superconductors

何振辉, Z.H. He a, b, ), , M.Z. Wu b, G. Bruchlos b, X.M. Xiong a, Y.Y. Luo a, W. Gawalek b

Z.H. He et al.rPhysica C 312 (1999) 261-268,-0001,():

-1年11月30日

摘要

Ultrafine SnO2 powder was made with grain size down to 20 nm. Such powder was introduced into the textured growth of Y1qx Ba2 Cu3 O7qd YBCO.superconductors. Crystalline inclusions, which were cubic in shape and from micrometer to submicrometer in size, were found trapped inside such grown YBCO superconductors. Determined by energy dispersive spectroscopy EDS., and further confirmed by X-ray diffraction, the composition of the inclusions was Y2Ba5 Sn3 yyyz Cuy Ptz.Ox. This Sn-based phase belongs to double perovskite structures. They were not trapped uniformly inside the YBa2Cu3O7yd 123., possibly caused by the agglomeration of the SnO2 powder at the very beginning. Nevertheless, it is possible for fine Sn-based inclusions down to a few hundred nanometers to be trapped inside the 123. The addition of the ultrafine SnO2 to YBCO textured superconductors without Pt did not seem to affect the size of Y2Ba Cu O5 211.particles. For comparison, Y2Sn2O7was also introduced to YBCO textured superconductor. In this case, the so-called f phase YBa3 Sn2 yx Cux O9yd was found. q1999 Elsevier Science B.V. All rights reserved.

Ultrafine SnO2, YBCO, Y2Ba5 Sn3 yyyz Cuy Ptz., Ox, Double perovskite, Textured high Tc superconductors

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2005年10月19日

【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

摘要

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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2005年10月19日

【期刊论文】Investigation of microstructure of textured YBCO with addition of nanopowder SnO2

何振辉, Z.H. He a, ., T. Habisreuther b, G. Bruchlos b, D. Litzkendorf b, W. Gawalek b

Z.H. He et al./Physica C356 (2001) 277-284,-0001,():

-1年11月30日

摘要

Received 10 November 2000; received in revised form 24 January 2001; accepted 27 February 2001 By using top seeding melt-textured growth (TSMTG) process, large single domain YBaz Cu3 07 JY2 Ba Cu O5 (YBCO) samples were prepared with addition of nanometric SnO2 and normal CeOy. Polarized light microscope studies at each step of the TSMTG process showed that before YBa2 Cu3 07 δ (123) melting, the Sn-based reacted products were uniformly distributed in micrometer scale; after solidification, the trapped YyBaCuO5 (211) and Sn-based inclusions were more homogeneously distributed and with mean sizes of about one micrometer. Composition images of scanning electronic microscope for the textured samples showed that, on the whole, the Sn-based inclusions were smaller than the 211. They must be on average below one micrometer in size. Although evidence was found that very fine Sn-based inclusions were uniformly trapped in 123 matrix, the fraction of them was small in comparison to that of 211. No significant enhancement of superconducting critical current density (Jc) was evidenced for the nanometric SnOy-doped samples at a low magnetic field (B<1 T). However, values of Jc were decreased at intermediate magnetic field (1<B<3 T). 2001 Elsevier Science B.V. All rights reserved.

Ultra-fine SnOy, Defects, Textured high Tc superconductors

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2005年10月19日

【期刊论文】Microstructure and superconductivity of the melt-textured YBCO grown with the addition of SnO2

何振辉, Z.H. He, , O.B. Surzhenko, T. Habisreuther, M. Zeisberger, D. Litzkendorf, and W. Gawalek

Physica C 341-348 (2000) 1987-1988,-0001,():

-1年11月30日

摘要

Large domain YBa2 Cu3 07-δ/2BaCuO5 (YBCO) samples were prepared by top-seeded melt-textured process, with the addition of SnO2 and CeO2 or PtO2. It was found that, in comparison to that in the CeO2-doped sample, the YBa2 Cu3 O7-δ(123) matrix was twisted in the PtO2-doped sample and its Y2BaCuO5 (211) particles were larger on average and less homogeneously distributed. The PtO2-doped sample showed a more obvious second-peak effect, and higher values of a-b plane critical current density (3Jcab) and irreversibility fields (Bt,,). The enhancement of3 Jcab is related to the microstructure inhomogeneity and the core surface AK pinning.

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    中山大学,广东

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