La2CuO4 and La1.86Sr0.14CuO4 single crystals were obtained by traveling solvent floating zone method. There were five kinds of defects in these single crystals: cracks, inclusions, gas bubbles, unhomogeneous distribut...La2CuO4 and La1.86Sr0.14CuO4 single crystals were obtained by traveling solvent floating zone method. There were five kinds of defects in these single crystals: cracks, inclusions, gas bubbles, unhomogeneous distribution of Sr2+, and substructures. CH3COOH aqueous solution was used to etch these single crystals, and the etch-pit density was calculated. The fort-nation mechanism of these defects was discussed. It is suggested that the good preparation of raw materials and the stringent growth conditions play an important role in growing high quality single crystals.展开更多
The atomic structure of the perfect AlPdMn icosahedral phase has been studied on a single crystal specimen by quantitative convergent beam electron diffraction (QCBED) technique in combination with describing the shap...The atomic structure of the perfect AlPdMn icosahedral phase has been studied on a single crystal specimen by quantitative convergent beam electron diffraction (QCBED) technique in combination with describing the shape of atomic surface by symmetry\|adapted series of surface harmonics. The spherical model was used as the starting model for the refinement. By fitting the calculated electron diffraction intensities to the experimental line scan profile, the coefficients in the surface harmonics expansion of the boundaries of atomic surface are refined. The refined parameters show that the fluctuations of the external boundary of atomic surface for Pd at n 0 can be as large as 0.2 nm. The boundaries of atomic surfaces for Mn show little fluctuation. In the present model, the number of unphysically short interatomic distances is significantly reduced in comparison with the spherical model.展开更多
YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show tha...YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) substrate.The lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO subetrate.The STO substrate used has mosaic structure.2001 Elsevier Science B.V.All rights reserved.展开更多
文摘La2CuO4 and La1.86Sr0.14CuO4 single crystals were obtained by traveling solvent floating zone method. There were five kinds of defects in these single crystals: cracks, inclusions, gas bubbles, unhomogeneous distribution of Sr2+, and substructures. CH3COOH aqueous solution was used to etch these single crystals, and the etch-pit density was calculated. The fort-nation mechanism of these defects was discussed. It is suggested that the good preparation of raw materials and the stringent growth conditions play an important role in growing high quality single crystals.
基金Supported by the National Natural Science Foundation of China (59871034)
文摘The atomic structure of the perfect AlPdMn icosahedral phase has been studied on a single crystal specimen by quantitative convergent beam electron diffraction (QCBED) technique in combination with describing the shape of atomic surface by symmetry\|adapted series of surface harmonics. The spherical model was used as the starting model for the refinement. By fitting the calculated electron diffraction intensities to the experimental line scan profile, the coefficients in the surface harmonics expansion of the boundaries of atomic surface are refined. The refined parameters show that the fluctuations of the external boundary of atomic surface for Pd at n 0 can be as large as 0.2 nm. The boundaries of atomic surfaces for Mn show little fluctuation. In the present model, the number of unphysically short interatomic distances is significantly reduced in comparison with the spherical model.
文摘YBa2Cu3Ox(YBCO) thin films grown on different substrates with and/or without Eu2CuO4(ECO) buffer layer were investigated by X-ray wide angle diffraction,reflection,diffuse scattering and topography.Theresults show that for the yttria stabilized ZrO2(YSZ) substrate,the presence of an ECO buffer layer improves the crystalline quality of the YBCO film,while a negative effect is observed for the SrTiO3(STO) substrate.The lateral correlation length for a sample grown on a YSZ substrate with ECO buffer Layer is much greater than grown on an STO subetrate.The STO substrate used has mosaic structure.2001 Elsevier Science B.V.All rights reserved.
