Texture formation in Bi2Sr2Ca1Cu2Oχ/Ag tapes prepared by partial melt process

Aksenova, T. D.; Bratukhin, P. V.; Shavkin, S. V.; Mel'nikov, V.L.; Antipova, E.V.; Khlebova, N. E.; Shikov, A.K.

doi:10.1016/0921-4534(93)90392-4

“…In the Bi-2223 compound it is difficult to align well the superconducting grains, because of the complex formation mechanism of the Bi-2223 superconductor phase and the unsuccessful approach of melt texturing the material, whereas in the fabrication process of Bi-2212, the sequence of partial melting and subsequent slow solidification (figure 2) is effective in obtaining a highly oriented c-axis grain microstructure. Thus far four mechanisms for texture formation in melt-processed Bi-2212 have been suggested, namely: (a) heterogeneous nucleation on planar interfaces [6], (b) buoyancy effects [7], (c) opportunistic crystal growth [8] and (d) anisotropic grain growth [9].…”

Section: Introductionmentioning

confidence: 99%

“…Aksenova et al [8] proposed the so-called opportunistic grain growth model for texture formation, after studying Bi-2212-Ag tapes prepared by the 'powder-in-tube' method and the partial-melt process. The opportunistic grain growth model or unimpeded grain growth model is based on the following suppositions: (1) high anisotropy of the crystalgrowth rate, (2) quasi-two-dimensional crystallization space (i.e.…”

Section: Introductionmentioning

confidence: 99%

A model for texture development in BSCCO high-T_csuperconductors

Cecchetti

¹

,

Ferreira

²

,

Sande

³

2000

Supercond. Sci. Technol.

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Textured BSCCO superconductors are studied and the various mechanisms for alignment of BSCCO grains addressed. To date, surface energy effects leading to texture development of BSCCO superconductors have been considered only with respect to the free surface of melt-processed Bi-2212 thick films. However, these previous efforts have not included the surface interactions between BSCCO crystals and other solid surfaces present in the BSCCO system. In the present work, a model based on an interfacial energy relation is proposed. In order to verify the model a variety of experiments have been performed. The observation of the microstructure in different BSCCO samples corroborates this model. The following discussion offers a plausible explanation for the various observed phenomena during the partial melt process. During the early stages of solidification, when the peritectic liquid is abundant, BSCCO crystals are rather mobile, facilitating their contact and interaction. As a result, if a crystal has its wide planar c-surface in contact with a foreign surface (e.g. silver substrate, secondary phases, free surface or another BSCCO crystal), it can minimize its surface energy and is likely adhere to that surface. This mechanism, applied to a system with planar constraints, such as a 2212-Ag film, will result in a textured sample, depending on the thickness of the superconducting layer. In a bulk sample however, BSCCO crystals may only minimize their surface energy by adhering to other BSCCO crystals, which will consequently form clusters of locally aligned crystals, i.e. colonies, with no long-range texture. In this fashion, we may also address the role of silver in promoting texture development in BSCCO superconductors.

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“…The second theory is based on oriented growth, and the fact that 2212 grains grow faster in the a-b directions than they do parallel to the c-axis [16], [17]. In this theory, 2212 grains nucleate and grow randomly in the melt, but only those grains that are favorably oriented with respect to the filament axis will be able to grow appreciably.…”

Section: Discussionmentioning

confidence: 98%

The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Nachtrab

¹

,

Wong

²

,

Liu

³

et al. 2009

IEEE Trans. Appl. Supercond.

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In this study, we investigated the effect of filament size on J e for high filament count Bi2212 round wire conductors partial melt processed with T max between 882 and 890 C in pure oxygen. The filament size that produced maximum J e was between 12 and 15 m depending on conductor design and T max . When the filament size was below 12 m the filaments were unstable during partial melt processing leading to a break-up in the structure of the filament array and low J e . This effect is attributed the formation of interconnects between filaments which leads to coarsening driven by a reduction in interfacial surface energy.Index Terms-Bi2212/Ag round wire, high-temperature superconductors, superconducting filaments and wires.

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“…Thus far four mechanisms for texture formation in melt-processed Bi-2212 have been suggested, namely: (a) heterogeneous nucleation on planar interfaces [6], (b) buoyancy effects [7], (c) opportunistic crystal growth [8] and (d) anisotropic grain growth [9].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Errors in the Measurement of Surface Roughness at High Spatial Frequency by Atomic Force Microscopy on a Thin Film

Wang

¹

,

Itoh

²

2012

Jpn. J. Appl. Phys.

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Textured BSCCO superconductors are studied and the various mechanisms for alignment of BSCCO grains addressed. To date, surface energy effects leading to texture development of BSCCO superconductors have been considered only with respect to the free surface of melt-processed Bi-2212 thick films. However, these previous efforts have not included the surface interactions between BSCCO crystals and other solid surfaces present in the BSCCO system. In the present work, a model based on an interfacial energy relation is proposed. In order to verify the model a variety of experiments have been performed. The observation of the microstructure in different BSCCO samples corroborates this model. The following discussion offers a plausible explanation for the various observed phenomena during the partial melt process. During the early stages of solidification, when the peritectic liquid is abundant, BSCCO crystals are rather mobile, facilitating their contact and interaction. As a result, if a crystal has its wide planar c-surface in contact with a foreign surface (e.g. silver substrate, secondary phases, free surface or another BSCCO crystal), it can minimize its surface energy and is likely adhere to that surface. This mechanism, applied to a system with planar constraints, such as a 2212-Ag film, will result in a textured sample, depending on the thickness of the superconducting layer. In a bulk sample however, BSCCO crystals may only minimize their surface energy by adhering to other BSCCO crystals, which will consequently form clusters of locally aligned crystals, i.e. colonies, with no long-range texture. In this fashion, we may also address the role of silver in promoting texture development in BSCCO superconductors.

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Texture formation in Bi2Sr2Ca1Cu2Oχ/Ag tapes prepared by partial melt process

Cited by 36 publications

References 15 publications

A model for texture development in BSCCO high-T_csuperconductors

A model for texture development in BSCCO high-T_csuperconductors

The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Evaluation of Errors in the Measurement of Surface Roughness at High Spatial Frequency by Atomic Force Microscopy on a Thin Film

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Texture formation in Bi2Sr2Ca1Cu2Oχ/Ag tapes prepared by partial melt process

Cited by 36 publications

References 15 publications

A model for texture development in BSCCO high-Tcsuperconductors

A model for texture development in BSCCO high-Tcsuperconductors

The Effect of Filament Diameter on ${\rm J}_{\rm e}$ in High Filament Count Bi2212/Ag Round Wire

Evaluation of Errors in the Measurement of Surface Roughness at High Spatial Frequency by Atomic Force Microscopy on a Thin Film

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Product

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A model for texture development in BSCCO high-T_csuperconductors

A model for texture development in BSCCO high-T_csuperconductors