A system formed by a bar of Y2BaCuO5 (Y211) phase supported on two YBa2Cu3Ox (Y123) pellets was processed by thermal treatment at high temperature. The first effect was a change in chemical composition inside the bar, yielding new phases: mostly Y123 and BaCuO2. Their concentrations were higher near the bar ends. A second, very interesting result was the growth of two kinds of acicular crystals underneath the whole bar: green, transparent Y211 needles and needles with a green core of Y211, covered by a Y123 layer. Micro Raman and SEM analyses clearly identified the two different phases. XRD inspection has confirmed that Y211 crystals are high-quality single crystals. The preferential growth direction for Y211 needles is along the crystallographic b axis. A possible explanation, based on the VLS mechanism, for their growth is suggested.

Growth and structural characterization of needlelike crystals in the Y-Ba-Cu-O system / P. Mele, A. Ubaldini, M. M. Carnasciali, G. A. Costa, M. Scavini. - In: CRYSTAL GROWTH & DESIGN. - ISSN 1528-7483. - 6:8(2006), pp. 1761-1765.

Growth and structural characterization of needlelike crystals in the Y-Ba-Cu-O system

M. Scavini
Ultimo
2006

Abstract

A system formed by a bar of Y2BaCuO5 (Y211) phase supported on two YBa2Cu3Ox (Y123) pellets was processed by thermal treatment at high temperature. The first effect was a change in chemical composition inside the bar, yielding new phases: mostly Y123 and BaCuO2. Their concentrations were higher near the bar ends. A second, very interesting result was the growth of two kinds of acicular crystals underneath the whole bar: green, transparent Y211 needles and needles with a green core of Y211, covered by a Y123 layer. Micro Raman and SEM analyses clearly identified the two different phases. XRD inspection has confirmed that Y211 crystals are high-quality single crystals. The preferential growth direction for Y211 needles is along the crystallographic b axis. A possible explanation, based on the VLS mechanism, for their growth is suggested.
Settore CHIM/02 - Chimica Fisica
2006
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/32214
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