Growth and structural characterization of needlelike metastable crystals in the Nd-Ba-Cu-(Al)-O system

M. Scavini, Paolo Mele, G. A. Costa, M. Ferretti

Research output: Contribution to journalArticle

Abstract

An unconventional technique was used to grow crystals in the Nd-Ba-Cu-O system. A Nd4Ba2-Cu2O10 (Nd-422) bar was supported on two NdBa2Cu3Ox (Nd-123) pellets in an alumina crucible and was heated in a horizontal furnace at a higher temperature than the peritectic decomposition point of Nd-422. Brown Al-doped Nd-Ba-Cu-O needlelike crystals belonging to a new phase were grown directly on the crucible. The structure of the new phase, whose composition is Nd6Ba9.78Sr0.22Cu2Al 6O30, has been determined by single-crystal X-ray diffraction. The space group is P63mc; the unit cell parameters are a = 11.526(2) Å, c = 6.963(1) Å, and Z = 1. A full matrix least-squares refinement yielded R(F) = 0.0405 for 3131 independent reflections. This new phase is a metastable polymorphic modification of Nd-422 solid solution. The preferential directional growth of the needles lies along the c-axis. Many needles are affected by twinning by merohedry, with the twinning plane parallel to the (001) crystallographic plane.

Original languageEnglish
Pages (from-to)1259-1263
Number of pages5
JournalCrystal Growth and Design
Volume4
Issue number6
DOIs
Publication statusPublished - 2004 Nov 1
Externally publishedYes

Fingerprint

Twinning
Crucibles
crucibles
twinning
needles
Needles
Crystals
Aluminum Oxide
Phase composition
pellets
crystals
furnaces
Solid solutions
Furnaces
solid solutions
Alumina
aluminum oxides
Single crystals
Decomposition
decomposition

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Growth and structural characterization of needlelike metastable crystals in the Nd-Ba-Cu-(Al)-O system. / Scavini, M.; Mele, Paolo; Costa, G. A.; Ferretti, M.

In: Crystal Growth and Design, Vol. 4, No. 6, 01.11.2004, p. 1259-1263.

Research output: Contribution to journalArticle

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