Recrystallization of amorphous and nanocrystalline NdBa/sub 2/Cu/sub 3/O/sub 7-x/ and GdBa/sub 2/Cu/sub 3/O/sub 7-x/

Author

Folkerts, T.J. ; Dennis, K.W. ; Yoo, S.I. ; Xu, Y. ; Kramer, Matt J. ; McCallum, R.W.

Author_Institution

Iowa State Univ., Ames, IA, USA

Volume

3

Issue

1

fYear

1993

fDate

3/1/1993 12:00:00 AM

Firstpage

1150

Lastpage

1153

Abstract

Using a novel melt-spinning technique, the authors have produced both amorphous and nanocrystalline NdBa/sub 2/Cu/sub 3/O/sub 7-x/ and GdBa/sub 2/Cu/sub 3/O/sub 7-x/ materials. Samples melt-spun in O/sub 2/ consist of nanocrystals with the tetragonal 123 structure while those processed in N/sub 2/ show an amorphous matrix with small amounts of crystalline BaCu/sub 2/O/sub 2/, as shown by X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. The difference is due to the strong dependence of the phase relations on the O/sub 2/ partial pressure. Superconductivity can be fully restored by heating above 1000 degrees C followed by a 450 degrees C anneal in O/sub 2/. High-temperature XRD studies show that the 123 phase crystallizes directly from the amorphous matrix below 800 degrees C. Restoration of the orthorhombic 123 phase does not necessarily ensure good superconducting properties, a result attributed to disorder on the heavy metal sites.<>

Keywords

X-ray diffraction examination of materials; amorphous state; barium compounds; ceramics; gadolinium compounds; high-temperature superconductors; melt spinning; nanostructured materials; neodymium compounds; transmission electron microscope examination of materials; 123 phase; GdBa/sub 2/Cu/sub 3/O/sub 7-x/; HTSC; N/sub 2/; NdBa/sub 2/Cu/sub 3/O/sub 7-x/; O/sub 2/; TEM; X-ray diffraction; XRD; amorphous matrix; nanocrystals; novel melt-spinning technique; tetragonal 123 structure; transmission electron microscopy; Amorphous materials; Annealing; Crystalline materials; Crystallization; Heating; Nanocrystals; Superconductivity; Transmission electron microscopy; X-ray diffraction; X-ray scattering;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.233350

Filename

233350