Title :
Initial crystallization and growth in melt processing of large-domain YBa/sub 2/Cu/sub 3/O/sub x/ for magnetic levitation
Author :
Donglu Shi ; Zhong, W. ; Dorris, S.E. ; Balachandran, V. ; Welp, U. ; Sengupta, S. ; Todt, V.R. ; Crabtree, G.W.
Author_Institution :
Dept. of Mater. Sci. & Eng., Cincinnati Univ., OH, USA
fDate :
6/1/1995 12:00:00 AM
Abstract :
The crystallization temperature in YBa/sub 2/Cu/sub 3/O/sub x/ (123) during peritectic reaction has been studied by differential thermal analysis and optical microscopy. It has been found that 123 experiences partial melting near 1010/spl deg/C during heating, and that crystallization takes place at a much lower temperature upon cooling, indicating a delayed nucleation process. A series of experiments has been conducted to search for the initial crystallization temperature in the YBa/sub 2/Cu/sub 3/O/sub x/+ liquid phase field. We have found that for slow cooling (1/spl deg/C/h), grain texturing for 123 can start as low as 960/spl deg/C. Low-temperature processing has resulted in high-quality, large-domain, strongly pinned 123 specimens.<>
Keywords :
barium compounds; cooling; crystal growth from melt; heat treatment; high-temperature superconductors; magnetic levitation; optical microscopy; thermal analysis; yttrium compounds; 1010 C; 960 C; YBa/sub 2/Cu/sub 3/O/sub 7/; YBa/sub 2/Cu/sub 3/O/sub x/; cooling; crystallization temperature; delayed nucleation; differential thermal analysis; grain texturing; heating; large-domain strongly pinned specimen; magnetic levitation; melt processing; optical microscopy; peritectic reaction; Cooling; Crystallization; Heating; Magnetic levitation; Materials science and technology; Melt processing; Powders; Power engineering and energy; Temperature distribution; US Department of Energy;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
