Title :
Microstructure and properties of Bi-Sr-Ca-Cu-O with additions of nanometer-scale alumina
Author :
Goretta, K.C. ; Cuber, M.M. ; Feng, L.R. ; Fisher, B.L. ; Jiang, M. ; Lanagan, M.T. ; Balachandran, U. ; Xu, Y. ; Xu, M.
Author_Institution :
Argonne Nat. Lab., IL, USA
fDate :
6/1/1999 12:00:00 AM
Abstract :
Al/sub 2/O/sub 3/ particles /spl ap/30 nm in size were added to Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ in a 1:4 molar ratio. For comparison, 0.3- and /spl ap/3-/spl mu/m Al/sub 2/O/sub 3/ particles were added to separate batches. All of the materials were partial-melt processed. The Al/sub 2/O/sub 3/ reacted during melting to form stable compounds, primarily of approximate composition (Sr,Ca)/sub 2/AlO/sub 4/. All additions caused slight decreases in the T/sub c/ and melting point of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/. The submicrometer Al/sub 2/O/sub 3/ additions induced large expansions in magnetic-hysteresis width at 6 K. Electron microscopy examination strongly suggested that the hysteresis expansion was related to alloying of the Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ matrix rather than to pinning by volume defects.
Keywords :
alumina; bismuth compounds; calcium compounds; crystal microstructure; electron microscopy; high-temperature superconductors; magnetic hysteresis; melting point; strontium compounds; superconducting transition temperature; Al/sub 2/O/sub 3/ particles; Bi-Sr-Ca-Cu-O; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/; BiSrCaCuO-Al/sub 2/O/sub 3/; HTSC; alloying; electron microscopy; magnetic-hysteresis width; melting point; microstructure; nanometer-scale alumina; pinning; transition temperature; volume defects; Heat treatment; Heating; High temperature superconductors; Magnetic hysteresis; Microstructure; Powders; Scanning electron microscopy; Transmission electron microscopy; US Department of Energy; X-ray diffraction;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
