Title :
Rapid solidification of high-Tc oxide superconductors by a laser zone melting method
Author :
Nagaya, S. ; Miyajima, M. ; Hirabayashi, I. ; Shiohara, Y. ; Tanaka, S.
Author_Institution :
Supercond. Res. Lab., ISTEC, Nagoya, Japan
fDate :
3/1/1991 12:00:00 AM
Abstract :
The direct crystallization of the YBa2Cu3O 7 orthorhombic superconducting phase from the solution of the 123 composition has been realized by a rapid solidification using a laser zone melting method. This method is characterized by two processing parameters: the temperature gradient (G) and the growth rate (R). Under the higher G and R conditions, the nonequilibrium phase transformation occurred, and the direct crystallization of the orthorhombic phase from the melt of the 123 composition was realized. An as-grown solidification sample exhibited superconducting phase transition at 94 K, according to a magnetization measurement. The structure in which Y2O3 fine particles dispersed homogeneously was obtained in the lower R region. It is possible to use this structure as a long and narrow precursor for the melt process. By annealing at 1000°C, the critical current density of the sample was 1.5×104 A/cm2 at 77 K, 0 T, according to a magnetization measurement
Keywords :
barium compounds; critical current density (superconductivity); high-temperature superconductors; laser beam effects; rapid solidification; superconducting transition temperature; yttrium compounds; zone melting; 123 composition; 94 K; YBa2Cu3O7; critical current density; direct crystallization; growth rate; high temperature superconductor; laser zone melting method; magnetization measurement; nonequilibrium phase transformation; rapid solidification; superconducting phase transition; temperature gradient; Critical current density; Crystalline materials; Crystallization; Grain boundaries; Laboratories; Magnetization; Solid lasers; Superconducting materials; Superconductivity; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
