Title :
Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub /spl delta// thin films on MgO annealed in a sealed capsule
Author :
Nemoto, M. ; Yoshikawa, S. ; Shimaoka, K. ; Niki, K. ; Yoshida, I. ; Yoshisato, Y.
Author_Institution :
Tsukuba Res. Centre, Sanyo Electr. Co. Ltd., Ibaraki, Japan
fDate :
6/1/1997 12:00:00 AM
Abstract :
High-quality c-axis oriented Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub /spl delta// thin films have been prepared on MgO, which is more suitable for high frequency applications than LaAlO/sub 3/ because of its lower dielectric constant (/spl epsi/) and smaller dielectric loss tangent (tan /spl delta/). Annealing of the thin films was carried out in an alumina capsule sealed with a gold gasket. It was revealed that preannealing of the pellets for Tl compensation is effective in improving the structural properties of the thin films. X-ray diffraction (XRD) rocking curve scans of Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub /spl delta// (0 0 12) reflection revealed that a full width of half maximum (FWHM) of thin films annealed with an unpreannealed pellet is 0.89/spl deg/, while that of thin films annealed with a preannealed pellet is 0.22/spl deg/. The highest critical temperature (T/sub c/) is 108 K and the highest critical current density J/sub c/ is 2/spl times/10/sup 6/ A/cm/sup 2/ at 77 K.
Keywords :
X-ray diffraction; annealing; barium compounds; calcium compounds; critical current density (superconductivity); high-temperature superconductors; scanning electron microscopy; sputtered coatings; superconducting thin films; superconducting transition temperature; surface structure; thallium compounds; 108 K; 77 K; Al/sub 2/O/sub 3/ capsule; Au gasket; MgO; MgO substrate; RF magnetron sputtering; SEM; Tl compensation; Tl/sub 2/Ba/sub 2/CaCu/sub 2/O; Tl/sub 2/Ba/sub 2/CaCu/sub 2/O/sub /spl delta// thin films; X-ray diffraction rocking curve scans; annealing; critical current density; critical temperature; dielectric constant; dielectric loss tangent; high frequency applications; high-quality c-axis oriented films; pellet preannealing; sealed capsule; structural properties; surface morphology; Annealing; Dielectric constant; Dielectric losses; Dielectric thin films; Frequency; Gaskets; Gold; Transistors; X-ray diffraction; X-ray scattering;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
