Title :
New Tl-Ba-Ca-Cu-O (1234 and 1245) superconductors with Tc>117 K
Author :
Ihara, H. ; Hirabayashi, Miki ; Terada, N. ; Jo, Minho ; Hayashi, K. ; Tokumoto, Mitsuhiro ; Kimura, Yuichi ; Shimomura, Takaaki ; Ohashi, Satoru
Author_Institution :
Electrotech. Lab., Ibaraki
fDate :
3/1/1989 12:00:00 AM
Abstract :
TlBa2Ca3Cu4O11 (1234) and TlBa2Ca4Cu5O13 (1245) superconductors have been synthesized for the first time. The compounds have Tc values of 116~122 K. The highest T c value was obtained for the 1234 phase. These are single Tl-O layer compounds with less than half the Tl content of the previous 2223 phase. The structure of the compounds is a simple tetragonal phase with the lattice constants of a=b=3.85 Å and c=19.1 Å for the 1234 phase and a=b=3.85 Å and c=22.3 Å for the 1245 phase. The electron diffraction patterns and the lattice images from a high-resolution TEM have confirmed an oxygen-deficient layered-perovskite structure with the P4/mmm space group. The c-lattice constant follows the c-axis rule of a linear relation of c=6.3+3.2 n (n=the number of Cu-O layers), The Tc value is strongly related to the valence of Cu ion
Keywords :
barium compounds; calcium compounds; crystal atomic structure of inorganic compounds; electron diffraction examination of materials; high-temperature superconductors; lattice constants; space groups; superconducting transition temperature; thallium compounds; transmission electron microscope examination of materials; 116 to 122 K; Cu ion valence; P4/mmm space group; TlBa2Ca3Cu4O11; TlBa2Ca4Cu5O13; c-axis rule; electron diffraction patterns; high temperature superconductivity; high-resolution TEM; lattice constants; lattice images; layered-perovskite structure; simple tetragonal phase; single Tl-O layer compounds; transition temperature; Electrical resistance measurement; Electrons; Furnaces; Plasma measurements; Plasma temperature; Powders; Probes; Superconductivity; Temperature measurement; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
