New Tl-Ba-Ca-Cu-O (1234, 1245 and 2234) Superconductors with Very High Tc
New TlBa2Ca3Cu4O11 (1234), TlBa2Ca4Cu5O13 (1245) and Tl2Ba2Ca3Cu4O12 (2234) superconductors with Cu-O multilayers above four layers have been synthesized. These compounds have Tc values of 117, 122 and 115 K, respectively. The 1234 phase showed the highest Tc value in the TlBa2Can-1CunO2n+3 superconductor family. The Tc value of 2234 phase was lower than that of 2223 phase.
The single Tl-O layered compounds have a simple tetragonal phase of the space group of P4/mmm 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 double Tl-O layered 2234 phase has a body-centered-tetragonal structure with the lattice constants of a = b = 3.85 Å and c = 42.0 Å. Electron diffraction patterns and lattice images from a high resolution TEM have confirmed that these compounds have an oxygen-deficient layered-perovskite structure. Their c-lattice constants follow the c-axis rule of linear relations of c = 6.3 +3.2 n Å (n = the multiplicity of CuO layers in aunit) in the single T1-0 layer compound family and c=2 (8.2 + 3.2 n) Å in the double T1-0 layer compound family.
KeywordsLattice Constant Electron Diffraction Pattern Layer Compound Lattice Image Experimental Lattice Constant
Unable to display preview. Download preview PDF.
- H. Ihara, M. Hirabayashi, N. Terada, M. Jo, K. Hayasi, A. Negishi, M. Tokumoto, H. Oyanagi, R. Sugise, T. Shimomura and S. Ohasi, Proc. MRS Intern. Meeting on Advanced Materials (May 1988, Tokyo); IEEE Magn. MAG25 No.3 (1989).Google Scholar
- H. Ihara, M. Hirabayashi, R. Sugise, N. Terada, M. Jo, K. Hayashi, M. Tokumoto, T. Shimomura and S. Ohashi, (in print Phys. Rev. B 38 No16 (1988)).Google Scholar