Electron microscope studies of structural characteristics of Tl(Bi)-Sr-Ca-Cu-O high temperature superconductor
Year: 1991
Type: article
Abstract: Tl(Bi)-Sr-Ca-Cu-O corresponding to nominal compositions Tl:Bi:Sr:Ca:Cu=(2-x):x:2:2:3 (where x=0.2, 0.4, 0.6 and 1) and T c ranging between approximately 77 K and approximately 106 K have been synthesized and their structural characteristic explored employing the technique of transmission electron microscopy. An interesting result arising from structural explorations in the present investigation is the presence of a new disordered superstructure a approximately=4.2 AA, c approximately=15.26 AA) embedded in the main monolayer Tl-0, 1212/1223-type structural matrix. Although the new disordered superstructural phase is present for all the compositions studied, its density was found to be highest for the nominal composition Tl 1.6 Bi 0.4 Sr 2 Ca 2 Cu 3 O 10 . This also corresponds to the highest T c approximately 106 K HTS (high-temperature superconductor) material. It has been suggested that the substitution of Bi for Tl produces disorder through the occurrence of a lone pair on Bi 3+ . Besides the creation of disorder, the presence of Bi 3+ may also lead to the optimization of carrier concentration and hence T c .
Authors: G D Verma, K Ramakrishna, O N Srivastava
Institution: Banaras Hindu University
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2010552307