Structure and oxygen stoichiometry in Tl2Ba2Ca3Cu4O12−δ a high-resolution powder neutron-diffraction study

✍ Scribed by D.M. Ogborne; M.T. Weller

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 790 KB
• Volume: 223
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)91273-4

✦ Synopsis

The structure of Tl2Ba2Ca3Cu4Ol2_,~ has for the first time been determined by high-resolution powder neutron diffraction and for different oxygen stoichiometries, 6. Results reveal a disordering of the oxygen site in the thallium-oxygen planes, similar to that observed in the other members of the double thallium layer superconductors, and a moderate level of disordering between the thallium and calcium sites. Reduction of the oxygen stoichiometry results in the creation of oxygen vacancies in the thalliumoxide layers, an increase in the apical copper-oxygen bond length and an overall decrease in the c-dimension of the cuprate portion of the structure. The structural changes which occur as a functic~l of the oxygen content are examined in terms of the superconducting transition temperatures of these materials.