Title :
The synthesis of new phases related to YBCO by complete replacement of the chain copper sites
Author :
Greaves, C. ; Slater, P.R.
Author_Institution :
Sch. of Chem., Birmingham Univ., UK
fDate :
3/1/1991 12:00:00 AM
Abstract :
The extent to which new phases may be synthesized by the replacement of the chain Cu sites (Cu1) in the YBa2Cu3 O7 structure was examined. Several new phases have been prepared, and it is demonstrated that, for cations which preferentially substitute at this site, it becomes possible to prepare phases in which the Ba cations have been totally replaced by Sr, e.g. EuSr2Cu 2NbO8. All phases of this type are tetragonal, and, using Rietveld refinement techniques and powder X-ray diffraction data, it has been confirmed that the Nb occupies only the Cu1 position and adopts octahedral coordination in EuSr2Cu2NbO 8. Phases involving other substituting cations are also discussed. Superconductivity has not been observed in these phases
Keywords :
barium compounds; crystal atomic structure of inorganic compounds; europium compounds; high-temperature superconductors; materials preparation; phase equilibrium; strontium compounds; yttrium compounds; Cu1 position; EuSr2Cu2NbO8; Rietveld refinement techniques; YBCO; YBa2Cu3O7; chain Cu sites; chain copper sites; high temperature superconductors; new phases; octahedral coordination; powder X-ray diffraction; substituting cations; synthesis; tetragonal; Chemistry; Crystallography; Neodymium; Niobium; Powders; Stability; Strontium; Superconductivity; X-ray diffraction; Yttrium barium copper oxide;
Journal_Title :
Magnetics, IEEE Transactions on
