Oxygen stoichiometry and structural parameters of Sm1+xBa2-xCu3Oy solid solutions versus composition and temperature

The effects of temperature and samarium content on oxygen stoichiometry and crystal lattice parameters of the Sm(1+x)Ba(2-x)Cu(3)O(y) solid solutions (Sm123ss) prepared by the citrate sol-gel method were studied. It was found that there are three compositional ranges of variation of the structural-chemical characteristics of the Sm123ss corresponding to the regions of existence of the following three phases: orthorhombic phase I (0 < x < 0.15-0.20), tetragonal phase (0.20 < x < 0.60) and orthorhombic phase II (x > 0.65). The above phases behave differently with temperature: (a) the orthorhombic phase I behaves with temperature like the Y123 phase; (b) the lattice parameters a and c of the tetragonal phase vary, i.e., its lattice is relatively rigid as oxygen is removed; (c) the orthorhombic phase 11 has a very rigid crystal lattice. (C) 2004 Elsevier B.V. All rights reserved.