Crystal structure and superconductivity in REBaSrCu3Ox

Remarkable influence of heat treatment on the structural and superconducting properties of (Y1–xSmx)(SrBa)Cu3O6+z

“…4 ) and then increases to 84.6 K for x = 1, which was 5 K higher compared to that reported by Wang et al [9]. In the case of YSrBaCu 3 O 6+z , our T c [AO] = 83 K is better than 78 K observed by Wang et al [9] and 81 K reported recently by Awana et al [12]. The evolution of T p with x follows that of T c (see Fig.…”

“…T c was found to be dependent on both x and the heat treatment employed, whereas, T c of the samples [O] decreased from 83 K to 79.3 K as x increased, the [AO] heat treatment increases T c from 81 K to 85 K (see Fig. 4 ) and then increases to 84.6 K for x = 1, which was 5 K higher compared to that reported by Wang et al [9]. In the case of YSrBaCu 3 O 6+z , our T c [AO] = 83 K is better than 78 K observed by Wang et al [9] and 81 K reported recently by Awana et al [12].…”

“…That is, we may obtain LnSrBaCu 3 O 6+z (Ln = all rare earths except Ce, Pr and Tb) as superconductors with T c close to 83 K for z close to 0.9 and expect the orthorhombic symmetry to be retained. Several authors [9 -12] have studied the structural and superconducting properties of LnSrBaCu 3 O 6+z and found that both the symmetry and T c depended on the ionic size of the rare earth [9,10,12]. However, we came across a few contradictory results.…”

“…However, we came across a few contradictory results. In the case of SmSrBaCu 3 O 7 Wang et al [9] reported a tetragonal structure with a = 3.851 Å, c = 11.59 Å and T c = 80 K; whereas Badri et al [10] observed a = 3.859 Å, c = 11.60 Å and T c = 37 K. In both cases, the samples were annealed in oxygen at 450 °C for more than 48 h. Further, no magnetic measurements were reported. Recently, Awana et al [12] reported T c = 81 K in an orthorhombic YSrBaCu 3 O 7 without indicating lattice parameters, whereas Wang et al [9] reported T c = 78 K in this case.…”

Specific Heat of RBa2Cu3O7-xand RBaSrCu3O7-xCompounds (R = Sm, Dy, Er)

“…They allow for further refinement of CEF parameters obtained from INS studies [7,8]. The Sr-substituted compounds RBaSrCu 3 O7-x are known to belong to R123O7-x family with T^ between 54 and 86 K [9]. With the Sr substitution, the compounds in which ionic radius of R3+ r R < rDy, preserve orthorhombic while those with rR > rDy have the tetragonal structure.…”