Abstracts Book - IMRC 2018

• SF1-O002 Invited Talk
COPPER BY MOLIBDENIUM AND IRON SUBSTITUTIONS IN YBCO
REVISITED
Miguel Angel Alario Franco 1 , Sara López Paz 1 , Xabier Martínez de Irujo 1 , Irene Herrero
Ansorregui 1 , Emilio Morán 1 , Susana Garcia Martín 1
1 Universidad Complutense de Madrid, Química Inorgánica-I, Spain.
Since the discovery of high temperature superconductivity in oxides of the La2-
xBaxCuO4-δ family by Bednorz and Muller in 1986 [1], reporting a critical
temperature (Tc) of ~30 K, attempts to increase the Tc in cuprates rapidly
attracted the focus of the field. From the Solid State Chemistry point of view,
substitutions of the copper in the chains- also called the Charge Reservoir
Layer_, preventing the simultaneous replacemnt of the copper in the SC planes,
has been, indeed still is, one of the favourite procedures to modify, and
eventually improving the SC properties, in particular Tc. The M-1212 family of
cuprates, of general formula MxCu1-xSr2RECu2O7-δ (M= transition metal; RE=
Rare Earth), can be stabilized at room pressure [2] and continues to be the basis
for the study of superconducting cuprates by means of different total or partial
substitutions. Here, we explore two interesting possibilities through substitution
of Cu in the chains by Mo and Fe, leading to the FexCu1-xSr2YCu2O7-δ (x=0.5, 1)
and Mo0.3Cu0.7Sr2RECu2O7-δ (RE: Pr, Nd, Gd, Tm and Yb) systems respectively.
Innovative oxidation techniques such as electrochemical treatment, ozonization
and high-pressure-oxygen treatment have been used in order to increase the
TC of the present compounds. In the case of the partial substitution of Ru by a
Cu/Mo mix, widely studied last years in our research group [3,4], we have
replaced a number of Rare Earths and studied the influence of the mixing of the
A cations on Tc, depending on the RE size. In the last considered case, we have
replaced Cu by Fe (1:1 or 0.5:0.5) observing that both Tc and the
superconducting fraction vary substantially after the different oxidizing
treatments. [1] Bednorz, J.G., Muller, K.A., Z Phys B. 64. 189 (1986) [2] T. Den, T.
Kobayashi. Physica C, 1992, 196, 141. [3] S. Marik, C. Labrugere, O. Toulemonde,
E. Morán, M. A. Alario-Franco. Dalton Trans, 2015, 44, 10795. [4] S.Marik, A.J. Dos
Santos-Garcia, E. Morán, O. Toulemonde, M.A. Alario-Franco, MR Advances,
2016, 1(17), 1215
Acknowledgment: