Substitution effects on the ruthenium, strontium and gadolinium sites in the RuSr 2 GdCu 2 O 8 compound
- PDF / 1,359,436 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 68 Downloads / 158 Views
FF6.22.1
Substitution effects on the ruthenium, strontium and gadolinium sites in the RuSr2GdCu2O8 compound. E. Chavira1*, M. Abatal1, C. Filippini2, J. L. Tholence2, V. García-Vázquez3, J. C. Pérez3, A. Sulpice4 and Henri Noël5. 1 IIM-UNAM, AP 70-360, 04510 MEXICO, 2 LEPES-CNRS, 25, Av. Des Martyrs B. P. 166 38042 Grenoble, FRANCE, 3 IF-LRT, BUAP, AP J-48,72570 Puebla, MEXICO, 4 CRTBT-CNRS, 25, Av. Des Martyrs B. P. 166 38042 Grenoble, FRANCE, 5 LCSIM-CNRS, Av. du Général Leclere, 35042 Rennes, FRANCE. ABSTRACT We present the more relevant results of various cationic substitutions in the RuSr2GdCu2O8 (Ru-1:2:1:2) compound. The substitutions were synthesized by solid-state reaction at ambient pressure in the following systems: Ru1-xSr2GdCu2+x O8 (0.0 < x < 1.0), Ru(Sr2-xCax)GdCu2O8 (0 < x < 2.0) and RuSr2(Gd1-xLnx)Cu2O8 (0 < x < 0.9) with Ln = Dy, Ho, Er, Yb and Lu. All of them were isostructural to Ru-1:2:1:2 compound with tetragonal unit cells. The phases have been characterized by X-Ray powder Diffraction (XRD), observing a solid solution (ss) up to x = 0.4 for Ru ions replaced by Cu ions, x = 0.1 when we substitute Sr atoms by Ca atoms, and x = 0.7 changing Gd ions by Ln ions. As a result of the Scanning Electron Microscopy (SEM), the grain sizes were discovered to be 1 – 10 µm. The Energy Dispersive X-ray spectroscopy (EDX) analysis permitted us to analyze the impurities that we did not detect with XRD. We observed semiconducting, isolated and ferromagnetic behaviors. No superconducting transition could be observed for these ambient preparation conditions. 1. INTRODUCTION The rutheno-cuprates were synthesized for the first time by Bauernfeind et al. [1, 2]. This study reports that their transport properties are only high-Tc compounds, but magnetic measurements were not done until recently [3]. The RuSr2RCu2O8 (R: rare earth) system with tetragonal unit cell can be derived from the YBa2Cu3O7 compound, where Cu-O chains are completely replaced by RuO2 layers; R and Sr substitute Y and Ba respectively. The Ru1xSr2GdCu2+xO8 system allows the study of superconductivity and magnetism phenomena by modifying the Cu-O and Ru-O planes responsible for each phenomenon. Klamut et al. [4] reported the synthesis of the Ru1-xSr2GdCu2+xO8 system at high-pressure oxygen atmosphere and investigated the effects of replacing Ru with Cu (0.0 ≤ x ≤ 0.75). They found it was possible to raise Tc to 72 K. Yang et al. [5] present the synthesis by solid state reaction at ambient pressure of Ru(Sr2-xBax)GdCu2O8 system and they found that the substitution of Ba atoms on the Sr site increase the Tc from 16 K at x = 0.0 to 35 K for x = 0.07 composition, without variation in the ferromagnetic transition temperature (TCurie = 136 K). In order to extend the knowledge of the Ru-1:2:1:2 family, Ruiz-Bustos et al. [6] have succeeded in replacing Gd by Tb, Dy, Y, and Er by high-pressure method. In this paper we report the synthesis by solid state reaction of previous systems, without applying a high-oxygen pressure or high-pressure. We discuss the
Data Loading...
