Structure and morphology of NdSr2RuCu2Oy and GdSr2RuCu2Oz

The structural and morphological properties of the NdSr2RuCu2Oy (Nd1212) compound, which has been recently synthesized as a pure perovskite phase, are reported and compared with the properties of the magnetic superconducting triple perovskite GdSr2RuCu2O8 (Gd1212). The preparation of the RESr2RuCu2O8 (RE1212, RE = Rare Earth) phases is also critically reviewed and the nature of the magnetic ordering of these materials has been investigated and correlated to the structural properties. The crystal structure of RE1212 compounds have been determined by a combined study of high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and high-resolution X-ray powder diffraction (HRXRPD) using synchrotron radiation. These measurements show that Nd1212 has a symmetric cubic structure with a high degree of disorder between cation sites in contrast with the well ordered tetragonal structure of Gd1212. The cation intermixing avoids the formation of extended CuO2 and RuO2 planes, responsible for the superconducting and magnetic properties. Thus, Nd1212 does not show any superconductivity and/or magnetic ordering, while Gd1212 shows the coexistence of superconductivity and ferromagnetism. To have a better insight into the formation of RE1212 phases, temperature XRPD measurements have been performed. The morphology of the sample has been monitored by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) attachment by which the microanalysis of the crystallites has been also performed.