Comparative study of MSr2RECu2O7+δ compounds with M = Al, Nb, Fe, Ru, Ga and Co and RE = Eu, Y

Comparative study on various systems originated from MSr2RECu2Oz (M-1212; 0 ≤ δ < 1) compounds (M = Al, Nb, Fe, Ru, Ga and Co and RE = Eu, Y) has been made. The Rietveld refinement is done for all samples on their respective X-ray diffraction (XRD) patterns, which showed that all compounds are crystallized in single phase. While, Nb-, Fe-, Ru- and Al-1212 possess tetragonal P4/mmm space group structure, the Ga-1212 and Co-1212 are crystallized in orthorhombic Ima2 space group. The change of space group from P4/mmm to Ima2 resulted in doubling of unit cell. The buckling angle [Cu2–O2–Cu2 angle] determined, showed that most of the studied samples are under doped and hence they lack superconductivity. Thermogravimetric analysis (TGA) showed the M-1212 compounds to be more stable than widely studied 90 K superconductor Cu-1212 (RE-123). The magnetization behavior of Ga-, Nb- and Al-1212 follows a Curie–Weiss like behavior due to paramagnetic contribution of Cu. In case of Co-, Fe-1212 short magnetic correlations/spin-glass like features is seen below 100 K. Different surface morphologies have been observed from the scanning electron microscopy (SEM) study of all the samples. Efforts are underway to dope mobile carriers in studied single phase under doped M-1212 (M = Ga, Nb, Fe, Al and Co) compounds and to introduce superconductivity in them.