High-pressure Synthesis and Physical Characterization of Y-based 1222-type Niobio–Cuprate NbSr(YCe)CuO

We have successfully synthesized a new 1222-type Y-based niobio-cuprate for the first time with the chemical composition, NbSr(YCe)CuO by a high-pressure and high-temperature (HPHT) technique under different synthesis conditions. Good quality (nearly single-phase) Nb1222Y polycrystalline sample was synthesized at 1,450C and 6 GPa for 2 h. It crystallizes in a tetragonal symmetry of space group I4/ with lattice parameters ==3.863(2) Å and =28.687(5) Å, which is isostructural with the corresponding Ru1222Y (RuSr(YCe)CuO) phase. The -magnetic susceptibility measurements ∼29. The magnetic moment () versus field () curve of Nb1222Y sample measured at 1.8 K looks like a hybrid and it normally ensembles for both superconducting and a ferromagnetic curve. As the field increases, a low field diamagnetic signal emerges. However, temperature dependence of electrical resistivity of Nb1222Y did not show superconductivity, but semiconducting nature with a relatively large magnetoresistance (∼6% at almost entire region). No specific heat anomaly was observed at the vicinity of the transition temperature.