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We have successfully synthesized a new 1222-type Y-based niobio-cuprate for the first time with the chemical composition, NbSr2(Y1.5Ce0.5)Cu2O10 by a high-pressure and high-temperature (HPHT) technique under different synthesis conditions. Good quality (nearly single-phase) Nb1222Y polycrystalline sample was synthesized at 1,450 ○C and 6 GPa for 2 h. It crystallizes in a tetragonal symmetry of space group I4/ mmm with lattice parameters a= b=3.863(2) Å and c=28.687(5) Å, which is isostructural with the corresponding Ru1222Y (RuSr2(Y1.5Ce0.5)Cu2O10) phase. The dc-magnetic susceptibility measurements show a mixed magnetic state at ∼29 K, which is apparently associated with magneto-superconductivity. The magnetic moment ( M) versus field ( H) 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. [ABSTRACT FROM AUTHOR]

57Fe (1%) doped SrCoO3 obtained by high-pressure method, has been investigated by magnetization and Mössbauer spectroscopy studies (MS) in the temperature range 4.2 K to 300 K. The ferromagnetic ordering temperature T C obtained is 272(2) K. Isothermal magnetization curves have been measured at various temperatures, from which the saturation moments ( M sat) have been deduced. The 57Fe MS spectra display standard six-line patterns with an isomer shift typical of Fe3 + and a very small quadrupole splitting (QS = 0.14(1) mm/s above T C). The magnetic hyperfine field at 4.2 K is 276(1) kOe. The temperature dependencies of the iron hyperfine field and M sat (1.83 µ B at 5 K) are almost identical. This shows that the Fe3 + is replacing Co4 + , both of the same electronic configuration. They also interact similarly, namely the Fe–Co exchange is almost identical to the Co–Co exchange. [ABSTRACT FROM AUTHOR]