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We report superconductivity in the SmFe0.9Co0.1AsO system being prepared by most easy and versatile single-step solid-state reaction route. The parent compound SmFeAsO is non-superconducting but shows the spin density wave ( SDW) like antiferromagnetic ordering at around 140 K. To destroy the antiferromagnetic ordering and to induce the superconductivity in the parent system, the Fe2+ is partially substituted by Co3+. Superconductivity appears in SmFe0.9Co0.1AsO system at around 14 K. The Co doping suppresses the SDW anomaly in the parent compound and induces the superconductivity. Magnetization measurements show clearly the onset of superconductivity with T at 14 K. The isothermal magnetization measurements exhibit the lower critical fields ( Hc1) to be around 200 Oe at 2 K. The bulk superconductivity of the studied SmFe0.9Co0.1AsO sample is further established by open diamagnetic M( H) loops at 2 and 5 K. Normal-state (above Tc) linear isothermal magnetization M( H) plots excluded the presence of any ordered magnetic impurity in the studied compound. [ABSTRACT FROM AUTHOR]

We have performed a systematic study on the occurrence of superconductivity in Nb1− x Mg x B2 (0.0≤ x≤0.40). X-ray diffraction and magnetization measurements are carried out to determine the changes in lattice parameters, superconducting transition temperature ( T c ) and critical field ( H c1). The substitution of Mg at Nb site results in considerable stretching of c-parameter with only a slight change in a parameter. Rietveld analysis on X-ray diffraction patterns gives a=3.11 Å and c=3.26 Å for pure NbB2 while a=3.10 Å and c=3.32 Å for Nb0.60Mg0.40B2. This increased c-parameter introduces superconductivity in niobium diboride. Magnetization measurements though indicate the absence of superconductivity in NbB2, the same shows a clear diamagnetic signal at about 10 K for Nb0.60Mg0.40B2 sample. The magnetization M( H) plots exhibit weak superconductivity like hysteresis loops. The stretching of c-parameter from around 3.26 to 3.32 i.e. by 0.06 cannot be explained solely by substitution of Nb by Mg in the lattice. It seems that some Nb deficiencies are introduced in the Nb1− x Mg x B2 as Mg is not substituted completely at the vacant Nb sites. This could be seen from XRD results, where one can clearly notice the presence of small amount of MgO in Nb1− x Mg x B2 samples. [ABSTRACT FROM AUTHOR]

We report an easy and versatile one-step synthesis route for a newly discovered Fe based LaFeAsO1− δ compound with 0.0≤ δ≤0.15. Instead of widely used high-pressure-high-temperature ( HPHT) synthesis, we applied the normal atmosphere solid-state reaction route. The stoichiometric mixtures of Fe, La2O3, La, and As in ratio LaFeAsO1− δ with 0.0≤ δ≤0.15 are sealed in an evacuated quartz tube and further heated at 500, 850, and 1,100 °C in Ar for 12, 12, and 33 hours, respectively, in a single step. The resulting compounds are single phase LaFeAsO crystallized in tetragonal P4/ nmm structure. These samples showed the ground state spin density wave ( SDW) like metallic behavior below around 150 K. In conclusion, the ground state (non-superconducting) of newly discovered Fe based superconductor is synthesized via an easy one-step solid-state reaction route. [ABSTRACT FROM AUTHOR]

We report an easy and versatile one-step synthesis route for a newly discovered Fe based LaFeAsO1− δ compound with 0.0≤ δ≤0.15. Instead of widely used high-pressure-high-temperature ( HPHT) synthesis, we applied the normal atmosphere solid-state reaction route. The stoichiometric mixtures of Fe, La2O3, La, and As in ratio LaFeAsO1− δ with 0.0≤ δ≤0.15 are sealed in an evacuated quartz tube and further heated at 500, 850, and 1,100 °C in Ar for 12, 12, and 33 hours, respectively, in a single step. The resulting compounds are single phase LaFeAsO crystallized in tetragonal P4/ nmm structure. These samples showed the ground state spin density wave ( SDW) like metallic behavior below around 150 K. In conclusion, the ground state (non-superconducting) of newly discovered Fe based superconductor is synthesized via an easy one-step solid-state reaction route. [ABSTRACT FROM AUTHOR]