Author/Authors :
Awana، نويسنده , , V.P.S. and Gupta، نويسنده , , Anurag and Kishan، نويسنده , , H. and Takayama-Muromachi، نويسنده , , Pedro E. and Watanabe، نويسنده , , T. and Karppinen، نويسنده , , M. and Yamauchi، نويسنده , , H. Z. Malik، نويسنده , , S.K. and Yelon، نويسنده , , W.B. and Ganesan، نويسنده , , V. and Narlikar، نويسنده , , A.V.، نويسنده ,
Abstract :
A Tb-123 phase with the composition, TbSr2Cu2.7Mo0.3O7+δ, has been synthesized in single-phase form by the solid-state reaction route. Its phase purity has been confirmed from neutron powder diffraction studies. The as-synthesized Tb-123 sample does not show superconductivity down to 5 K. On the other hand, an unusually high antiferromagnetic ordering temperature (TN) of around 7 K is seen for the Tb moments. After 120-atm-O2 post-annealing, bulk superconductivity is achieved in this compound with a superconducting transition temperature (Tc) of about 30 K, without any significant effect on TN. To achieve higher oxygen content and higher Tc, the as-synthesized sample was subjected to high-pressure oxygenation, carried out in a closed cell, at 5 GPa and 400 °C in the presence of AgO as an excess-oxygen source. This sample exhibited superconductivity onset at around 80 K with a Meissner fraction larger than 10% at 5 K. Our observation of superconductivity at 80 K is the highest Tc to-date for the Tb-123 type compounds.
