High pressure synthesis and characterization of YSr2Cu3OW

We report the synthesis under pressure, the critical temperature and the st ructural characteristics of YSr2Cu3Ow. The compound does not form at normal pressure, but, once formed, can be retained at normal pressure in a metast able state. The synthesis was carried out in a multi-anvil apparatus at 30 kBars and 1050 degreesC. The as-prepared sample was found to become superco nductor with a Te of approximate to 63K. Tc increased up to approximate to 70 K after annealing in oxygen at 290 degreesC. The refinement of the neutr on diffraction data indicated that the as prepared YSr2Cu3Ow. is tetragonal (a=3.7855 Angstrom and c=11.386 Angstrom) and the oxygen content, w, is ap proximate to 6.84.