高T_c Ba-Y-Cu-O超伝導の焼結前の圧縮による効果

Superconducting transition temperatures have been observed by electrical resistance measurements for the several samples of Ba_2Y_1Cu_30_<7-x> which prepared under compression up to 70kbar before sintering. The onset and end points of the supercoducting transition decreased with increasing pressure. The temperature dependence of electrical resistance for high pressure samples showed a semiconducting behavior in the normal resistance region and the superconducting transition around 60 K indicating the existence of orthorhombic phase-II. The Meissner effect has been measured in order to confirm a superconducting state.