Anisotropy of Bi₂Sr₂CaCu₂O_y Superconducting Single Crystals Under High Pressure

It is shown that there exists the anisortropic nature of pressure dependence for the superconducting transition temperature and resistivity in Bi₂Sr₂CaCu₂O_y single crystals. The maximum superconducting critical temperature and the minimum resistance along a-b plane under about 8kbar have been observed, no obvious structure phase transition was observed at room temperature under pressure, and there is not the same behaviour along the c axis up to 13kbar. A slight difference between the rates dT_c/dP along a-b plane and c axis was also found. This anisotropy may have close relation to the coupling between layers.