The zero resistance behavior of a CuO film sandwiched with YBa2Cu3O7-d
elta films has been examined. The CuO is of tenorite C2/c structure wh
ich is a deformed NaCl-type lattice structure without being separated
by an alkaline earth, and it forms a bulk in which copper is surrounde
d by nearly a square of Oxygen. The transition temperature T-ce (R = 0
) in the fabricated sandwiched-type-CuO optimally increases over that
of YBa2Cu3O-(7-delta) film-electrodes.