Abstract
We have measured the electrical resistivity, thermoelectric power, magnetic susceptibility, Hall coefficient and upper critical field near
T
c in EuBa
2Cu
3O
x
, where 6.09<
x<7.0. These data suggest a Mott-Hubbard-like transition near a critical oxygen concentration
x
c∼6.4–6.5. Our results, combined with those reported elsewhere, show a striking similarity between the addition of oxygen to EuBa
2Cu
3O
6 and the substitution of divalent atoms M for La in La
2-
y
M
y
CuO
4. We suggest that superconductivity in both systems is associated with the Cu-O planes and is driven electronically.