It was noted that up to 10at%Cu readily replaced Ce in ceria. It was found that, at O partial pressures of between 0.21 and 10−5atm, CuxCe1−xO2−δ (0 ≤ x ≤ 0.10) solid solutions behaved as an oxide-ion electrolyte. Moreover, Cu0.10Ce0.90O2−δ exhibited an oxide-ion conductivity of about 10−4S/cm at 600C at an O partial pressure of 10−5atm.

Oxide-Ion Conductivity in CuxCe1−xO2−δ (0 ≤ x ≤ 0.10). A.Gayen, K.R.Priolkar, A.K.Shukla, N.Ravishankar, M.S.Hegde: Materials Research Bulletin, 2005, 40[3], 421-31