Oxide ionic and electronic conduction in Ni-doped LaGaO₃-based oxide

Partial electronic conduction in Ni-doped LaGaO₃-based oxide was investigated by using the ion-blocking method. It was seen that the hole and the electronic conduction originated from doped Ni becomes dominant with decreasing temperature and also with increasing Ni content. PO₂ dependences of hole and electronic conduction decrease with increasing Ni content and it becomes almost P_O2^-1-12 and P _O2^-1/12, respectively, at 1073 K when 10 mol% Ni is doped to Ga site. The estimated transport number of oxide ion in Ni-doped LaGaO ₃ is always higher than 0.95 in P_O2 range from 1 to 10^-21 atm, which is the important P_O2 range for fuel cell application. Therefore, the main charge carrier is still oxide ion in Ni-doped LaGaO₃- Comparing with the partial electronic conduction in Co-doped sample, the electrolyte domain is wider on Ni-doped sample.