Effect of Ca2+ or Mg2+ additions on the electrical properties of yttria doped ceria electrolyte system

► Effect of co-doping Ca2+ or Mg2+ and Y3+ on ceria was investigated. ► Co-doping with correct ratio showed high conductivity and low activation energy. ► Total conductivity of co-doped samples increases with the increase of dopant. ► Grain boundary has a large influence due to co-doping than that of the bulk.