The solid solutions Ce 1- x Eu x O 2- δ ( x =0\^10—0\^50) were synthesized by high temperature and high pressure. The XRD measurement showed that the solid solution was crystallized in cubic fluorite type structure and the lattice parameter increased with the content of Eu increasing up to x =0.4. The solution limit was \%ca.\% 0.4 under the condition of 3.6 GPa, 840—1 020 ℃. The XPS data showed that the Eu ions are Eu 3+ and trace of Ce 4+ ions were reduced to Ce 3+ ions during synthesis of high temperature and high pressure. The ionic conduction for Ce 0.8 Eu 0.2 O 2- δ was measured by impedance spectroscopy and it was found that the activation energy was 1.07 eV and the conductivity was 3.43×10 -5 S·cm -1 at 550 ℃.
