Nanocrystals of Ce1-xMnxO2-δ（x=0.00,0.05,0.10,0.15,and 0.20） were synthesized by a hydrothermal reaction route.The solid solutions crystallized in a cubic fluorite structure with a particle size in the range of 11～15 nm.The incorporation of Mn ions in CeO2 resulted in a lattice volume reduction.Mn ions showed a mixed valence state of ＋2,＋3 and ＋4 in CeO2 lattice.An obvious red-shift of the absorption threshold edge was observed from the UV-visible spectrum.Compared with the bulk CeO2,Ce1-xMnxO2-δ nanocrystals exhibited a lower releasing oxygen temperature as indicated by TPR technique.
