Complete range Zr1-xCexO2 (0 <= x <= 1) nanoparticles are synthesized by the thermal decomposition of metal-organic precursors (zirconium acetylacetonate and cerium acetylacetonate) in oleylamine. XRD and HRTEM indicate that all of the as-prepared nanoparticles are single-crystal, and the crystallinity becomes better with increasing Ce content. The Zr1-xCexO2 nanoparticles with Ce content larger than 1/8 crystallize in cubic fluorite phase. XRD measurements on the as-prepared and calcinated ZrO2, samples reveal that the tetragonal ZrO2, nanoparticles are stable below 600 degrees C, and the lattice parameters of ZrO2, nanoparticles decrease with decreasing particle size. The thermal stability of the cubic phase increases with increasing Cc content. The UV-vis absorption spectra reveal that the band gap, energy increases with increasing cerium content. Room-temperature photoluminescence (PL) spectra of pure ZrO2, nanoparticles show strong emission peaks centered at about 441 nm at room temperature, which is attributed to the ionized oxygen vacancies in the nanoparticles. On the. other hand, room-temperature PL spectra of the as-prepared CeO2, nanoparticles shows two peaks at 417 and 436 nm, which might arise from the transition from the cerium 4f and to the oxygen 2p band (valence band) in CeO2, and the presence of oxygen vacancies, respectively. (c) 2006 Elsevier B.V. All rights reserved.