Grain growth and interfacial solid state of CeO2 nanocrystals (NCs) layer on Al2O3(0001) substrate were examined. CeO2 NCs layer on Al2O3(0001) was prepared by dipping method using CeO2 nanocrystals colloid solution. After heat treatment at 1000 degrees C in air, CeO2 NCs layer was formed on Al2O3(0001). The CeO2 NCs sintered to form a surface layer with an interlayer of CeAlO3 after heat treatment at 950 degrees C in H-2/Ar, leading to dense and smooth CeO2 NCs layer on Al2O3(0001) substrate. CeAlO3 was grown via diffusion of CeO2-x,, (non-stoichiometric CeO2) and Al2O3, suggesting solid-phase reaction heteroepitaxy mechanism on Al2O3(0001) single crystal substrate. (C) 2017 Elsevier B.V. All rights reserved.