Ce-doped nanoparticles of TiO2: Rutile-to-brookite phase transition and evolution of Ce local-structure studied with XRD and XANES

► Ce-doping: TiO2 nanoparticles shrink & minority phase changes rutile-> brookite. ► XANES reveals phase change for arbitrarily small particles (while XRD fails). ► As Ce added: fraction of Ce+3 dopants falls, hybridization of Ce+4 with O weakens.