Nanocrystalline titania phosphors co-doped with yttrium, europium, and niobium (Yx-zEuzTi1-2xNbxO2, x = 0, 0.10, and 0.15, z = 0-x) were directly formed as a single phase of anatase-type structure from the precursor solutions of TiOSO4, NbCl5, YCl3, and EuCl3 under mild hydrothermal conditions at 100-240 degrees C using the hydrolysis of urea. The crystallite size of the anatase synthesized at 240 degrees C was in the range of 14-20 nm, though it gradually increased with increased hydrothermal treatment temperature. The nanocrystalline titania can be excited by ultraviolet light 395 nm and blue light 465 nm (f-f transitions), and emits orange (590 nm) and red light (611 nm) with line spectra corresponding to D-5(0) -> F-7(1) and D-5(0) -> F-7(2) transitions, respectively. The nanocrystalline anatase synthesized at 120 degrees C showed the highest photoluminescence intensity in the as-prepared samples. The photoluminescence intensity was improved and the Red-to-Orange (D-5(0) -> F-7(2)/D-5(0) -> F-7(1)) (R/O) emission intensity ratio increased from 2.5-2.7 to 3.6-4.0 via the formation of composite particles that consisted of anatase and euxenite phase after heat treatment at 950 degrees C. The anatase-to-rutile phase transformation shifted to higher temperature via co-doping niobium, yttrium, and europium into TiO2. (C) 2013 Elsevier B.V. All rights reserved.