V-containing ZrO2 inorganic yellow nano-pigments prepared by hydrothermal approach

Recent results on the preparation, characterization and color properties of the V-containing ZrO2 inorganic yellow nano-pigment are reported. A series of monoclinic V-ZrO2 solid solution nanocrystals (VxZr1-xO2, being x = 0, 0.1, 0.02, 0.03, 0.04, 0.05, 0.065, 0.08 and 0.1) were prepared straightforward by hydrothermal processing of mixtures of zirconyl nitrate and ammonium metavanadate in water. Interestingly, the crystalline precipitated obtained by hydrothermal processing at 140 degrees C for 3 d was almost entirely V-containing ZrO2 nanocrystals with the structure of monoclinic zirconia for the whole range of compositions. Lattice parameters changes along the series of prepared samples annealed at 700 degrees C indicated the increase of vanadium content inside the monoclinic vanadium-zirconia crystalline phase up to the nominal amount of vanadium of x = 0.05. Transmission and scanning electron. micrographs of the hydrothermal precipitates showed the formation of defined sets of loosely assembled primary nanocrystals sized 3-4 nm in a disc-like larger motif sized in the range between 25 and 70 nm, depending on the nominal amount of vanadium dopant. Further annealing at 700 degrees C for 1 h gave rise to compact, discrete, morphologically well-defined secondary nanocrystals without size changes and with improved chromatic coordinates. The high stability in aqueous dispersion and the structural and microstructural characteristics of the prepared and annealed nanocrystals up to 1200 degrees C made them good candidates as nano-pigments for digital decoration. Finally, the advantages of the hydrothermal approach against other non-conventional methods for the preparation of V-ZrO2 nano-pigments, such as sol-gel and polyol, will be discussed. (C) 2017 Elsevier Ltd. All rights reserved.