V-containing ZrO2 inorganic yellow nano-pigments

Abstract

In this work we report new results on the preparation, characterization and color properties of the inorganic yellow nano-pigmenting system based on monoclinic V–ZrO₂ solid solution nanoparticles. The series of solid solution nanopowders were obtained by a polyol technique where the precipitates, obtained after heating at 180 °C ethylene glycol solutions of vanadyl acetonate and zirconium n-propoxide, were annealed at different temperatures up to 1300 °C for a short duration, in order to improve their crystallinity and control the crystalline form of the final nanoparticles. On annealing at around 450 °C highly crystalline tetragonal V-containing zirconia particles were developed, which transform into the monoclinic form of the V–ZrO₂ solid solution after subsequent annealing at 800 °C. Interestingly, the final non-aggregated, well-shaped monoclinic zirconia solid solution particles heated even at as high temperatures as 1000 °C, were sized in the nanometric range displaying well-defined faces and edges. The chromatic coordinates of the prepared nano-pigments after annealing at different temperatures between 800 and 1300 °C indicated yellowness values comparable to conventionally prepared micrometric yellow pigments. The stability of the nano-pigments in aqueous dispersions estimated by zeta potential measurements was good with a low degree of particle aggregation. The used polyol-mediated synthesis can be up-scaled on an industrial level in the preparation of zirconia-based nano-pigmenting systems.