Hydrothermal-mediated synthesis of orange Cr, Sb-containing TiO2 nano-pigments with improved microstructure

Abstract

A hydrothermal-mediated via was developed to prepare discrete, non-aggregated Cr,Sb-doped rutile nano-pigments. After annealing the Cr- and Sb-containing TiO2 anatase nanocrystals obtained by hydrothermal aging the nano-pigments Cr,Sb-TiO2 were characterized with the aid of X-ray diffraction (XRD) including lattice parameter and crystallite size determination, Raman spectroscopy, field emission scanning and transmission electron microscopies (FESEM and TEM, respectively) including energy-dispersive X-ray (FESEM/EDX) spectroscopy, high resolution transmission electron microscopy (HRTEM) including selected area electron diffraction (SAED), ultraviolet–visible diffuse reflectance (UV–Vis DR) spectroscopy and chromatic coordinates determination. SEM and TEM micrographs of short annealed anatase-based intermediates at 800 °C proved the formation of monocrystalline Cr,Sb-TiO2 rutile nanocrystals sized under 60 nm with well-defined morphologies. The chromatic coordinates of the rutile-based nano-pigments, both as-prepared and after glazing, reached similar values to those displayed by conventional micrometrics and of those already reported non-conventional nanometric orange pigmenting systems. Zeta (ζ) potential measurements of aqueous dispersions of the prepared nano-pigments indicated good dispersability. The optimum microstructural features of the prepared nano-pigments by the hydrothermal-mediated approach could facilitate the application of these nano-pigments by ink-jet printing.The results obtained in this paper confirmed the solid solution nature of this nano-pigmenting system in the whole range of the studied compositions as well as proved the feasibility of the proposed synthetic approach for the preparation of nano-pigments even when some structural stabilization by additional thermal annealing is required.