The Effect of Solvents and Rare-Earth Element (Er, Yb) Doping on Suspension Stability of Sol–Gel Titania Nanoparticles

The effects of solvent on the suspension stability of titanium dioxide (TiO
₂
) nanoparticle (NP)-doped rare-earth elements (Er and Yb) were evaluated. Pure and doped TiO
₂
NPs were successfully prepared by the sol-gel method under the supercritical drying conditions of ethanol. Doped nanopowders were prepared with 5 mol% Er or 5 mol% Yb concentration, and co-doped nanopowders were prepared with fixed 5 mol% Er concentration and various Yb concentrations of 5 and 10 mol%. TiO
₂
NP suspensions with diverse solvents, such as water, ethanol, methanol, and butanol, were prepared. The nanopowders were characterized by studying their structural and morphology properties. The NP size analysis revealed the average size of TiO
₂
as approximately around 7-12 nm. Suspensions of TiO
₂
NPs in different solvents were prepared by a two-step powder dispersion process using several ultrasonication methods. The aim of this paper was to prepare a stable suspension for a certain time period and then to produce doped and undoped TiO
₂
NP coatings for photovoltaic application. The effects of concentration, dopants, and solvents on the dispersibility and stability of TiO
₂
suspensions were evaluated. The UV-visible spectroscopy, zeta potential measurements, particle size distribution, SEM, and Hamaker 2 software confirm that the 5%Er-10%:TiO
₂
suspension exhibits a good stability and stable suspension improved by co-doped rare.