Synthesis and rheological properties of TiO₂-oil nanofluids

The rheological and electrical dynamic control responses of TiO₂ nanofluids and La doped TiO₂ nanofluids have been investigated, respectively. The TiO₂ nanoparticles were prepared via utilizing solvothermal method. The TiO₂ and La doped TiO₂ are anatase with the average size of 18.7 nm. The nanofluids are highly transparent and exhibit good stability. The viscosity of TiO₂ nanofluid was only 42.4 mPa·s without external field. When an external electric field is applied, the viscosity of TiO₂ nanofluid decreases as the strength of the electric field, whereas the viscosity of La doped nanofluid is increased with the electric field. A maximum enhancement of 35% was obtained for 3% doped La nanofluid. The discrepancy of the electrorheology behavior between these two nanofluids is mainly due to the significant improvement of dielectric property of the La doped TiO₂.