BaTiO₃, SrTiO₃, CaTiO₃, and Ba_xSr_1−xTiO₃ Particles: A General Approach for Monodisperse Colloidal Perovskites

We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica−titania composite particles by addition of a silica precursor to the titania particles ( Chem. Mater., 2009, 21, 979). Here we show that the principle is general and can be used to prepare different titania-based composite beads. We demonstrate the synthesis of colloidal perovskites like BaTiO 3, SrTiO 3, CaTiO 3 and Ba 0.5 Sr 0.5 TiO 3, which have importance for the electronics industry for their dielectric properties. Mixed perovskites like Ba x Sr 1− x TiO 3 bring tunability in structure and properties by changing the ratio of metal cations. We also show fabrication of metal core, BaTiO 3 shell particles, which could find applications in percolative capacitors, and luminescence properties of Pr 3+ doped colloidal perovskites.