AMORPHOUS SILICA-TITANIA COMPOSITE OXIDE POWDER, RESIN COMPOSITION, LIQUID DISPERSION, AND METHOD FOR PRODUCING SILICA-COATED SILICA-TITANIA COMPOSITE OXIDE POWDER

Provided is amorphous silica-titania composite oxide powder which, when a resin or the like is filled with the amorphous silica-titania composite oxide powder for use, provides an excellent fluidity and a good transparency, in comparison to existing silica-titania composite oxide particles. Amorphous silica-titania composite oxide powder is powder untreated with a surface treatment agent and consisting of amorphous silica-titania composite oxide particles, wherein: a refractive index at a measurement wavelength of 589 nm is not less than 1.46; a volume-based cumulative 50% diameter is 0.1 µm to 2.0 µm; and a content of particles having a particle size of not less than 5.0 µm is not more than 10 ppm, and wherein, in a case where the powder is dried in an atmospheric air at 110°C for 12 hours, and powder thus dried is stored for 24 hours at a temperature of 25°C and a relative humidity of 85% so as to absorb moisture, a water absorption rate is not more than 0.8% by mass as calculated from a mass X before moisture absorption and a mass Y after the moisture absorption in accordance with the formula: (Y-X)/X × 100. The amorphous silica-titania composite oxide powder can be produced by exactly adjusting silica coating conditions in production of a silica-coated silica-titania composite oxide and carrying out firing at not lower than 900°C.