Preparation of capped metal oxide nanocrystals comprising a metal oxide shell that are photocatalytically and thermally stable and their dispersions in monomers, oligomers, and polymers, as well as the resulting formulations and nanocomposite films. These nanocrystals are highly monodisperse with nanocrystal size between 3-100 n. Resultant formulations incorporating these nanocrystals and a matrix material are highly stable and result in nanocomposites that have high refractive index, are highly transparent, have minimal to no change in absorption upon thermal or UV processing and are optically transparent in the visible wavelengths with very little or no scattering.