The stability of optical properties under irradiation for ZnO micropowder modified with TiO2 nanoparticles.

It has been experimentally proven for the first time that nanoparticles deposited on the surface of a micropowder perform the role of relaxation centers for the primary defects induced by radiation. This article focuses on the results of studying the radiation stability of ZnO powders modified with TiO 2 nanoparticles. The study shows the presence of the three processes that pre-determine the change of diffuse reflectance spectra and solar absorptance: 1) TiO 2 powders deposited on the surface of micropowder grains perform the role of a protective layer by absorbing a part of incident radiation; 2) when exposed to radiation, primary defects are formed inside a micropowder, that is, electron – hole pairs transforming into intrinsic defects; 3) the nanoparticles act as relaxation centers for primary defects formed inside the grains and granules of micron-size particles, which reduces the concentration of the former. • Optical properties stability while irradiating nano-TiO 2 is lower than that for micro-/nano-ZnO. • Modifying ZnO micropowders with nano-TiO 2 leads to an increase in radiation stability. • Nanoparticles act as relaxation centers for the post-irradiation primary defects. • Sample irradiation and diffuse reflectance spectra measurement were conducted in vacuum. [ABSTRACT FROM AUTHOR]