X-ray Irradiation Time Behavior of Exciton Luminescence for Yttria Sintered from Nanosized Powder

We measured 60 keV X-ray induced exciton luminescence with maximum at 4.56 eV for polycrystalline yttria ceramics sintered from nanosized powder. In order to test our previously proposed model based on photoelectron trapping by intergrain caverns, we carried out the mathematical treatment of the experimental time dependence of exciton luminescence intensity at different photon energies. It was established that the experimental curves are best described by two-component exponents, which indicates two types of photoelectron traps. The dominant role of small-sized caverns compared to larger ones was revealed, which is in a good agreement with our model. The relaxation rate of the captured photoelectrons from the small caverns should indeed be higher than from bigger ones.