Comparison of Optical Properties and Radiation Stability of Gd2O3 Micro- and Nanopowders

The results of comparative studies of the phase composition, diffuse reflectance spectra, radiation-induced absorption spectra, and the integral absorption coefficient of solar radiation upon irradiation of micro- and nanopowders of gadolinium oxide are presented. To assess the radiation stability of optical properties, the samples were placed in a chamber of an installation simulating space conditions, where diffuse reflection spectra were recorded in the range of 0.2–2.5 μm in a vacuum of 2 × 10^–6 Torr before and after each period of electron irradiation (E = 30 keV, Φ = (1–3) × 10¹⁶ cm^–2). Micropowders of rare earth elements are used to increase the radiation stability of materials by absorbing free electrons formed in them during irradiation during their transitions from the d- to f-shell. Nanopowders of rare earth elements added to micropowders of various compounds provide an additional mechanism for increasing radiation stability due to the annihilation of primary defects formed during irradiation on nanoparticles. The result obtained in this work is opposite to these mechanisms—the radiation stability of a micropowder is significantly (more than 4 times) higher compared to a nanopowder due to more intense absorption in the ultraviolet region for the nanopowder caused by their own defects. The paper gives an explanation of the results obtained.