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Information × Registration Number 0222U001169, 0119U100918 , R & D reports Title Investigation of mechanisms of redox activity of oxide nanocrystals that contain ions with variable valency (MeVO4, MeWO4, Sr2CeO4) and creation of "nanocrystal - organic molecule" hybrid complexes. popup.stage_title Head Yefimova Svitlana L., Доктор фізико-математичних наукSemynozhenko Volodymyr P., Доктор фізико-математичних наук Registration Date 24-01-2022 Organization Institute for scintillation materials NAS Ukraine popup.description2 Nanoparticles ReVO4:Eu3+ (Re = Gd, Y, La), nanopowders of mixed vanadium-phosphates of yttrium YVxP1-xO4, colloidal solutions of mixed GdY(VO4)х(PO4)1-x and GdY(VO4)х(PO4)1-x:Eu3, nanoparticles CaWO4, and Sr2CeO4, scintillation nanoparticles LaF3:Tb3+ have been synthesized. It has been established that in oxygen-deficient ReVO4:Eu3+ NPs the part of V5+ ions is reduced to V4+, which are stabilized by oxygen vacancies. The key role of the V4+ ions in the antioxidant action of ReVO4:Eu3+ NPs has been established. For the first time, the "dark" generation of reactive oxygen species (ROS) in aqueous solutions containing (Gd,Y)VO4:Eu3+ NPs has been revealed. For the first time, it was found that the pro- or antioxidant properties of gadolinium-yttrium (Gd,Y)VO4:Eu3+ NPs can be dramatically changed depending on the conditions of NPs pre-treatment. It was found that NPs that were pre-treated with UV radiation exhibit prooxidant properties, i.e. effectively generate reactive oxygen species with subsequent UV or X-ray irradiation, while NPs stored in the dark are effective antioxidants. Mechanism for changing the redox properties of gadolinium-yttrium orthovanadate (Gd,Y)VO4:Eu3+ NPs has been proposed. The mechanism of X-ray-induced generation of •OH radicals in (Gd,Y)VO4:Eu3+ NPs has been established for the first time, which can be divided into two processes: (i) direct •OH radicals generation with the participation of thermalized holes h+ formed during X-ray irradiation; (ii) X-ray-stimulated release of h+ formed in the NPs during pre-treatment with UV- light and captured at local levels formed by the random scattering potential over the valence band. A complex with non-radiative electronic excitation energy transfer (UV- and X-ray excitation) between LaF3:Tb3+ NPs and organic photosensitizer Bengal Rose, which efficiently generates singlet oxygen, has been developed. Product Description popup.authors Yefimova Svitlana L. Bespalova Iryna I. Viagin Oleg G. Hubenko Kateryna О. Klochkov Volodymyr K. Maksimchuk Pavlo О. Semynozhenko Volodymyr P. popup.nrat_date 2022-03-09 Close