Features of the Phase Composition and Structure of Eu Doped Y2O3 Submicrospheres

Polycrystalline, non-agglomerated nanopowders based on monosized (Y1-xEux)2O3 submicrospheres were prepared. It was shown that the annealing temperature strongly influences on the structure, mor-phology and composition of the spherical (Y1-xEux)2O3 phosphors obtained. It was found that the concentra-tion quenching effects of Eu3+ luminescence in the (Y1-xEux)2O3 spheres with 70-280 nm diameter is shifted to lower Eu3+ concentrations (x =0,02; 0,05 for 70 and 280 nm spheres respectively) compared with the mi-crocrystalline powders with similar composition (x = 0,09). The reason of this phenomenon probably is for-mation of inhomogeneous phase of (Y1-xEux)2O3 solid solution in the nanopowders with the primary location of bigger Eu3+ ions in the surface area due to active diffusion processes. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3521

Spherical phosphors Lu₂O₃:Eu coated with SiO₂ shells

Amorphous SiO₂ coatings of controlled thickness ranging from 10 to 100 nm have been fixed onto submicron-sized Lu₂O₃:Eu spheres for a first time by Stober method. The morphology, nanostructure, and chemical composition of the resultant Lu₂O₃:Eu/SiO₂ coreshell heteroparticles have been studied. A considerable luminescence decrease was observed for Lu₂O₃:Eu spheres coated with SiO₂ shell as compared to the uncoated phosphors, due to the features of Lu₂O₃:Eu sphere crystallization in a volume bounded by the SiO₂ shell.Вперше аморфні покриття SiO₂ різної товщини у межах 10-100 нм отримано на сферичних субмікрочастинках Lu₂O₃:Eu методом Штобера. Досліджено морфологію, наноструктуру та хімічний склад отриманих гетерочастинок Lu₂O₃:Eu/SiO₂ типу "ядрооболонка". Значне зниження інтенсивності люмінесценції спостерігалося у гетерочастинках Lu₂O₃:Eu/SiO₂ у порівнянні з вихідними частинками Lu₂O₃:Eu, що пов'язано з особливостями кристалізації сфер Lu₂O₃:Eu в обмеженому оболонкою SiO₂ об'ємі.Впервые аморфные покрытия SiO₂контролированной толщины в пределах 10-100 нм получены на сферических субмикрочастицах Lu₂O₃:Eu методом Штобера. Исследованы морфология, наноструктура и химический состав полученных гетерочастиц "ядро-оболочка" Lu₂O₃:Eu/SiO₂. Значительное снижение интенсивности люминесценции наблюдалось в Lu₂O₃:Eu/SiO₂ гетерочастицах по сравнению с исходными Lu₂O₃:Eu частицами, что связано с особенностями кристаллизации Lu₂O₃:Eu сфер в ограниченном оболочкой SiO₂ объеме

Optical properties of CdS and PbS nanocrystals adsorbed on silica nanoparticles

The adsorption mechanism of CdS and PbS semiconductor nanocrystals on the surface of spherical silica particles has been investigated. The presence of quantum size effects in the "core-shell" heteronanostructures with dielectric SiO₂ core and semiconductor shell consisting of nanocrystals has been established. Influence of the core size and a degree of its covering with CdS, PbS nanocrystals on optical properties of heteronanostructures has been shown

Morphology of lead sulfide crystalline particles in size-limited state

Monocrystalline PbS particles of cubic structure ranging in size from 3 to 500 nm, were obtained. Influence of growth conditions on the final particles size and dispersion of lead sulfide nanocrystals, as well as effects of nanocrystals size on their shape have been studied. It was found that increasing of monocrystalline particles size more than 12 nm leads to transition of shape from spherical to cubic, that indicate predominance of surface energy influence on equilibrium geometry of nanocrystals