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New spherical nanocrystalline heterostructures on the basis of Lu2O3:Eu

Yuliya V. Yermolayeva 1Tatyana Korshikova Alexander Tolmachev 

1. Institute for Single Crystals NAS of Ukraine (ISC), 60 Lenin Ave., Kharkov 61001, Ukraine

Abstract

It is known that lutetium oxide is the effective host for rare-earth dopants. Nowadays nano-sized Lu2O3 doped with Eu3+ ions is considered as one of the most perspective materials for X-ray detection and imaging and also new X-ray phosphors creation due to its high density (=9.42 g/cm3) and high effective atomic number Zeff.=71. However, preparation of Lu2O3 spherical particles with narrow size distribution by conventional soft chemistry methods meets some difficulties, which is limited of the nanostructured scintillation materials creation on the lutetium oxide basis. Development of the method of the spherical Lu2O3:Eu3+ particles preparation with the given sizes and heterostructures on their basis opens up the possibilities of the creation of the effective X-ray screens, high-resolution displays with improved characteristics and also photonic matrixes preparation with the diffraction enhancement of the luminescence light. Monosized Lu2O3:Eu3+ spherical particles (diameter range from 60 to 300 nm) and core-shell heterostructures on their basis (Lu2O3:Eu3+/SiO2, SiO2/Lu2O3:Eu3+/Lu2O3) were prepared for a first time. The structure, morphology and X-ray luminescent properties were studied in this work. Lu2O3:Eu3+ spherical particles were prepared by the co-precipitation technique from water solutions with subsequent heat treatment. Europium content in the samples was ranged from 1 to 10 аt. %. Lu2O3:Eu3+/SiO2 core-shell heterostructures were synthesized according to Stober method. Lu2O3:Eu3+ coverings of the controlled thickness (10-50 nm) were formed on the surface of the SiO2 spheres by the sol-gel technique from water solutions. The shape, sizes, phase composition of the heterostructures prepared were studied by means of electron microscopy methods, X-ray diffraction, X-ray photoelectron and FT-IR spectroscopy. The temperature conditions of the crystallization and morphology properties of the Lu2O3:Eu3+ solid-state solutions in the form of spherical particles and nanolayers onto SiO2 spheres were investigated. Lu2O3:Eu3+→ Lu2SiO5:Eu3+ → Lu2Si2O7:Eu3+ structural transformations in the heterostrucrures prepared in the 900 – 1200 ºС temperature range were observed. The features of Eu3+ entering in the low dimensional systems were also discussed. The X-ray luminescent properties of the Lu2O3:Eu3+ spherical particles and Lu2O3:Eu3+/SiO2, SiO2/Lu2O3:Eu3+/Lu2O3 heterostructures were studied. Under X-ray excitation europium-doped nanophosphors obtained are characterized by effective luminescence in the =575–725 nm range corresponding to 5D07FJ transitions (J=04) of Eu3+ ions in the crystalline host. It has been shown that radioluminescence intensity of the heterostructures strongly depends on the phase composition, shells thickness and Eu3+ dopant concentration.

 

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Related papers

Presentation: Oral at E-MRS Fall Meeting 2009, Symposium H, by Yuliya V. Yermolayeva
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-02 14:27
Revised:   2009-06-07 00:48