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Hydrothermal Synthesis of Nb ‐ and Eu ‐ Co ‐Substituted Nanocrystalline Anatase: Eu x Ti 1–2 x Nb x O 2 with Photoluminescence and Photocatalytic Activity: Compositional Dependence of Multifunctional Properties
Author(s) -
Hirano Masanori,
Sato Shingo
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05385.x
Subject(s) - anatase , nanocrystalline material , rutile , materials science , hydrothermal circulation , photocatalysis , photoluminescence , hydrothermal synthesis , chemical engineering , mineralogy , chemistry , nanotechnology , catalysis , biochemistry , optoelectronics , engineering
Nanocrystalline titania ( Eu x Ti 1–2 x Nb x O 2 , x = 0–0.15) co‐substituted with europium ( Eu ) and niobium ( Nb ) having photoluminescence (PL) and photocatalytic activity was formed as a single phase of anatase‐type structure from the precursor solutions of TiOSO 4 , NbCl 5 , and EuCl 3 under mild hydrothermal conditions using the hydrolysis of urea. The amount of Eu and Nb that can be co‐doped into a metastable anatase‐type TiO 2 lattice under hydrothermal conditions was limited up to 15 mol%, respectively, above which the aeschynite EuTiNbO 6 coexisted with anatase. The nanocrystalline titania can be excited by ultraviolet light 395 nm (f–f transition) and emits red light (611 nm) with line spectrum corresponding to 5 D 0 – 7 F 2 transition. The PL intensity increased with increased replacement amount of Eu and Nb . The anatase solid solution co‐doped with 5 mol% Eu and 5 mol% Nb ( x = 0.05) showed a similar activity to pure anatase ( x = 0) on the photodecomposition of methylene blue under UV light irradiation. The anatase‐to‐rutile phase transformation was delayed via the copresence of Eu and Nb component. In the course of heating and the growth of anatase crystallite, a part of the dopants that could not exist in the titania precipitated as euxenite phase EuTiNbO6 from the anatase at 900°C–1000°C before the phase transformation.