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Microemulsion‐Mediated Synthesis and Properties of Uniform Ln:CaWO 4 (Ln = Eu, Dy) Nanophosphors with Multicolor Luminescence for Optical and CT Imaging
Author(s) -
Laguna Mariano,
Núñez Nuria O.,
Garcia Francisco J.,
Corral Ariadna,
ParradoGallego Ángel,
Balcerzyk Marcin,
Becerro Ana I.,
Ocaña Manuel
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700650
Subject(s) - luminescence , phosphor , tetragonal crystal system , persistent luminescence , chemistry , excited state , doping , microemulsion , analytical chemistry (journal) , nanotechnology , phase (matter) , materials science , pulmonary surfactant , optoelectronics , atomic physics , organic chemistry , physics , biochemistry , thermoluminescence
A new room‐temperature method has been developed that yields, for the first time in the literature, uniform and well‐dispersed CaWO 4 nanospindles. This method is based on the use of microemulsions consisting of aqueous solutions of Ca 2+ and WO 4 2– precursors, cyclohexane as the organic medium, Triton X‐100 as the surfactant, and n ‐octanol as the cosurfactant. We show that the formation of uniform nanospindles requires a restrictive set of experimental conditions. These particles crystallize into the tetragonal CaWO 4 phase and emit blue–green luminescence when excited by UV radiation. The reported method is also useful for doping the CaWO 4 spindles with Eu 3+ or Dy 3+ cations, resulting in multicolor emissions (red for Eu 3+ ; white for Dy 3+ ). The luminescence is much stronger when excited through a WO 4 2– –Ln 3+ (Ln = Eu or Dy) energy‐transfer band than through the f–f transition bands of the Ln 3+ cations. Interestingly, because of the white luminescence associated with the Dy:CaWO 4 nanophosphor, it might be useful for LED technologies. Luminescence dynamics and energy‐transfer efficiency have been analyzed to determine the optimum phosphors. Finally, the Eu‐doped CaWO 4 nanospindles also showed excellent X‐ray attenuation efficacy, which confers double functionality to this material as both a luminescence bioprobe and as a contrasting agent for X‐ray computed‐tomography.