RT Journal Article
T1 Towards blue long lasting luminescence of Eu/Nd doped calcium aluminate nanostructured platelets via the molten salt route
A1 Rojas-Hernandez, Rocío E.
A1 Rubio-Marcos, Fernando
A1 Serrano, Aida
A1 Salas Colera, Eduardo
A1 Hussainova, Irina
A1 Fernandez, José Francisco
AB Calcia-alumina binary compounds doped with rare earths and some transition metals cations show persistent luminescence from the visible to the infrared range. Specifically, the blue light can be obtained through the Eu2+ activator center in a potential host, such as dodecacalcium hepta-aluminate (Ca12Al14O33) and monocalcium aluminate (CaAl2O4). By doping with Nd3+, the persistent luminescence can be substantially prolonged; for this reason, the Eu/Nd pair is a potential choice for developing long-lasting blue luminescence. Herein, the phase evolution of the calcia-alumina system via molten salt synthesis is reported as a function of the synthesis temperature and the atmospheric environment. The fraction of CaAl2O4 phase increases when the temperature is higher. Synthesized microparticles of platelet-type morphology represent isolated nanostructured ceramic pieces. Under visible light, the particles are white. This indicates that the followed process solves the dark-gray coloring of phosphor when is synthesized in a reduced atmosphere at high temperature. As regards the synthesis mechanism, which is assisted by the molten flux, the dissolution−diffusion transport process is promoted at the surface of the alumina microparticles. In fact, the emission intensity can be modulated through the phase of the Eu-doped calcium-aluminate discrete platelets synthesized. Consequently, the photoluminescence intensity depends also on the oxidation state of the Eu ion. X-ray absorption near-edge structure and photoluminescence measurements corroborate the Eu reduction and the grain coarsening with the enhancement of the blue emission. The doped phosphors with Eu/Nd show a broad and strong absorption in the region of 320–400 nm and a broad emission band at around 440 nm when they are excited in this absorption range. From a broader perspective, our findings prove that the Ca12Al14O33 and CaAl2O4 phases open new opportunities for research into the design of blue long-lasting emitters for a wide range of fields from ceramic to optoelectronic materials.
PB MDPI
SN 2079-4991
YR 2019
FD 2019-10
LK https://hdl.handle.net/10016/36534
UL https://hdl.handle.net/10016/36534
LA eng
NO This article belongs to the Special Issue Luminescent Rare-Earth Based Nanomaterials.
NO This work was supported by the Spanish Ministry of Science Innovation and Universities (MICIU) under the projects MAT2017-86450-C4-1-R and RTI2018-095303-A-C52, and the Spanish National Research Council (CSIC) under the project NANOMIND CSIC 201560E068. R.E.R.-H. acknowledges the financial support of the Mobilitas Pluss program in the framework of the MOBJD254 project. F.R.-M. is indebted to MINECO for a "Ramon y Cajal" contract (ref: RyC-2015-18626), which is co-financed by the European Social Fund. F.R.-M. also acknowledges support from a 2018 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. A.S. acknowledges the financial support from the Comunidad de Madrid for an "Atracción de Talento Investigador" contract (No. 2017-t2/IND5395). The support of ETAG through PUT1063 (I. Hussainova) is also acknowledged. We acknowledge the Spanish CRG BM25-SpLine, MICIU, CSIC and The European Synchrotron (The ESRF) for the use of the synchrotron radiation facilities, hospitality and financial help.
DS e-Archivo
RD 1 sept. 2024