Spectroscopic study and enhanced thermostability of combustion-derived BaMgAl10O17:Eu2+ blue phosphors for solid-state lighting

• Published in: Optical materials 2017-02, Vol.64, p.334-344
• Main Authors: Pradal, Nathalie, Potdevin, Audrey, Chadeyron, Geneviève, Bonville, Pierre, Caillier, Bruno, Mahiou, Rachid
• Format: Article
• Language: English
• Subjects: Combustion derived BAM:Eu; LEDs; Physics; Solid-state lighting; Thermal stability
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2016.12.031

Blue-emitting BaMgAl10O17:Eu2+ (BAM:Eu), suitable for applications in a next generation of Hg-free lamps based on UV LEDs, was prepared by a microwave induced solution combustion synthesis, using urea as combustion fuel and nitrates as oxidizers. Purity control of the as-synthesized blue phosphor was undertaken by a washing step followed by a reduction one. Structural and morphological properties of the outcoming phosphors have been considered. Synthesis process allows producing a well-crystallized and nanostructured BAM phase within only few minutes. The influence of reduction treatment on the relative amounts of Eu2+/Eu3+ in our samples has been investigated through an original study by magnetization and Mössbauer spectroscopy. Furthermore, a complete optical study has been carried out and allowed us to determine the europium localization in the three possible sites in BAM matrix. The percentage of Eu2+ increased twofold after the reduction treatment, entailing an increase in the luminescence efficiency upon UV excitation. Finally, temperature-dependent luminescence of combustion-derived powders has been studied till 170 °C and compared to that of commercial BAM:Eu. MISCS-derived phosphors present a higher thermal stability than commercial one: whereas the emission efficiency of this last was reduced by 64%, the one of combustion-derived BAM:Eu experienced an only 12% decline. Furthermore, while commercial BAM suffered from a severe blue-shift with increasing temperature, our phosphors keep its color quality with a good stability of the photometric parameters. [Display omitted] •BAM:Eu phosphor has been synthesized through a simple and fast combustion procedure.•Optical study showed that Eu2+ ions mainly occupied anti-Beevers-Ross sites.•These phosphors showed a higher stability of optical properties than commercial one.•These phosphors are promising candidates for near-UV based solid-state lighting.