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Федеральный исследовательский центр 
«Красноярский научный центр
Сибирского отделения Российской академии наук»

 Федеральный исследовательский центр «Красноярский научный центр Сибирского отделения Российской академии наук»

Федеральный исследовательский центр 
«Красноярский научный центр
Сибирского отделения Российской академии наук»

Enhancement of red emission and site analysis in Eu2+ doped new-type structure Ba3CaK(PO4)3 for plant growth white LEDs

2019 год

Авторы
Molokeev, M. S.
Russian Acad Sci, Siberian Branch, LV Kirensky Phys Inst, Krasnoyarsk, Russia
A novel compound Ba3CaK(PO4)3 (BCKP) with new-type structure was synthesized and its structure was determined by X-ray diffraction Rietveld refinement, in which crystal structure consists of Ba1O9, Ba2O12, Ba3O9, CaO8 and KO10 polyhedra, that"s five cationic sites. As a phosphor host, Eu2+ doped BCKP emits cold white light with about 90% quantum efficiency (QE) through entering different cationic sites. Based on the results of refinement, three Eu2+ luminescence centers in sites Ca, Ba2 and K were clearly assigned in Eu2+ solely doped BCKP by the time-resolved emission spectra (TRES), Van Uitert equation, but the emissions of Eu2+ at Ba1 and Ba3 sites are not easy to be determined for the same coordination number (CN). According to their different spatial distribution of the coordinated atoms, the first-principles calculation was used to compute the d orbital splitting energy of Eu2+ ions in Ba1 and Ba3 sites to accurately distinguish the ambiguous luminescence centers. In order to meet the requirement of plant growth spectra, Mn2+ was introduced into BCKP: Eu2+ to enhance the red component of spectra, which not only perfectly match with the absorption spectra of carotenoid and chlorophyll-b, but also LEDs fabricated through combining 365 nm near ultraviolet (n-UV) chip with BCKP: Eu2+, Mn2+ phosphor exhibit excellent parameters including high color rendering index (Ra) (92), excellent correlated color temperature (CCT) (4486 K) and outstanding QE up to 65%. Results confirmed that BCKP: Eu2+/Mn2+ phosphor with great potential applications in white LEDs and plant growth. © 2018 Elsevier B.V.


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