Controlled synthesis and optical spectroscopy of lanthanide-doped KLaF4 nanocrystals
- 25 April 2012
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Nanoscale
- Vol. 4 (15), 4485-4491
- https://doi.org/10.1039/c2nr30794d
Abstract
KLaF4, as a good host matrix for trivalent lanthanide (Ln3+) ions to fabricate upconversion (UC) or downconversion (DC) phosphors, has been rarely reported. Herein, monodisperse (∼10 nm) cubic-phase Ln3+-doped KLaF4 nanocrystals (NCs) were synthesized via a facile thermal decomposition method. Upon excitation at 980 nm, UC luminescence properties of KLaF4:Ln3+/Yb3+ (Ln = Tm, Ho, Er) NCs were comprehensively surveyed. Particularly, after coating an inert KLaF4 shell, the green and red UC luminescence intensity of KLaF4:Er3+/Yb3+ NCs was enhanced ∼35 times, and the corresponding UC lifetimes of 4S3/2 and 4F9/2 levels of Er3+ were observed significantly prolonged from 42 and 68 μs in core-only NCs to 87 and 136 μs in core/shell counterparts. Furthermore, intense DC luminescence was also achieved in Ce3+/Tb3+ and Eu3+ doped KLaF4 NCs, with absolute quantum yields of 39.8% (Tb3+) and 17.3% (Eu3+). The luminescence lifetimes of 5D0 (Eu3+) and 5D4 (Tb3+) were determined to be 4.2 and 4.7 ms, respectively. Water-soluble Ln3+-doped KLaF4 NCs featuring excellent monodispersion, long luminescence lifetime, and high UC/DC efficiency may have versatile and promising applications as luminescent nano-biolabels.Keywords
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