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Importance of Volume Ratio in Photonic Effects of Lanthanide‐Doped LaPO 4 Nanocrystals
Author(s) -
Luo Yuxia,
Li Liyi,
Wong Hon Tung,
Wong KaLeung,
Tanner Peter A.
Publication year - 2020
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201905234
Subject(s) - materials science , quantum yield , analytical chemistry (journal) , doping , lanthanide , nanocrystal , absorption (acoustics) , surface area to volume ratio , chemistry , ion , nanotechnology , optics , thermodynamics , fluorescence , optoelectronics , organic chemistry , physics , composite material
Experimental variation of the volume ratio (filling factor: i.e., volume of nanoparticles (NPs) compared with that of medium) of nanocomposite materials with doped lanthanide ions demonstrates that it has a significant affect upon local field effects. Lanthanum orthophosphate NPs are doped with Eu 3+ and/or Tb 3+ and immersed in organic solvents and lead borate glasses for Tb 3+ 5 D 4 lifetime measurements. For media with a refractive index ( n med ) less than that of LaPO 4 ( n np = 1.79), the 5 D 4 emission decay rate increases with increasing volume ratio of the NPs, whereas for n med > 1.79, the decay rate decreases with increasing volume ratio. Fitting with the model of Pukhov provides an estimation of the radiative lifetime of 5 D 4 and the quantum yield. Energy transfer (ET) from Tb 3+ to Eu 3+ occurs in co‐doped LaPO 4 NPs with excitation into a Tb 3+ absorption band. The ET rate is independent on n med and the energy transfer efficiency decreases with an increase in n med . The behavior of ET rate with regard to the local field is consistent with the Dexter, but not Förster, equation for ET rate involving the electric dipole–electric dipole mechanism. This has consequences when using the spectroscopic ruler approach to measure distances between donor–acceptor chromophores.