Structure, Delamination and Luminescence of Layered Dysprosium Hydroxides and the Generation of White Light with 2D Crystals

Layered dysprosium hydroxides intercalated with dodecyl sulfate ions (DS(-)LDyHs) have been synthesized using homogenous precipitation technique. Unlike the previously reported DS- intercalated layered europium hydroxides (DS--LEuHs) and layered terbium hydroxides (DS--LTbHs), the resultant DS--LDyHs have mixed host layers of m=1 and m=2 according to the general formula of Dy-2(OH)(6-m)(A(x-))(m/x)center dot nH(2)O. Due to charge difference, the m=1 and 2 types of layers have different basal spacings of similar to 28 and similar to 34 angstrom, corresponding to a monolayer and an alternating antiparallel arrangements of DS- in the interlayers, respectively. Unlike their precursors, the 2D crystals exhibit strong F-4(9/2)-> 6H(13/2) hypersensitive emissions of Dy3+, making them more applicable to the generation of white-bluish lights. The nanosheets also have longer fluorescence lifetime than precursor for 480 nm emission of Dy3+. Colloidal hybrids were prepared by mixing a suspension of the nanosheets of DS--LDyHs, DS--LEuHs and DS--LTbHs to achieve color-tuning in the white-light region under excitations at 284, 318, and 377 nm.