Dependence of Upconversion Luminescence and Morphology on the Host Materials
نویسندگان
چکیده
Crystal structure, morphology, and optical properties of Tm, Er, and Yb ions doped four types of host materials [NaLnF4, Ln=Y, Lu, Gd, La] have been investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra were used to characterize the samples. For La-based fluoride, the as synthesized microcrystals are assigned to LaF3 crystal phase. For the other three hosts, hexagonal NaREF4 crystal phase accordingly formed. By changing the dopant’s species, strong multicolor upconversion (UC) emissions can be obtained under 980 nm laser diode (LD) excitation. It is found that the up-conversion luminescence is strongly depended on the host material, particle size, doping substances and concentration and internal structure. Importantly, the intensity ratio of green to red emissions and the intensity ratio of blue to red emissions are highly depended on the property of host materials. The UC mechanisms in the four host materials are also discussed.
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