The Study On Luminescence Properties Of Lanthanide-doped BaCaLu₂F₁₀ Upconversion Materials

The lanthanide-doped fluoride upconversion luminescence materials usually contain matrix,sensitized ions and activated ions.The sensitized ions with large absorption cross section and activated ions with matching energy levels are co-doped in the fluoride matrix with lower phonon energy.The sensitized ions can absorb photons and transfer energy to the activated ions to achieve strong upconversion emission.The commonly used rare earth ions are Tm³⁺,Nd³⁺and Er³⁺.They have a typical stepped energy level distribution and are suitable for activated ions.The Yb³⁺ions are commonly used sensitized ions under 980 nm excitation,because the energy difference between the ground state and excited state of Yb³⁺ion matches a 980 nm photon energy.So they has a large absorption cross section for infrared light at 980 nm.The most important thing is that their energy level matches the energy of Er³⁺and Tm³⁺.In this paper,we first mainly studied the dual-mode temperature sensitive fluorescence phenomenon of Yb-Er-Tm-V system in BaCaLu₂F₁₀ matrix.Second,we studied the near-infrared luminescence and luminescence enhancement of Yb-Nd system in BaCaLu₂F₁₀ matrix.The main contents are as follows:We prepared the BaCaLu₂F₁₀ host via hydrothermal method.A series of monodisperse spherical micro-nanocrystals of Yb-Er-Tm co-doped were prepared based on the energy level characteristics of Er³⁺and Tm³⁺ions.But the Yb-Er-Tm system did not appear the dual-mode temperature sensitive fluorescence phenomenon what we expected.We doped several metal ions and transition metal ions in the Yb-Er-Tm system according to some special ions can enhance luminescence.The luminescence intensity of the Yb-Er-Tm-V system is 120 times than the Er-Tm system.And the Yb-Er-Tm-V system appeared dual-mode temperature-sensitive fluorescence phenomenon.Through a series of characterizations,we expound a possible up-conversion mechanism for the Yb-Er-Tm and Yb-Er-Tm-V system.Meanwhile,We also can expound the reasons for appearing the dual-mode temperature-sensitive fluorescence phenomenon and the enhanced luminescence from UC emission mechanism in Yb-Er-Tm-V system.The unique energy level structure of Nd³⁺ions makes it possible to realize a wide range of luminescence from the ultraviolet to the near-infrared range.This luminescence characteristic has aroused researcher great interest.In order to make the sample better applied in the biological field,we prepared the Yb-Nd co-doped upconversion micro/nano particles via hydrothermal method.Through a series of characterization of the samples,it was found that the emission spectrum of Nd³⁺ions shows strong broadband near-infrared emission in the biological window range of720⁹50 nm.This type of upconversion material has less influence on biological tissues,higher penetration of excitation light and shows better biocompatibility.In order to enhance the luminescence of Nd³⁺ions,we systematically explored the effects of Er³⁺ions,Fe³⁺ions and Mn²⁺ions on the phase structure and the luminescence performance of Nd³⁺ions.Finally,the luminescence mechanism of Nd³⁺ions was explained.