Preparation And Characterization Of Rare-earth Compound Nanomaterials With Switchable Fluorescence

Rare earth luminescent switchable materials have important applications inbiological sensing, biological analysis, high resolution display, integrated opticalsystem, solid lasers, chemical testing and medical diagnosis etc. The properties ofswitchable luminescence indicate that luminescence can be reversibly switchedbetween on and off rapidly as the environmental conditions are changed. In recentyears, tuning and switching of luminescent properties have attracted much attentionwith great expectations for nano-device of applications.YVO₄:Eu nanocrystals are synthesized by hydrothermal synthesis method inour experiments. Luminescent switch is designed on the basis of VO₄^3-/VO²⁺acid-base conversion theory. In order to control the energy transition between hostand activating agent, PH value is adjusted by adding acid and alkali. This processresults in the luminescence or non-luminescence of the Eu³⁺. This means thatnanosized luminescence switching of acid-base is synthesized successfully.Luminescence-switching behaviors of YVO₄:Eu upon redox reactions wereexamined using KMnO₄and vitamin C as an oxidant and a reductant, respectively.Our results demonstrate that highly quantitative and fine-tunable luminescenceswitching is available in YVO₄: Eu which is expected to be helpful for creating anovel fluorescent sensing system for rapid, ultrasensitive and highly selectivedetection of vitamin C.The luminescence properties of rare earth phosphate and vanadate haveacid-base controllability, and only the vanadate have the characteristics withvitamin C for reducing controllable, so by using of acid, vitamin C on rare earthphosphate double adjustment of luminescent properties of composite. Thecontrolling of the yellow-to-blue intensity ratio value of phosphate andorthovanadate composite matrix is synthesized successfully.The CePO₄/CeO₂micrometer crystals have been synthesized on a large scaleusing a higher molar ratio of Ce³⁺and PO₄^3-and adding various kinds of surfaceactive agent by a facile one-step hydrothermal method. It is found that the reactiontime, molar ratio, reagent and surfactant are crucial factors in determining thestructure and morphology of the products. The photoluminescence properties ofCePO₄/CeO₂micrometer crystals are enhanced strongly in comparison with pureCePO₄nanowires due to the synergic effects of CePO₄/CeO₂micrometer crystals.