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Detailed Program
Paper Number : SY-P01
Time Frame : 12:00~13:30
Presentation Date : Thursday, 27, November
Session Name : Synthesis, Raw Materials & Advanced powder processing
Session Chair 1# : -
Session Chair 2# : -
The Pulsed laser assisted synthesis of Tm3+ doped CaMoO4 colloidal nanocrystals and its upconversion luminescence
Prof.Jungil Lee
Korea National University of Transportation
In recent years, lanthanide ion doped upconversion (UC) luminescence from near infra-red radiation to visible or UV light has received many attention for their various applications in phosphors, solar cell, flat-panel displays, scintillators, solid state lasers and fluorescent bio-medicals [1]. Especially, lanthanide doped white UC luminescence has been extensively studied, because white luminescent UC phosphors have potentials to replace conventional lighting sources in optical devices and three-dimensional backlighting for colour displays. Also, white UC phosphors are expected to provide more simultaneous detections for bio-medical probes compared to conventional bio-labeling. Recently, CaMoO4 has been investigated as a potential phosphor because it has high density and more stable physical and chemical properties compared to other oxide materials. Mo6+ ions in CaMoO4 matrices have strong polarization induced by large electric charges and small radius, which leads to decrease of symmetries and enhanced stark energy splitting. Therefore, we expect that CaMoO4 can be suitable matrices for UC phosphors with high efficiency for light upconverting applications. Conventionally, solid state reaction, acid-base, precipitation, hydrothermal and sol-gel methods were used for synthesis of CaMoO4 powders. However, those methods need long processing time and steps for fabrication. Also, chemical additives in procedure may be incorporated to CaMoO4 particles as impurities, which results in bad influence to human body clinically. One novel technique for fabrication of CaMoO4 nanocrystals is pulsed laser ablation (PLA) in liquid medium. PLA of solid target in liquid has been a promising technique for producing nanocrystals for analytical and bioanalytical applications as well as the rapid synthesis of complex materials because the experimental procedure is simple and above all, chemical additive is unnecessary [2]. However, to date, there is little report on the preparation of upconverting CaMoO4:Tm3+ nanocrystals by laser ablation in liquid medium. In this study, we report a novel synthetic approach to produce CaMoO4:Tm3+ nanocrystals using PLA in liquid medium without any surfactant. The fabricated CaMoO4:Tm3+ nanocrystals were characterized in terms of their crystallinity, microstructure and upconverting property. Moreover, the laser ablation process was discussed by a thermally induced explosive ejection mechanism.
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