LuNbO4:0.2Yb3+,xTm3+ powders were prepared using a solid-state reaction process. The effects of the amount of Tm on up-conversion(UC) and down-conversion(DC) luminescence properties are investigated. X-ray diffraction patterns confirm that Yb3+ and Tm3+ ions are successfully incorporated into Lu sites. Under 980 nm excitation, the UC spectra of the powders predominantly exhibit strong near-infrared emission bands that peak at 805 nm, whereas weak 480 nm emission bands are observed as well. The emission bands are assigned to the 1G4→ 3H6 (480 nm) and 3H4→ 3H6 (805 nm) transitions of the Tm3+ ions via an energy transfer from Yb3+ to Tm3+; two- and three-photon UC processes are responsible for the 805 and 480 nm emissions, respectively. The DC emission spectra exhibit blue emission (1D2→ 3F4) of Tm3+ at 458 nm. The amount of Tm affects the emission intensity with the strongest emissions at x = 0.007 and 0.02 for the UC and DC luminescence, respectively. The results demonstrate that LuNbO4:Yb3+,Tm3+ phosphors are suitable for bio-applications.

Abstract
 1. 서 론
 2. 실험 방법
 3. 결과 및 고찰
 4. 결 론
 References

• 임민혁(경기대학교 신소재공학과) | Min Hyuk Im (Department of Advanced Materials Engineering, Kyonggi University)
• 김영진(경기대학교 신소재공학과) | Young Jin Kim (Department of Advanced Materials Engineering, Kyonggi University) Corresponding author