Korean Journal of Materials Research ISSN:1225-0562(Print) 2287-7258(Online) 한국재료학회지

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.