Quantum cutting effect inKY3F10:Tm3+

Abstract

A cross-relaxation energy-transfer scheme using the 5d state of Tm 3+ as the donor and the 4f 13 states of Tm 3+ as the acceptor is proposed. The scheme is tested in the host KY 3 F 10 doped with several concentrations of Tm 3+ as a potential vacuum ultraviolet ͑VUV͒ excited blue phosphor of quantum yield greater than unity. Emission and diffuse reflection spectra along with studies of the time evolution of the 5d and 4f populations of Tm 3+ in KY 3 F 10 crystals and powders under UV and VUV excitations are reported and analyzed. The results show that the proposed quantum cutting mechanism occurs but the 1 I 6 , 1 D 2 , and 1 G 4 acceptor levels cross relax rapidly to lower-lying levels by an additional cross-relaxation energy transfer and that this effectively quenches the blue emission. Based on the temperature dependence of the spectra, an interesting heat-assisted relaxation process involving intersystem crossing is observed above 300 K.

Energy transfers between Sm3+ and Eu3+ in YPO4, LaP5O14 and LaP3O9 phosphates. Potential quantum cutters for red emitting phosphors

“…In LaP 3 O 9 and LaP 5 O 14 no red emission was detected under excitation at high energy below 150 nm although the absorption was very strong. No VUV emission was detected either, like in the case of KY 3 F 10 :Tm 3+ [26]. This is a very unusual behavior which was already observed [27].…”

Lanthanide 4f energy levels in perovskite-type YAlO3

“…Actually, it was reported that YF 3 :Pr 3 þ shows 4f-4f emission from 1 S 0 [38,39]. In Nd 3 þ and Tm 3 þ doped YAlO 3 , many luminescence peaks were observed by various 4f-4f transitions [40][41][42][43][44][45][46][47]. Some UV luminescence peaks in the Nd 3 þ and Tm 3 þ samples were observed mainly from the emission levels of 2 G(2) 9/2 and 3 P 0, respectively.…”

Energy levels and crystal-field analysis of Tm3+ in YAl3(BO3)4 crystals

“…Micro-or nano-sized powders containing Tm 3 þ alone [4,5] or in combination with other rare earth ions [6,7] are interesting materials for developing blue and white phosphors. In this connection it has to be pointed out the recent and continuously growing interest towards Tm 3 þ -based phosphors with quantum yield greater than 1 to be used in plasma display panels (PDPs) and mercury-free fluorescent lamps [8]. These materials operate by a process called quantum cutting (QC) and require large bandgap host lattices suitable for UV and VUV excitations [9].…”