Evidence for visible quantum cutting via energy transfer in SrAl12O19:Pr,Cr.

Evidence for visible quantum cutting involving the emission of two visible photons for each vacuum-ultraviolet (VUV) photon absorbed is demonstrated in SrAl(12)O(19):Pr,Cr using synchrotron radiation as one of the excitation sources. Upon VUV excitation of the 4f5d states of Pr(3+), quantum cutting could occur by a two-step energy transfer from Pr(3+) to Cr(3+) by cross relaxation and sequential transfer of the remaining excitation energy. A theoretical visible quantum efficiency of 147% is estimated in SrAl(12)O(19):2% Pr,5% Cr, suggesting the possibility of a VUV phosphor with visible quantum efficiency higher than 100% based on Pr(3+)-Cr(3+) pair in oxide materials.