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 vacuumultraviolet (VUV) photon absorbed is demonstrated in SrAl₁₂O₁₉:Pr, Cr using synchrotron radiation as one of the excitation sources. Upon VUV excitation of the 4f5d states of Pr³⁺, quantum cutting could occur by a two-step energy transfer from Pr³⁺ to Cr³⁺ by cross relaxation and sequential transfer of the remaining excitation energy. A theoretical visible quantum efficiency of 147% is estimated in SrAl₁₂O₁₉:2% Pr,5% Cr, suggesting the possibility of a VUV phosphor with visible quantum efficiency higher than 100% based on Pr³⁺–Cr³⁺ pair in oxide materials.