Visible quantum cutting through downconversion in Eu3+-doped K2GdZr(PO4)3 phosphor

K2Gd1−xZr(PO4)3:Eux3+ (0.02 ≤ x ≤ 0.1, x is in mol.%) were prepared by solid-state reaction method and their photoluminescence properties were investigated in ultra-violet (UV) and vacuum ultra-violet (VUV) region. The phenomenon of visible quantum cutting through downconversion was observed for the Gd3+–Eu3+ couple in this Eu3+-doped K2GdZr(PO4)3 system. Visible quantum cutting, the emission of two visible light photons per absorbed VUV photon, occurred upon the 186 nm excitation of Gd3+ at the 6GJ level via two-step energy transfer from Gd3+ to Eu3+ by cross-relaxation and sequential transfer of the remaining excitation energy. The results revealed that the efficiency of the energy transfer process from Gd3+ to Eu3+ in the Eu3+-doped K2GdZr(PO4)3 system could reach to 155% and K2GdZr(PO4)3:Eu3+ was effective quantum cutting material.