Investigation on Energy Transfer and Luminescent Properties of K 3 Gd(PO 4 ) 2 :RE 3+ (RE = Eu, Tb) Under UV and VUV Excitation

K 3 Gd ( PO 4 ) 2 : RE 3+ (RE = Eu, Tb) are prepared by solid‐state reaction and their photoluminescence ( PL ) properties are investigated under UV and VUV excitation, respectively. The obtained experimental data show that no energy transfer happens among the activator ions Tb 3+ or Eu 3+ under UV excitation. Under 147‐nm excitation, the strongest emission intensity of K 3 Gd ( PO 4 ) 2 : RE 3+ (RE = Eu, Tb) is obtained when the activator ions Tb 3+ or Eu 3+ concentration is 0.8 mol, the integrate emission intensity of K 3 Gd 0.2 (PO 4 ) 2 :0.8Tb 3+ is about 204% of commercial phosphor Zn 1.96 SiO 4 :0.04 Mn 2+ with chromaticity coordinates of (0.340, 0.561) and the decay time of about 5.09 ms under 147‐nm excitation. We analyze the experimental data and propose a possible energy‐transfer mechanism under 147‐nm excitation.