Energy transfer, luminescence properties, and thermal stability of color tunable barium pyrophosphate phosphors

A series of barium pyrophosphate Ba₂P₂O₇ (BPO) phosphors doped with Ce³⁺ or Tb³⁺ ions is synthesized via a co-precipitation method under reducing atmosphere. The phase structures, photoluminescence (PL) properties, and thermal stabilities of the samples are characterized by using powder x-ray diffraction (PXRD) and PL spectra. The emission colors of samples can be tuned from blue (0.1544, 0.0310) to green (0.2302, 0.4229) by changing the doping concentrations of Tb³⁺ under ultraviolet excitation. The energy transfer mechanism between Ce³⁺ and Tb³⁺ in the BPO is dipole-dipole interaction with a critical distance of 25.86 Å and an energy transfer efficiency of about 85%, which are determined through the PL spectrum and the decay curve. Moreover, the Ce³⁺/Tb³⁺ co-doped sample has good thermal stability for temperature quenching, and the emission intensity at 423 K is maintained at 95% measured at 298 K. The above results show that the BPO:Ce³⁺, Tb³⁺ can serve as a promising candidate of green emitting phosphor for solid-state lighting.