Luminescence properties of Bi³⁺ doped Lu_1-xO₃: x%Ho³⁺ metal ion phosphors

Bi³⁺ doped Lu_1-xO₃: x%Ho³⁺ metal ion phosphors were prepared using the high-temperature solid-phase method. The crystal structures of Bi³⁺ doped Lu_1-xO₃: x%Ho³⁺ phosphors, the Bi³⁺→Ho³⁺ energy transfer rule in Lu₂O₃ matrix and the luminescent properties of synthetic powders with different doping concentrations were investigated. X-ray diffraction results showed that Bi³⁺ and Ho³⁺ doping had no effect on the cubic phase structure of Lu₂O₃. Lu₂O₃: Ho³⁺, Bi³⁺ phosphor emitted ⁵S₂→⁵I₈ transition of Ho³⁺ at 551 nm under an excitation wavelength of 322 nm, and exhibited ¹S₀→³P₁ characteristic transition of Bi³⁺ at 322 nm and ⁵I₈→⁵F₁ transition of Ho³⁺ at 448 nm under an emission wavelength of 551 nm. When the doping concentration of Bi³⁺ was 1.5%, the effect was most effective for the energy transfer of Ho³⁺, which increased by a factor of 34.8 compared to that of the single-doped Ho³⁺ sample. For Lu_98.5%−yO₃:1.5%Ho³⁺, y%Bi³⁺(y=1, 1.5, 2), with the increase of Bi³⁺ ions concentration, the luminescence intensity at 551 nm under 980-nm excitation increased by a factor of 13.3, 16.8 and 14.2, respectively, compared to that of under 322-nm excitation. The energy transfer critical distance between Bi³⁺ and Ho³⁺ was calculated to be 2.979 nm, and the energy transfer between Bi³⁺ and Ho³⁺ was achieved by dipole-quadrupole interaction.