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

Bi ³⁺doped Lu _1-xO ₃: x%Ho ³⁺metal ion phosphors were prepared using the high-temperature solid-phase method. The crystal structures of Bi ³⁺doped Lu _1-xO ₃: x%Ho ³⁺phosphors, the Bi ³⁺→Ho ³⁺energy transfer rule in Lu ₂O ₃matrix and the luminescent properties of synthetic powders with different doping concentrations were investigated. X-ray diffraction results showed that Bi ³⁺and Ho ³⁺doping had no effect on the cubic phase structure of Lu ₂O ₃. Lu ₂O ₃: Ho ³⁺, Bi ³⁺phosphor emitted ⁵S ₂→ ⁵I ₈transition of Ho ³⁺at 551 nm under an excitation wavelength of 322 nm, and exhibited ¹S ₀→ ³P ₁characteristic transition of Bi ³⁺at 322 nm and ⁵I ₈→ ⁵F ₁transition of Ho ³⁺at 448 nm under an emission wavelength of 551 nm. When the doping concentration of Bi ³⁺was 1.5%, the effect was most effective for the energy transfer of Ho ³⁺, which increased by a factor of 34.8 compared to that of the single-doped Ho ³⁺sample. For Lu _98.5%−yO ₃:1.5%Ho ³⁺, y%Bi ³⁺( y=1, 1.5, 2), with the increase of Bi ³⁺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 Bi ³⁺and Ho ³⁺was calculated to be 2.979 nm, and the energy transfer between Bi ³⁺and Ho ³⁺was achieved by dipole-quadrupole interaction.