Synthesis and Upconversion Luminescence Properties of BaIn₆Y₂O₁₃:Yb³⁺, Er³⁺

BaIn₆Y₂O₁₃ phosphors with different doping concentrations of Yb³⁺ and Er³⁺ were prepared via the high temperature solid-state reaction method. XRD data showed that BaIn₆Y₂O₁₃ phosphors belong to hexagonal system and the introduction of doping agent Yb³⁺ and Er³⁺ did not change the lattice structure of the host. The upconversion emission spectrum and power were measured by 971 nm LD laser with different excitation powers and the energy efficiencies of the samples were calculated. The obtained data showed that the ratio of green power to red power kept decreasing with the increase in doping agent concentration when the excitation density remains constant, increasing with the increase in the excitation density at the same concentration of doping agent. The analyses revealed that the former was attributed to the increasing cross relaxation between Er³⁺ ions, while the latter came from the raise of the energy transfer between Yb³⁺ and Er³⁺ ions and the excited state absorption of Er³⁺ ions due to the higher excitation density. With the increase in the excitation density, at the beginning the green luminescence power was proportional to the square of the excitation power, which agrees with the reported result. The maximum values of the fluorescence efficiencies of the samples were obtained as 0.38% (the doping concentrations of Yb³⁺ and Er³⁺ are 3%, 1%)and 0.06%(the doping concentrations of Yb³⁺ and Er³⁺ are 9%, 3%). It can be attributed to the long lifetime of ⁴ I _13/2 energy level so it can gather a large number of electrons and reduce the population of ground state, resulting in lower pump efficiency.