Influence of Impurities on the Luminescence Quantum Efficiency of the Lamp Phosphor ( Ce , Gd , Tb ) MgB5 O 10

Abstract

The influence of impurities on the luminescence quantum efficiency of has been studied. Low concentrations of Pr³⁺, Nd³⁺, Dy³⁺, Ho³⁺, and Er³⁺ do not compete efficiently with Gd³⁺ and Tb³⁺ for the excitation energy on the Ce³⁺ ions. However, the luminescence efficiency of Ce³⁺ is strongly decreased by Sm³⁺ and Eu³⁺ due to an electron transfer process. The luminescence efficiency of Ce³⁺ is also decreased by Cr²⁺, Mn²⁺, Fe²⁺, and Ni²⁺ due to energy transfer to these ions. In the case of Cr³⁺ the luminescence efficiency of Ce³⁺ is quenched due to competitive absorption. The luminescence efficiency of Gd³⁺ is strongly decreased by Cr²⁺, Mn²⁺, and Fe²⁺ due to energy transfer to these ions. The excitation energy migrates over the Gd³⁺ ions. Therefore, low concentrations of impurities have a considerable effect on the luminescence efficiency of Gd³⁺. Since there is no energy migration over the Tb³⁺ ions, small concentrations of impurities have a limited effect on the luminescence efficiency of Tb³⁺.