Novel rare earth activator ions-doped perovskite-type La4Ti3O12 phosphors: Facile synthesis, structure, multicolor emissions, and potential applications

Abstract

A series of novel rare earth activator ions-doped perovskite-type lanthanum titanate La4Ti3O12 phosphors have been synthesized via the Pechini sol-gel method. The influence of calcination temperature and time on crystal structure of the La4Ti3O12 matrix is investigated, and the result indicates that higher temperature and longer calcination time is beneficial for better crystallinity. Upon ultraviolet excitation, the as-synthesized activator ions (Dy3+, Eu3+, Sm3+, and Tb3+) ions doped La4Ti3O12 phosphors display the characteristic quasi-white, reddish orange, orange, and green emissions in visible region. The higher calcination temperature and longer time can induce stronger luminescence due to enhanced crystallinity of La4Ti3O12 host. The optimal doping concentrations of Dy3+, Eu3+, Sm3+, and Tb3+ ions are determined to be 2, 12, 2, and 10 mol%, respectively. The corresponding LED devices fabricated by the phosphors and UV LED chips can exhibit bright characteristic multicolor emissions of activator ions, indicating their potential in LEDs and optoelectronic devices. Moreover, the up-conversion luminescence properties of the Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+ doped samples are also studied. The result shows that the excellent up-conversion performances can be also realized by doping appropriate rare earth ions into the host matrix by employing the NIR excitation. It is anticipated that this work may be of significance for the design and preparation of perovskite-type rare earth luminescent materials.