Energy transfer between two luminous centers and tunable emission of La7Nb3W4O30:Dy3+, Eu3+

Abstract

New tunable-color luminescent materials with single pure phase are one of the main research objectives at present. We synthesize La7Nb3W4O30:R (LNWO:R) (RDy3+, Eu3+, and Dy3+/Eu3+) in air. The high temperature solid-state method is used. We study the purity, crystal phase and structure, luminescence properties, and lifetimes of the samples. Excitation spectrum of LNWO:Dy3+ comes from the O2− - Dy3+ charge transfer band (CTB) and the f – f electron transitions of Dy3+. LNWO:Dy3+ can glow yellow light due to the transitions 4F9/2 → 6H15/2, 6H13/2, 6H11/2, and 6H9/2 of Dy3+. LNWO:Eu3+ has excitation spectrum due to the O2− - Eu3+ CTB and the f – f electron transitions of Eu3+. LNWO:Eu3+ emits the red-orange/red light owing to the transitions 5D0 → 7F1, 7F2, 7F3, and 7F4 of Eu3+. The emitting color of LNWO:Dy3+, Eu3+ can be adjusted by changing the excitation wavelength and the content of Dy3+ and Eu3+ because of the double effects of energy transfer among Eu3+ ions and energy of Dy3+. The yellow, red-orange, and red emission of LNWO:Dy3+, Eu3+ is found. The lifetime rises with adding doped-ions concentration owing to the increase of non-radiative transitions. The luminous mechanism is analyzed via energy level diagrams. The research results offer a help for the development of new luminescent materials.