Energy transfer and luminescence properties of Dy3+ ions doped in La2W3O12 lattices

Abstract

La2W3O12:Dy3+ phosphors were synthesized by using a high-temperature solid-state reaction. The Dy3+ concentration in the La2W3O12 lattice was varied from 0.01 to 100 %. The crystalline phases of the samples were confirmed by using an X-ray diffraction analyses. Emission and excitation spectra and decay curves of Dy3+ ions in the La2W3O12 lattices were measured at room temperature. The two charge-transfer (CT) bands that overlapped in the wavelength region 210 - 320 nm were identified as being due to the CT transitions of O2−-Dy3+ and WO 4 2− . The decay times of the 4F9/2 emission were shortened with increasing Dy3+ concentration, and the decay curves were slightly nonexponential even at low Dy3+ concentration. The decay curves were well fitted by the Inokuti-Harayama model based on the energy-transfer process between two Dy3+ ions at concentrations lower than 10 mol%. On the other hand, the energy diffusion among Dy3+ ions dominate the energy-transfer process at higher Dy3+ concentrations up to 100 mol%.