Multicolour emission from thermally stable Tb3+/Eu3+ co-doped CaLa4Si3O13 phosphors for single-component w-LEDs application

Abstract

Colour-tuneable Tb3+/Eu3+ co-doped CaLa4Si3O13 phosphors were prepared by a high-temperature solid-state reaction approach. The contraction of unit cell volume was concluded from the XRD Rietveld refinements data after introduction of dopants and suggests that the dopants have been effectively incorporated into the La3+ sites. Characteristic emission peaks at 545 and 617 nm originated from Tb3+ and Eu3+ emitting centres are observed under the excitation of 379 nm light. An adjustment of emission colour is achieved by varying the Eu3+ concentration. Energy transfer from Tb3+ to Eu3+ ions is experimentally confirmed from the photoluminescence and lifetime measurements. The dipole-dipole interaction is proposed as the main energy transfer route by Dexter's energy transfer formula and Inokuti-Hirayama model. The prepared phosphors exhibit good thermal stability at elevated temperatures. The results indicate that the synthesized materials have a great potential for single-component w-LED applications.