Novel powellite-based red-emitting phosphors: CaLa1−xNbMoO8:xEu for white light emitting diodes

We report the photoluminescence properties of a novel powellite-based red-emitting phosphor material: CaLa_1−xNbMoO₈:xEu³⁺ (0.01, 0.03, 0.05, 0.1) for the first time. The photoluminescence investigations indicated that CaLa_1−xNbMoO₈:xEu³⁺ emits strong red light at 615 nm originating from ⁵D₀→⁷F₂ (electric dipole transition) under excitation either into the ⁵L₀ state with 394 nm or the ⁵D₂ state with 464 nm, that correspond to the two popular emission lines from near-UV and blue LED chips, respectively. When compared with emission intensity from a CaMoO₄:Eu³⁺, the emission from CaLaNbMoO₈:Eu³⁺ showed greater intensity values under the same excitation wavelength (394 nm). The enhanced red emission is attributed to the enhanced f-f absorption of Eu³⁺. These materials could be promising red phosphors for use in generating white light in phosphor-converted white light emitting diodes (WLEDs).