Sm3+-activated gadolinium molybdate: an intense red-emitting phosphor for solid-state lighting based on InGaN LEDs

Sm3+-activated gadolinium molybdate, Gd2(MoO4)3:Sm3+ red-emitting phosphor was prepared by conventional solid-state method. The structure, morphology, and luminescent properties of these powder samples have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and fluorescent spectrophotometry, respectively. The as-obtained phosphor has a monoclinic structure with single crystalline phase. Its mean particle size is about 6–8 μm with pseudo-pompon shape and large surface area, which is suitable for manufacture of white LEDs. The phosphor can be efficiently excited by incident light of 348–445 nm, well matched with the output wavelength of a near-UV InGaN-based chip, and re-emits an intense red light peaking at 650 nm. By combing this phosphor with a 405 nm-emitting InGaN chip, a red LED was fabricated, so that the applicability of this novel phosphor to white LEDs was confirmed. It is considered to be an efficient red-emitting conversion phosphor for solid-state lighting based on InGaN LEDs.