The up-conversion properties of Yb ~3 and Er ~3 doped Y _4Al _2O _9 phosphors

摘要

Er ~3 doped and Yb ~3/Er ~3 co-doped Y _4Al _2O _9 phosphors are prepared by the solgel method. The effect of dopant concentration on the structure and up-conversion properties is investigated by X-ray diffraction (XRD) and photoluminescence, respectively. XRD pattern indicates that the sample structure belongs to monoclinic. Under 980 nm excitation, the green and red up-conversion emissions are observed and the emission intensities depended on the Yb ~3 ion concentration. The green up-conversion emissions decrease with the increase of Yb ~3 concentration, while red emission increases as Yb ~3 concentration increases from 0 to 8 at% and then decreases at high Yb ~3 concentration. The mechanisms of the up-conversion emissions are discussed and results shows that in Er ~3 and Yb ~3/Er ~3 co-doped system, cross-relaxation (CR) and energy transfer (ET) processes play an important role for the green and red up-conversion emissions.