Photochromism and emission-color change in Ba3MgSi2O8-based phosphors

Eu2+-doped Ba3MgSi2O8 phosphor, prepared by high-temperature solid state reaction in a reducing atmosphere, shows a blue emission under ultraviolet light excitation. When this phosphor is exposed to Xe-lamp radiation, the colorless powder turns orange, and the emission color changes to purple. The Xe-lamp induced orange color is successfully bleached by heat treatment at 350 °C for 30 min. Then, the emission color also returned to the original blue. The observed photochromic behaviors can be explained by electron transition in Eu2+-associated FA centers.