Structural influence on photochromic behaviors of Eu2+-doped glaserite-type silicates

Ba2.98-xSrxEu0.02MgSi2O8 (x ≤ 0.365) exhibited emission-color change when exposed to the light from a Xe arc-lamp. Blue emission observed from the above phosphors turned purple after the photostimulation because of 608-nm emission centers arising. The degree of the spectral change monotonically decreased with increasing Sr-replacement x, and became undetectable when x exceeded 0.490. This x value coincided with that dividing the structural symmetry between P3¯ (Z = 3) and P3¯m1 (Z = 1). This coincidence indicates that structural distortion caused by B-site Ba2+ ions contributes to the photostimulated emission-color change of the Eu2+-doped glaserite-type alkali-earth magnesium silicates.