“…In many cases, the Bi 3+ ion also can be used as an efficient sensitizer for the RE or non-RE [290], Sm 3+ [291][292], 3d Mn 4+ [293][294][295][296], and Cr 3+ ions [189,297]), and multiple RE/non-RE co-dopants [288,[298][299][300][301] to improve or influence the fluorescent properties of these co-dopants. Sometimes, the Bi 3+ can spread the persistent potentialities toward the short wavelength region, allowing the persistent range being broader than that with single RE and TM dopant.…”