Controlling the color with different excitations in a dysprosium-activated apatite oxynitride phosphor

Abstract

Among the f-f transition of lanthanide ions, trivalent dysprosium (Dy3+) activated luminescence materials always exhibit polychromatic emission with different ratios of blue to yellow emission (B/Y ratio), which originates from the two main transitions 4F9/2 to 6H15/2 and 6H13/2, respectively. Researchers have found the B/Y ratio is dependent on the host structure. Meanwhile, Dy3+-activated luminescence materials have various applications under different excitations. However, the relationship between them (excitation vs emission color) has not been studied yet, which restricts the development of fundamental research and applications. In this study, we reported an excitation-controlled color variation material, the apatite oxynitride phosphor Y5Si3O12N: Dy3+ and investigated the color-reversal phenomenon by switching excitation sources (from UV to VUV or cathode ray) in the material. This phenomenon is unraveled by a defect-assisted charge carrier transport model that the defect could change the chemical surrounding of Dy3+ and result in the blue emission dominant instead of the initial yellow emission. The mechanism is evidenced by the crystal structure analysis, luminescence properties dissect, defects state parse, etc. This study also provides new insights to understand and modulate Dy3+-activated luminescence materials.