Intrinsic blue-white luminescence, luminescence color tunability, synthesis, structure, and polymorphism of K sub(3)YSi sub(2)O sub(7)

Two polymorphs of K sub(3)YSi sub(2)O sub(7), crystallizing in the space groups P6 sub(3)/mmc(1) and P6 sub(3)/mcm(2) can be synthesized by high temperature flux crystal growth. The flux growth conditions can be fine-tuned to yield a phase pure sample of polymorph (2), however, not of polymorph (1), which always co-crystallizes with polymorph (2). Polymorph (2) was found to exhibit intrinsic bluish-white light emission. Further studies determined that doping europium and dysprosium onto the yttrium site of this polymorph could readily tune the luminescence, with the purest white light emission found for the K sub(3)YSi sub(2)O sub(7): 10% Dy, 0.1% Eu composition (K sub(3)Y sub(0.899)Dy sub(0.1)Eu sub(0.001)Si sub(2)O sub(7)) (2-Dy,Eu).