Structural Micromodulation on Bi3+-Doped Ba2Ga2GeO7 Phosphor with Considerable Tunability of the Defect-Oriented Optical Properties

We report a new Ba2Ga2GeO7:Bi3+ phosphor with broad emission almost covers the entire visible area generated from different bismuth emission centers in crystalline structure. The two peaks’ positions are invariably located at 497 and 611 nm which were independently excited by 365 and 387 nm excitation sources. As the emission tightly relies on the excitation source in an extremely wide range (260–470 nm), the emission color can be easily manipulated from cyan to red. The WLEDs devices with Ra = 90.40 and 91.98 were fabricated by employing Ba2Ga2GeO7:0.012Bi3+ as a red component phosphor. Through analyzing, we found P2 (Ga/Ge) sites tend to form vacancies in the sintering process. When bismuth concentration is set fixed, the luminescent intensity is quite dependent on the quantity of Ga or Ge vacancies which are beneficial to form Bi3+ emission centers and provide a fresh idea for structural micromodulation. Our results also provide new insights for understanding the roles of the vacancy played in phosphors.