Novel Self‐Activated Zinc Gallogermanate Phosphor: The Origin of its Photoluminescence

Since 2012, zinc gallogermanate has drawn interests as an excellent host phosphor for a variety of dopants (e.g., Cr 3+ , Bi 3+ and Mn 2+ ). However, the origin of its self‐activated luminescence has been largely unknown. Here, zinc gallogermanate of the composition Zn 1+ x Ga 2−2 x Ge x O 4 (0 ≤ x ≤ 1) is prepared by solid‐state reaction, and the evolution of the crystal structure with the composition is studied. The phosphors show a broad white‐bluish emission upon excitation by ultraviolet (UV) light, and the luminescence intensity greatly increases as Ga 3+ are substituted by Ge 4+ . A full spectrum of the defects and trap centers responsible for the luminescence is given by a multiple characterization methods, such as low temperature electron spin resonance, positron annihilation lifetime and thermoluminescence spectra. The results show that the zinc gallogermanate is a promising self‐activated phosphor for a variety of applications.