Blue, green, and red emission from undoped and doped ZnGa2O4 colloidal nanocrystals

Undoped, Tb(3+)- and Eu(3+)-doped ZnGa(2)O(4) colloidal nanocrystals were synthesized by a nonhydrolytic hot solution chemistry. Undoped nanocrystals exhibited an intrinsic blue emission peaking at 437 nm by self-activated transition. The emissions of Tb(3+)-and Eu(3+)-doped ZnGa(2)O(4) nanocrystals consisted of their own characteristic green and red line peaks ((5)D(4)-(7)F(j) transitions), respectively. Synthetic parameters such as activator concentration and reaction time were varied to investigate their effects on luminescent properties. Tb(3+)-doped colloidal nanocrystals synthesized for a short reaction time showed an unprecedented, exclusively green luminescence with the host blue emission effectively suppressed. On the other hand, the emission of Eu(3+)-doped ones was weak with the host emission persistently present regardless of reaction time.