White emitting 5ZnO-(5–2.5x)Ga2O3- 2.5xAl2O3–90SiO2 glass ceramic embedded with Mn doped Zn(Ga,Al)2O4 nanocrystals

Abstract

Dual-emitting manganese ions singly doped 5ZnO-(5–2.5x)Ga 2 O 3 -2.5 xAl 2 O 3 –90SiO 2 glass-ceramic (GCs) samples, containing the alloyed Zn(Ga, Al) 2 O 4 nanocrystals with a size of about 5 nm, were successfully prepared by a sol-gel method under different heat treatment temperatures, demonstrating an excellent white light emission. We found that the formation of the ZnGa 2 O 4 nanocrystals began at 650 °C (absence of Al 2 O 3 , x = 0) while that of the ZnAl 2 O 4 crystals required a higher temperature of about 900 °C (presence of Al 2 O 3 , x = 2) in SiO 2 glasses. A nanostructured Zn(Ga, Al) 2 O 4 :Mn 2+ , Mn 4+ in the glass-ceramic was synthesized by Al 3+ replacing part of Ga 3+ . The doping of Al 3+ has effectively contributed to the existence of Mn 2+ , thus realizing the regulation of the valence state of manganese ions. The glass ceramic samples showed red emission arrived from the 2E g → 4A 2g transitions of Mn 4+ , green emission originated from the 4T 1 →6A 1 transition of Mn 2+ , and blue emission derived from the self-activation center of ZnGa 2 O 4 nanocrystalline. In particular, the 0.1%Mn doped the 5ZnO-(5–2.5x)Ga 2 O 3 -2.5xAl 2 O 3 –90SiO 2 glass-ceramic samples can provide white color emission depending on the Al doping concentration (x), x = 0.4–0.9 and the annealing temperature, 650–900 °C.