Broadband infrared luminescence from transparent glass-ceramics containing Ni²⁺-doped β -Ga₂O₃ nanocrystals

Transparent Ni²⁺-doped β-Ga₂O₃ glass-ceramics were synthesized. The nanocrystal phase in the glass-ceramics was identified to be β-Ga₂O₃ and its size was about 3.6nm. It was confirmed from the absorption spectra that the ligand environment of Ni²⁺ ions changed from the trigonal bi-pyramid fivefold sites in the as-cast glass to the octahedral sites in the glass-ceramics. The broadband infrared emission centering at 1270 nm with full width at half maximum (FWHM) of more than 250 nm was observed. The fluorescence lifetime was about 1.1 μs at room temperature. The observed infrared emission could be attributed to the ³ T _2g (³ F∈)→³ A _2g (³ F∈) transition of octahedral Ni²⁺ ions. It is suggested that the Ni²⁺-doped transparent β-Ga ₂O₃ glass-ceramics with broad bandwidth and long lifetime have a potential as a broadband amplification medium.