Broadly tunable emission from Ca2Al2SiO7:Bi phosphors based on crystal field modulation around Bi ions
New non-rare-earth activated phosphors were discovered and have attracted much attention in the field of energy-efficient LED lighting. For instance Bi3+, when mixed into different matrix materials, can realize multiple luminescence intensities ranging from 400 to 700 nm. The tunable emission results from the susceptibility of bismuth naked 6s electrons to the crystal field surrounding Bi3+. In this work, we report the broadly adjustable emission of Bi3+ doped Ca2Al2SiO7 phosphors by modifying the local environment around Bi3+. When M+ (M = Li, Na and K) is incorporated into the Ca2Al2SiO7 lattice, the luminescence intensity is improved greatly. In addition, the position of the emission peak of Bi3+ shifts from 382 to 416 nm upon varying the relative ratio of B3+/Al3+/Ga3+ ions. The spectral red-shift behaviour is attributed to the enhancement of crystal field strength surrounding Bi3+. These results are promising for investigation of the luminescence properties of Bi3+.