Interstitial Site Engineering for Creating Unusual Red Emission in La<sub>3</sub>Si<sub>6</sub>N<sub>11</sub>:Ce<sup>3+</sup>
Shihai You, Shuxing Li, Yongchao Jia, Rong‐Jun Xie
Abstract
Traditionally, phosphors are developed by doping activators on standard crystallographic sites of selected inorganic hosts, thus enabling the prediction of their luminescence with some empirical models or theoretical calculations. Here, we propose the idea of interstitial site engineering as a totally different way to design phosphors with promising properties. In detail, a red-emitting phosphor La3Si6N11:Ce3+,Al3+ was developed by engineering the interstitial Ce3+ site, which produces an unusual red emission band (λem = 600–665 nm) under blue light excitation. The origin of this red emission was assigned from the first-principle calculation to the Ce3+ ion occupying the [Si8N8] void in the c∼1/2 layer of which the calculated transition energies matching with experiment within 0.1 eV. Such an interstitial Ce3+ site was created as a charge compensator for the aliovalent substitution of Si4+ by Al3+ ions. The red-enhanced La3Si6N11:Ce3+,Al3+ phosphor showed great potentials for improving the optical quality (i.e., color temperature and color rendition) of laser-driven white light. This work indicates that the interstitial site engineering is an efficient way for generating new luminescence centers and opens up an avenue for designing phosphors with appealing properties.