Tunable luminescent Eu2+-doped dicalcium silicate polymorphs regulated by crystal engineering

In this work, tunable luminescence of dicalcium silicate doped with Eu2+ ions is demonstrated based on crystal engineering. Five types of dicalcium silicate polymorphs (γ-, β-, αL′-, αH′-, α-Ca2SiO4) are synthesized by incorporating a crystal-phase stabilizer (CPS), in order to afford variable accommodation frameworks for the Eu2+ activator. Tunable luminescence is observed as the polymorph transforms from one crystal form into another. In addition, the luminescence of Eu2+ in peculiar crystal-phase Ca2SiO4 hosts is further customized by crystal-site engineering, which regulates the coordination environment of Eu2+ in multiple types of Ca2+ sites. The luminescence properties of our Eu2+-doped dicalcium silicate polymorphs show promising prospects for LED lighting applications.