Evolution of Structure and Photoluminescence by Cation Cosubstitution in Eu2+-Doped (Ca1–xLix)(Al1–xSi1+x)N3 Solid Solutions

Inorg. Chem. 2016, 55, 6, 2929–2933

Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitting diodes (WLEDs). Chemical composition and structural modification are generally adopted to optimize the photoluminescence behaviors of the targeted phosphors. Herein, on the basis of the famous CaAlSiN3 phosphors, Eu2+-doped (Ca1–xLix)(Al1–xSi1+x)N3 solid solutions via the cations’ cosubstitution of (CaAl)5+ pair by (LiSi)5+ pair are successfully synthesized by a solid state reaction, and the lattice parameters show a linear decrease with chemical compositions suggesting the formation of the isostructural phase relationship. Four types of coordinated structure models, corresponding to different coordination environments of Eu2+, are proposed over the course of structural evolution, which induces different structural rigidity and stability, and then they are responsible for three-stage changes of emission spectra of Eu2+ in (Ca1–xLix)(Al1–xSi1+x)N3 solid solution.