Structure modification and covalence variation induced by cation substitution in pure nitride Ca-α-sialon phosphor

•Owe to the increase of crystallinity with Al3+ incorporating, the photoluminescent intensity of the phosphors increased by 49%.•The modified structure results in a strong covalence of Eu-N and improved the thermal quenching behavior.•The stronger covalent coordination environment for Eu2+ lead to a red-shift of the emission.

Cation substitution is a useful method to modify the structure and luminescence properties of nitridosilicate phosphors. The crystal structure of pure nitride Ca-α-sialon with the composition Ca1.3+0.5xAl2.8+xSi9.2−xN16:Eu0.1 is changed by cation substitution (Al3+ → Si4+). Smooth changes of lattice parameters with x indicate that Al3+ ions have been effectively incorporated into the Ca1.4Al2.8Si9.2N16 lattice. Although the replacement of Si4+ by Al3+ expands the lattice volume, the covalent coordination environment for Eu2+ becomes stronger. Eventually, the emission exhibits a red-shift. Owing to the increase of the crystallinity with Al3+ introducing, the emission intensity of the phosphors increases by 49%. The modified structure results in a strong covalence of Eu-N and an improvement of the thermal quenching.

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