Design of a nitridoalumosilicate red phosphor synthesized under mild conditions.

Developing nitridosilicate red phosphors under mild synthesis conditions is important for regulating the emission quality of white light-emitting diodes (WLEDs). Based on the thermodynamic theory and crystal structure chemistry for the synthesis of nitridosilicates, the Gibbs free energy variation of a hybrid system can be made more negative by reducing the proportion of Si3N4 and increasing the proportion of M2N3 and AlN, enabling the formation of new nitridosilicates under mild conditions. Therefore, a general chemical formula MxSiyAlzNk was proposed for the design of nitridosilicate red phosphors prepared under mild conditions, where M is an alkaline earth metal ion; x > y; z ≥ y; 1 ≤ y ≤ 3; x + 2y = 3n + 3; k - z = 2n + 2; and n is a positive integer. Therefore, in this study, we successfully synthesized the nitridoalumosilicate red phosphor Ca4SiAl3N7:Eu2+ at normal pressure and lower temperature (1350 °C). Under excitation with 460 nm blue light, the Ca4SiAl3N7:Eu2+ phosphor efficiently emits red light at 645 nm and exhibits excellent thermal stability. The crystal structure and luminescence properties of Ca4SiAl3N7:Eu2+ were investigated in detail. The results indicate that Ca4SiAl3N7:Eu2+ exhibits strong potential for use in WLEDs. The design of nitridoalumosilicate red phosphors synthesized under mild conditions based on Gibbs free energy variation provides a new idea for the development of new nitride phosphors.