Sr2Si5N8:Eu2+荧光粉的制备及其发光性能研究

以Sr₂CO₃、Si₃N₄和Eu₂O₃为原料, 以C为主要还原剂, 采用碳热还原氮化工艺合成Sr₂Si₅N₈:Eu²⁺荧光粉, 着重研究了C、Sr₂CO₃添加量及Eu²⁺浓度对产物物相及发光性能的影响。研究结果表明: 当C与Si₃N₄的摩尔比 n_c/=9/5时,合成出Sr₂Si₅N₈:Eu²⁺单相荧光粉, 添加适当过量的Sr₂CO₃可提高合成产物的N含量, 且荧光粉的发光强度与其N含量呈现正相关关系。在450 nm蓝光激发下, 受Eu²⁺的4f⁶5d¹ → 4f⁷跃迁作用, Sr₂Si₅N₈:Eu²⁺荧光粉在550~700 nm波段范围产生非对称宽带发射。随着Eu²⁺掺杂浓度由1.5mol%增加到20mol%, 荧光粉的发光强度先增强后减弱, 达到2mol%时发生浓度淬灭现象; 发射主峰由608 nm逐步红移至641 nm; CIE色坐标从(0.606, 0.393)位移至(0.656, 0.343), 是一种可用于白光LED的优质红色荧光粉。

Syntheses and Photoluminescence Properties of Sr2Si5N8:Eu2+ Phosphors

Sr₂Si₅N₈:Eu²⁺ phosphors were prepared by carbothermal reduction and nitridation method using Sr₂CO₃, Si₃N₄ and Eu₂O₃ as raw materials, and C as main reduction agent. The influence of C, Sr₂CO₃ and Eu²⁺ contents on phase composition and photoluminescence properties of as-prepared phosphors were investigated. The experimental results indicate that single-phase Sr₂Si₅N₈:Eu²⁺ is produced with molar ratio n_c/n_Si3N4=9/5. Excessive Sr₂CO₃ addition contributes to the N contents of the as-prepared phosphors, which enhances emission intensity. There is an asymmetric wide emission peaks between 550 nm and 700 nm due to the electron transfer of Eu²⁺ from 4f⁶5d¹ to 4f⁷ excited by 450 nm. Increasing Eu²⁺ concentration from 1.5mol% to 20mol%, the luminescence intensity hits the maximum value at Eu²⁺ concentration of 2mol% followed by continuous decline. Meanwhile the emission peak position is red-shifted from 608 nm to 641 nm, and the CIE chromaticity coordinates varies from (0.606, 0.393) to (0.656, 0.343), which indicates that Sr₂Si₅N₈:Eu²⁺ is a promising phosphor for white LEDs.