Modification of the crystal structure of Sr2-xBaxSi(O,N)(4): Eu2+ phosphors to improve their luminescence properties
Modification of the crystal structure of Sr2-xBaxSi(O,N)(4): Eu2+ phosphors to improve their luminescence properties
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修饰Sr2-xBaxSi(O,N)(4)：Eu2荧光粉的晶体结构以改善其发光性能
DOI：
10.1039/c5ce01605c
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发表时间：
2015
期刊：
影响因子：
3.1
通讯作者：
Xu Shiqing
中科院分区：
文献类型：
--
作者：
Li Xiaojun;Hua Youjie;Ma Hongping;Deng Degang;Xu Shiqing
采用固相反应法制备了一系列Sr1.98−xBaxSi(O，N)4：0.02Eu2+(0≤x≤0.5)荧光粉。在FT-IR谱中可以观察到Sr-N键和Si-N键。X-射线衍射分析结果表明，在形成Sr1.98Si(O，N)_4：Eu~(2+)(SSON：Eu~(2+))置换固溶体的过程中，N3-−取代了O_(22)−，形成了Si-NO_3四面体。−：Eu2+的晶格常数随Ba-O键长的增加而增大，这是由于Eu-N键的共价键效应较强而产生的云延伸效应和强的晶场分裂所致。Ba2+掺杂前，SSON：Eu2+具有β相结构，而α‘-SbSON相是通过Ba2+取代Sr2+得到的。在375 nm和460 nm激发下，Ba2+掺杂引起了明显的蓝移。Ba2+的5d轨道与Eu2+的5d轨道在主体晶体的较高能级位置上耦合。在375 nm激发下，随着Ba2+含量的增加，发光强度逐渐增强。在460 nm激发下，随着Ba2+含量的增加，发光强度逐渐减弱。与α-SsoN：Eu2+和β-SsoN：Eu2+相比，β‘-SbSON：Eu2+的热稳定性显著提高。基于它们的发射波长可调、发光强度增强以及在SBSON：Eu2+中良好的热稳定性，我们预计这些材料可以用作白光发光二极管的绿色或红色荧光粉。
A series of Sr1.98−xBaxSi(O,N)4: 0.02Eu2+ (0 ≤ x ≤ 0.5) phosphors were synthesized by a conventional solid state reaction method. The Sr–N and Si–N bonds could be observed in FT-IR spectra. The XRD refinement results indicated that N3− would substitute for O22− and form Si–NO3 tetrahedrons during the process of forming the Sr1.98Si(O,N)4: Eu2+ (SSON: Eu2+) substitutional solid solution. The lattice constants of Sr1.98−xBaxSi(O,N)4: 0.02Eu2+ (SBSON) were increased due to the longer bond length of Ba–O. Compared with Sr2SiO4: Eu2+, the SSON: Eu2+ showed a remarkable red-shift, which is due to the nephelauxetic effect and the strong crystal field splitting originating from the stronger covalent bonding effect of the Eu–N bond. The SSON: Eu2+ presented a β phase structure before the introduction of Ba2+, whereas the α′-SBSON phase was obtained by the substitution of Ba2+ for Sr2+. Ba2+ doping led to an obvious blue-shift under 375 nm and 460 nm excitation. The 5d orbital of Ba2+ is coupled with the 5d orbital of Eu2+ on the higher energy level position in the host crystal. Under 375 nm excitation, the PL intensity gradually increased with the increase of the Ba2+ content. Under 460 nm excitation, the PL intensity gradually declined with the increase of Ba2+ content. The thermostability of α′-SBSON: Eu2+ was significantly improved compared with β-SSO: Eu2+ and β-SSON: Eu2+. On the basis of their adjustable emission wavelength, enhanced PL intensity and excellent thermostability in SBSON: Eu2+, we anticipate that these materials can be used as green or red phosphors in white light emitting diodes.