稀土Y_(2-x)SiO_5∶Eu_x^(3+)纳米发光材料结构对发光性能影响及发光机理研究

Nano Y_(2-x)SiO_5:Eu_x^(3+):Preparation,Structure Effect on Emitting Properties,Emitting Mechanism

用溶胶凝胶法合成了Y2-xSiO5∶Eux纳米发光材料,使用XRD、FTIR和TEM对其结构进行了表征。讨论了相结构、煅烧温度和Eu3+掺杂浓度对材料发光性能的影响及规律。结果显示煅烧温度在900℃以下,材料主要呈非晶相结构,900℃以上材料主要呈晶态结构;颗粒随煅烧温度升高而增大,在非晶态时颗粒大小在15~45nm,在晶态时颗粒大小为60~80nm。激发光谱和荧光发射光谱受材料晶相结构以及Eu3+掺杂浓度的影响,在晶态结构中Y2-xSiO5∶Eux纳米材料呈现更精细的激发和发射光谱。在激发光谱中,电荷转移态吸收(CST)随煅烧温度升高呈现兰移现象,晶态时CST同非晶态相比明显红移;在发射光谱中,非晶态时5D0→7F2跃迁呈现强的发光峰,随材料制备温度升高而增强,在晶态时该发光峰强度减弱,在长波波段呈现两个新的发光尖峰,并随煅烧温度升高而增强;5D0→7F1发射峰从非晶态转变为晶态后,光谱裂分为三重尖峰;而5D0→7F0跃迁发光光谱受结构和颗粒大小影响较小。同时在60~80nm的Y2-xSiO5∶Eux晶体中,发现材料5D0→7F2和5D0→7F1跃迁发光强度,均受Eu3+掺杂浓度的影响,当掺杂浓度x=0.4时,材料发光强度最大。

Nano-meter Y2-xSiO5：Eux, materials were synthesized by sol-gel method, and its structure and morphology were characterized by XRD, FTIR and TEM. The influence of phase structure, calcination temperature and Eu^3＋ doping concentration on luminescence properties was investigated. The results show that the materials obtained at calcination temperature below 900 ℃ mainly present non-crystal state, while the materials mainly exhibit crystal state structure when calcined over 900 ℃. The particle size increased with the calcination temperature. The particle size was 15-45 nm and 60-80 nm for amorphous and crystal forms, respectively. The excitation and emission spectra of materials are all affected by phase structure, calcination temperature and Eu^3＋ doping concentration. For Y2-xSiO5：Eux nanocrystal samples, in excitation spectra the charge transfer state （CTS） in crystal state absoption peak appeared red-shifted obviously compared with that in amorphous form, and in emission spectra the strong emission peak corresponding to ^5D0→^7F2 transition was observed and its intensity increased and decreased, respectively, with the calci nation temperature for amorphous samples and crystal samples, at the same time two novel sharp emissions peaks were found at longer wavelength and became stronger with particle size. The spectra with respect to the ^5D0→^7F1 transition splitted into sharp triple peaks, but the emission spectra corresponding to ^5D0→^7F0 transition was almost not affected by the crystal phase and the particle size. While in the crystal Y2-xSiO5：Eux of 60-80 nm, the luminescence intensities of ^5D0→^7F2 and ^5D0→^7F1 transitions were influenced by Eu^3＋ doping concentration, when the Eu^3＋ doping concentration was at x=0.4, the luminescence intensity was the strongest.