X射线衍射-红外光谱-扫描电镜表征超声辅助合成GdPO_4:Ce,Tb纳米材料形貌及光学性质

Morphology and Photoluminescence Properties of the GdPO_4: Ce,Tb Nanomaterials with Ultrasonic-assisted Synthesis Characterized by X-ray Diffraction,Infrared Spectroscopy and Scanning Electron Microscopy

超声辅助方法是制备纳米材料的有效手段,可提高纳米材料的磁学、光学等特殊性能。本文在不同p H条件下超声辅助合成GdPO_4:Ce,Tb三元体系荧光粉,采用X射线粉末衍射、傅里叶变换红外光谱、扫描电镜、透射电子显微镜及光致发光荧光光谱分析方法对样品进行了表征。结果表明:①样品仅在p H=1时,才能生成规则的15 nm×104nm六方晶系纳米棒状正磷酸盐绿色荧光粉,晶体优先选择(102)及(200)晶面生长;p H<1无法得到样品;p H>1为颗粒状的正磷酸盐绿色荧光粉。②进一步验证了Gd、Ce、Tb三元体系中Ce^(3+)离子能量较高的5d组态将能量传递给Gd^(3+)离子,而Gd^(3+)离子的跃迁发射与Tb^(3+)离子的吸收峰有较大的光谱重叠,故传递途径是Ce^(3+)→Gd^(3+)→Tb^(3+);少量Ce^(3+)的引入可提高以GdPO_4基质发光材料的发光强度。此结果可为开发稀土材料提供理论依据。

Ultrasonic assisted method is an effective method to prepare nanomaterials, which can improve their magnetic and optical properties. Described in this paper, GdPOn：Ce, Tb ternary system fluorescent powder was synthesized under different pH conditions by ultrasonic-assisted. Optical and structural properties of the fluorescent powder were determined by X-ray Powder Diffraction （XRD） , Fourier Transform Infrared Spectroscopy （ FTIR）, Scanning Electron Microscopy （SEM） , Transmission Electron Microscopy （TEM） and Photoluminesce （PL）. The following conclusions are drawn： （ 1 ） When pH = 1, synthetic samples are 15 nm × 10^4 nm hexagonalnanobars like orthophosphate, green phosphor. Cystals prefer growing at the face of （ 102 ） and （ 200 ）. When pH 〈 1, no samples can be synthesized, whereas granular orthophosphate green phosphors were synthesized when pH 〉 1. （2） A possible formation mechanism has been put forward, which provided further evidence for the fluorescent efficiency enhancement. Because the 5d energy states of Ce3＋ ions are high, they can be transferred to the Gd3＋ ions efficiently. However, the emission transition peak of Gd3 ＋ ions and the absorption peak of Tb3 ＋ ions have large spectral overlap in the Gd, Ce, Tb ternary system. Therefore, the sequence of energy transmission is the Ce3＋→ Gd3 ＋→Tb3 ＋ A few Ce3＋ ions doping to GdPO4 matrix can enhance fluorescence intensity of the luminescent materials. The result provides theoretical basis for the exploit of rare earth materials.