一维纳米材料SmPO4·0.5H2O的制备及光学性质

以氧化钐和H₃PO₄为原材料，在无模板剂的情况下，用水热法通过调控pH、时间和温度制备了SmPO₄·0.5H₂O一维纳米材料，并提出其可能形成机理。用X射线粉末衍射（XRD）、透射电镜（TEM，HRTEM和SAED）、红外光谱（IR）和能谱（EDS）对产物的物相结构、微观形貌和组成进行了表征。用紫外-可见吸收光谱研究了产物的光学性质。研究结果表明，实验所制备的产物全部是六方晶系结构，形貌都为一维纳米线。反应体系的pH值、温度和时间的改变对纳米线的长径比有影响，但对其相结构基本都没有影响。分析得到最佳水热制备条件为pH=5、温度和时间分别为130℃和8 h，产物的结晶性、分散性和均匀性都达到最好。光学性质研究表明，该类产物在300~350 nm的紫外区域有吸收宽峰，是属于基质O^2-→P⁵⁺、Sm³⁺的电荷迁移。在350~450 nm处的可见光区域内也有一组吸收峰，是属于Sm³⁺的4f内层电子间的f-f跃迁吸收。依据该类吸收峰，得到禁带宽度在4.67~5.50 eV之间。pH值和温度对产物光学性能均有影响。

Preparation and Optical Properties of One-dimension Nanomaterial SmPO4·0.5H2O

One-dimensional nanomaterial SmPO₄·0.5H₂O was synthesized using hydrothermal method from samarium oxide and H₃PO₄ in the absence of a template agent. Effects of pH, reaction time and temperature, and the possible formation mechanism were invetisgated. The phase structure, microstructure and composition of the products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy(TEM, HRTEM and SAED), infrared spectroscopy (IR) and energy dispersive spectroscopy(EDS). The optical properties of the products were studied by absorption spectra. It is shown that all the products prepared by the experiment adopthexagonal crystal structure, and the morphology is a one-dimensional nanowire. Theratio of length to diameter in nanowires was significantly influenced by pH value, temperature and time of the reaction system, which have no effect on the phase structure. The optimum conditions of hydrothermal preparation are pH=5, 130℃ and 8 h, respectively. The crystallization, dispersion and uniformity of the products are best on this condition. The studies of optical properties show that there products have an absorption wide peak in the ultraviolet region of 300-350 nm. The wide peak belongs to the charge transfer band (CTB) of O^2-→P⁵⁺,Sm³⁺. A set of absorption peaksare observed in the visible region of 350-450 nm, which belong to the f-f transition absorption between the 4f inner-layer electrons of Sm³⁺.According to these absorption peaks, the band gap energy(E_g) is 4.67-5.50 eV. The pH value and temperature have effects on optical properties of the products.