铜源对溶胶-凝胶法制备La_2CuO_4晶体及光学性能的影响

Effects of Different Copper Sources on Preparation and Optical Property of La_2CuO_4 Crystallites Synthesized by Sol-Gel Process

以硝酸镧为镧源,柠檬酸为络合剂,水为溶剂,分别以硫酸铜,氯化铜和硝酸铜为铜源,采用溶胶-凝胶法制备了La2CuO4纳米晶。通过热重-示差扫描量热(TG-DSC),X射线衍射(XRD),红外光谱(IR),透射电子显微镜(TEM)和紫外-可见-近红外光谱(UV-Vis-NIR)等方法对La2CuO4粉体进行了测试和表征;研究了不同铜源对前驱体及La2CuO4粉体的热性能、相组成、官能团、显微结构及光学性能的影响。结果表明:以硫酸铜和氯化铜为铜源,600℃煅烧保温2 h,产物均含有杂质相,而以硝酸铜为铜源时,可获得单一的正交晶型的La2CuO4物相,晶粒尺寸80-100 nm。根据UV-Vis-NIR分析,La2CuO4的光学带隙依次为1.193 eV,1.258 eV,1.380 eV。

La2CuO4 crystallites were prepared via a sol-gel process using lanthanum nitrate as lanthanum source, citric acid as complexing agent, distilled water as solvent agent, and copper sulfate, copper chloride and copper nitrate as copper source respectively. The influences of different copper sources on thermal property, phase composition, functional group, microstructure and optical property of the as-prepared La2CuO4 crystallites were investigated by thermogravimetric-differential scanning calorimetry, X-ray diffraction, infrared spectrum, transmission electron microscope and UV-Vis-NIR spectrophotometer. The results show that impurity phases will be introduced when copper sulfate or copper chloride is used as copper source. Pure La2Cu04 crystallites can be obtained after calcining at 600℃ for 2 h when the copper source is copper nitrate, and the crystallites exhibit an orthogonal structure with grain size of 80-100 nm. By UV-Vis-NIR spectral analysis, the corresponding optical band gap of La2CuO4 crystallites is about 1.193 eV, 1.258 eV and 1.380 eV, when the copper source is copper sulfate, copper chloride and copper nitrate, respectively.