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纳米氧化铋是一种重要的功能材料,其可控制备一直是研究的热点。以Triton X-100/正庚烷/正戊醇/水为微乳液体系,采用反相微乳法合成了一维四棱柱状Bi2O3纳米棒。采用X射线衍射(XRD)和扫描电镜(SEM)表征了煅烧温度和煅烧时间对Bi2O3样品晶型和微观形貌的影响。表征结果表明,随煅烧温度增加,产物由四方相b-Bi2O3向单斜相a-Bi2O3转变,样品为一维四棱柱状纳米棒,其直径为50~100 nm,长为300~600 nm。对前驱体的形成机理进行分析发现,定向附着、自组织和奥斯瓦尔德熟化在微乳体系合成纳米材料的过程中起到了重要作用。紫外-可见光谱(UV-Vis)分析表明,亚稳相b-Bi2O3(550 nm)相比稳定相a-Bi2O3(460 nm)具有更宽的可见光响应范围和更窄的禁带宽度(分别为2.30 eV和2.74 e V),属于电子从价带跃迁到导带引起的吸收,为Bi2O3的直接带隙吸收。荧光光谱(PL)表明b-Bi2O3在400~600 nm具有宽的发射谱带,466 nm处的强蓝带发射归属于Bi3+的3P1→1S0跃迁和O2-→Bi3+荷移跃迁,562 nm处绿峰归属于晶体表面氧空位和生长过程中形成的缺陷。
Nanometer bismuth oxide is an important functional material, and its controllable preparation has been a hot spot of research. One-dimensional, four-prismatic Bi2O3 nanorods were synthesized by reversed-phase microemulsion using Triton X-100 / n-heptane / n-amyl alcohol / water as the microemulsion system. The effects of calcination temperature and calcination time on the crystal structure and microstructure of Bi2O3 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Characterization results show that with the increase of calcination temperature, the product is transformed from tetragonal phase b-Bi2O3 to monoclinic a-Bi2O3. The sample is a one-dimensional quadrangular prism-shaped nanorods with a diameter of 50-100 nm and a length of 300-600 nm. The formation mechanism of the precursors was analyzed and it was found that orientation, self-organization and Oswald ripening played an important role in the synthesis of nanomaterials in microemulsion system. UV-Vis analysis shows that the metastable bismuth b-Bi2O3 (550 nm) has a wider visible-light response and a narrower bandgap than the stable phase a-Bi2O3 (460 nm) 2.30 eV and 2.74 eV) belong to the absorption caused by the electron transition from the valence band to the conduction band, which is the direct band gap absorption of Bi2O3. Fluorescence spectrum (PL) shows that b-Bi2O3 has a wide emission band at 400-600 nm, strong blue band emission at 466 nm belongs to the 3P1 → 1S0 transition and the O2- → Bi3 + transition of Bi3 +, and the emission at 562 nm Peak attributable to the crystal surface oxygen vacancies and defects in the growth process.