相转变制备超长α-Bi_2O_3微米棒及其表征

Synthesis and Characterization of Ultralong α-Bi_2O_3 Microrods by Phase-Transformation Method

首先利用液相沉淀法合成了BiOBr纳米片（~50nm）,然后以BiOBr纳米片为前驱体,进行焙烧,使BiOBr发生相转变,制备长度为~200μm的α-Bi2O3微米棒。运用热重（TG）、X射线粉末衍射仪（XRD）、扫描电镜（SEM）和紫外-可见漫反射光谱分析（UV-VisDRS）研究了BiOBr煅烧过程中发生的相变及形貌的变化。发现BiOBr纳米片是一种热力学不稳定的半导体,化合物中的Br元素在煅烧过程中逐步被释放。随着Br元素的释放,BiOBr在600℃转变成片状结构的Bi24O31Br10。生成的片状结构Bi24O31Br10在800℃左右完全转变成超长α-Bi2O3微米棒。这个研究结果提供了一种简单、有效合成α-Bi2O3微米棒的方法。

-50 nm BiOBr nanoplates were first fabricated by aqueous precipitation method. Then uhralong α-Bi203 microrods （-200 μm） were successfully synthesized by applying phase-transformation route with produced BiOBr nanoplates as precursor under calcination condition. The phase-transfbrmation from BiOBr to α-Bi2O3 via Bi24O31 Br10 intermediate were studied by differential thermogravimetric analysis （TGA） , X-ray powder diffraction （ XRD ） , scanning electron microscope （ SEM ） , and UV-Vis diffuse reflectance spectra （UV-Vis DRS）. It reveals that BiOBr nanoplates are not thermostable. Br element in BiOBr compound was gradually released during calacnation process. With the loss of Br, BiOBr began to transform to plate-like Bi24 O31 Br10 at around 600℃ and the produced Bi24 O31 Br10 totally converted to uhralong α-Bi203 microrods at 800 ℃. It could provide a simple and effective method to fabricate ultralong α-Bi2 03 microrods.