Influence of pH in Obtaining Indium Tin Oxide Nanoparticles by Microwave Assisted Solvothermal Method

A systematic study about synthesis of In1-xSnxO2 (ITO) nanostructured crystals by microwave-assisted solvothermal method is reported. Different solutions using InCl3.4H2O and SnCl4.5H2O precursors in ethylene glycol solvent were prepared in distinct pHs (acid and basic ones). The syntheses were performed at 200 ºC using a heating rate of 50 ºC min-1 and soaking time of 30 minutes. All the synthesized powders were characterized by X-ray Diffraction (XRD) and Rietveld refinement to study the phase evolution as a function of pH. The materials synthesized in the pH ranging between 11.5 and 11.9 were further studied by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) techniques. As ITO materials have many practical applications due to their transparency in the visible spectrum, UV-Vis spectroscopy analysis was performed to obtain the optical band gap and the respective optical window.

本文报道了一项采用微波辅助溶剂热法合成In₁₋ₓSnₓO₂（铟锡氧化物，Indium Tin Oxide，简称ITO）纳米结构晶体的系统性研究。以乙二醇为溶剂，以InCl₃·4H₂O与SnCl₄·5H₂O为前驱体，配制了不同pH值（酸性与碱性）的反应溶液。所有合成反应均在200℃下进行，升温速率为50℃·min⁻¹，保温时长为30分钟。所有合成粉体均通过X射线衍射（X-ray Diffraction，简称XRD）与里特维尔德精修（Rietveld refinement）进行表征，以探究物相演变随pH值的变化规律。针对pH值介于11.5至11.9之间的合成材料，进一步采用场发射扫描电子显微镜（Field Emission Scanning Electron Microscopy，简称FE-SEM）与透射电子显微镜（Transmission Electron Microscopy，简称TEM）技术开展表征分析。鉴于铟锡氧化物材料在可见光波段具有优异透光性，具备诸多实际应用价值，本研究通过紫外-可见分光光度（Ultraviolet-Visible Spectroscopy，简称UV-Vis）分析获取了其光学带隙与对应的光学窗口参数。