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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Determining the Location and Role of Al in Al-Modified TiO2 Nanoparticles Using Low-Temperature Heat Capacity, Electron Energy-Loss Spectroscopy, and X-ray Diffraction
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Determining the Location and Role of Al in Al-Modified TiO2 Nanoparticles Using Low-Temperature Heat Capacity, Electron Energy-Loss Spectroscopy, and X-ray Diffraction

机译：使用低温热容，电子能谱和X射线衍射确定Al在Al修饰的TiO2纳米颗粒中的位置和作用

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摘要

The location and function of clopants in metal oxide nanopartides have been poorly characterized for many systems. We have performed heat capacity measurements, electron energy-loss spectroscopy (EELS), and X-ray diffrattion (XRD) on 10 TiO2 fianoparticle samples that have different amounts of Al dopant to determine the location and function of the Al3+ cations. From the heat capacity data, lattice vacancies are observed to increase significantly with the addition of the Al dopant, suggesting Al' cations enter the TiO2 lattice and create vacancies due to the charge difference between Al3+ and Ti4O. The presence of gapped terms in fits of the lowtemperature heat capacity data also suggests that small regions of short-range order are created within the TiO2 lattice. Entropies at T = 298.15 K were determined from the heat capacity data and show effects related to the entropy of mixing, suggesting that a solid solution of Al/TiO2 is formed. EELS data confirm that Al enters the TiO2 lattice but also indicates that the short-range structure around the Al atoms shifts from a Ti02like environment toward an Al2O3-like environment as the dopant concentration increases. XRD data suggest that the long-range order of the particles decreases as the dopant concentration increases but retains a basic TiO2-like structure. This is the first investigation to use heat capacity data in this manner to determine the location of the dopant.
机译：在许多系统中，金属氧化物纳米粒子中凝结剂的位置和功能很难得到表征。我们对10种含有不同Al掺杂量的TiO2细颗粒样品进行了热容量测量，电子能量损失谱（EELS）和X射线衍射（XRD），以确定Al3 +阳离子的位置和功能。根据热容量数据，观察到晶格空位随着添加Al掺杂剂而显着增加，这表明Al'阳离子进入TiO2晶格并由于Al3 +和Ti4O之间的电荷差异而产生了空位。符合低温热容数据的间隙项的存在还表明，在TiO2晶格内产生了短程有序的小区域。从热容数据确定T = 298.15 K时的熵，并显示出与混合熵有关的效应，表明形成了Al / TiO2固溶体。 EELS数据证实了Al进入TiO2晶格，但也表明随着掺杂剂浓度的增加，Al原子周围的短程结构从类Ti02环境转变为类Al2O3环境。 XRD数据表明，随着掺杂剂浓度的增加，颗粒的长程顺序减小，但保留了基本的TiO2样结构。这是首次以这种方式使用热容量数据来确定掺杂剂位置的研究。

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