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首页> 外文会议>International Conference on Surface and Colloid Science; 200309; Brazil >Single-source precursor and homometal approaches to the sol-gel synthesis of iron and titanium oxides
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Single-source precursor and homometal approaches to the sol-gel synthesis of iron and titanium oxides

机译：溶胶-凝胶法合成铁和钛氧化物的单源前体和均金属方法

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摘要

The recently described titanium and iron heterometal isopropoxide, [FeCl{Ti_2(OPr~i)_9}] (complex 1), has been used as a single-source sol-gel precursor to produce mixed TiO_2/Fe_2TiO_5 materials. The products were dried and submitted to thermal treatment from 55 to 1,000℃. Oxide composition and phase transitions were studied by X-ray powder diffractometry and Raman, electron paramagnetic resonance and Moessbauer spectros-copies. A mixture of nanometric-size TiO_2 (anatase, 4.3-6.1 nm) and amorphous iron(Ⅲ) oxide was obtained up to 500℃, while TiO_2 (rutile), α-Fe_2O_3 (hematite) and Fe_2TiO_5 (pseudobrookite) were found at 700℃. At 1,000℃, only rutile and pseudobrookite were observed. These results are very similar to those obtained by a homometallic approach from a 1:2 mixture of FeCl_2 and [Ti(OPr~i)_4]. Scanning electron microscopy/energy-dispersive X-ray spectros-copy results for the powder obtained from complex 1 at 1,000℃ showed no phase segregation at a submicro-metre level. The average chemical composition of different grains confirms the complete conversion of 1 to the metal oxides. The solids obtained from the homometal precursors present significant phase segregation. This indicates that complex 1 can generate oxide-oxide (nano)composites with a degree of homogeneity that cannot be achieved by an analogous multi-component route.
机译：最近描述的钛和铁杂金属异丙氧化物[FeCl {Ti_2（OPr〜i）_9}]（配合物1）已用作单一来源的溶胶-凝胶前驱体，以生产TiO_2 / Fe_2TiO_5混合材料。将产物干燥并在55至1,000℃下进行热处理。通过X射线粉末衍射和拉曼光谱，电子顺磁共振和Moessbauer光谱副本研究了氧化物的组成和相变。最高温度为500℃时，得到了纳米尺寸的TiO_2（锐钛矿型，4.3-6.1nm）和无定形氧化铁（Ⅲ）的混合物，而在700℃时发现了TiO_2（金红石），α-Fe_2O_3（赤铁矿）和Fe_2TiO_5（假板钛矿）。 ℃。在1000℃下，仅观察到金红石和假板钛矿。这些结果与通过同金属方法从FeCl_2和[Ti（OPr〜i）_4]的1：2混合物获得的结果非常相似。从络合物1得到的粉末在1000℃的扫描电子显微镜/能量色散X射线光谱分析结果表明，在亚微米水平上没有相偏析。不同晶粒的平均化学组成确定了1到金属氧化物的完全转化。从均金属前体获得的固体具有明显的相偏析。这表明配合物1可以产生具有均质度的氧化物-氧化物（纳米）复合物，这是通过类似的多组分途径无法实现的。

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