Effect of hydrolysis catalyst on the Ti deficiency and crystallite size of sol-gel-TiO_2 crystalline phases
Effect of hydrolysis catalyst on the Ti deficiency and crystallite size of sol-gel-TiO_2 crystalline phases
复制标题
DOI：
10.1557/jmr.1995.2788
复制
发表时间：
1995-11
影响因子：
2.7
通讯作者：
Bokhimi A. Morales;O. Novaro;T. López;E. Sánchez;R. Gómez
中科院分区：
文献类型：
--
作者：
Bokhimi A. Morales;O. Novaro;T. López;E. Sánchez;R. Gómez
采用不同的水解催化剂制备了溶胶-凝胶二氧化钛，并用X-射线粉末衍射法对其进行了表征。利用Rietveld技术对在70℃到900℃之间热处理的样品的晶相--板钛矿相、锐钛矿相和金红石相--的结构进行了细化。通过细化得到了各相的结构参数、各相的浓度和平均微晶尺寸。这些量及其随温度的变化取决于水解催化剂。锐钛矿型和金红石型缺钛，说明它们的晶体结构中含有氢原子，内部形成了OH、−离子。在锐钛矿型中，这一缺陷取决于其微晶尺寸，但在金红石型中是恒定的。当锐钛矿被退火时，它会脱羟基化，要么生成结晶，要么转化为金红石。通过分析，我们还找到了获得单相样品的条件，这些样品可以作为制备二氧化钛单相薄膜的前驱体。
We prepared sol-gel titania by using different hydrolysis catalysts, and characterized it by x-ray powder diffraction. The structure of the crystalline phases—brookite, anatase, and rutile—in the samples annealed between 70 and 900 °C was refined by using the Rietveld technique. From the refinement we obtained the structure parameters, the concentration of each phase, and their average crystallite size. These quantities and their evolution with temperature depended on the hydrolysis catalyst. Anatase and rutile were deficient in Ti, suggesting that their crystalline structure contained hydrogen atoms, forming OH^− ions inside. In anatase this deficiency depended on its crystallite size, but it was constant in rutile. When anatase was annealed, it dehydroxylized, producing either crystallitc growing up or its conversion into rutile. From the analysis we also found the conditions for obtaining single-phase samples that could be used as precursors for making up titania single-phase thin films.