The effect of TiO(2) on nucleation and crystallization of a Li(2)O-Al(2)O(3)-SiO(2) glass investigated by XANES and STEM.
The effect of TiO(2) on nucleation and crystallization of a Li(2)O-Al(2)O(3)-SiO(2) glass investigated by XANES and STEM.
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DOI：
10.1038/s41598-018-21227-x
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发表时间：
2018-02-13
影响因子：
4.6
通讯作者：
Rüssel C
中科院分区：
文献类型：
--
作者：
Kleebusch E;Patzig C;Krause M;Hu Y;Höche T;Rüssel C
基于Li2O/Al2O3/SiO2的玻璃陶瓷具有很高的经济重要性，因为它们通常表现出非常低的热膨胀系数。这使得许多具有挑战性的应用，如灶台面板，炉窗或望远镜镜面坯。通常，必须通过仔细选择结晶程序和要使用的成核剂的类型来定制玻璃内所需LAS晶体相的结晶。本研究描述了在仅含有TiO2作为成核剂的LAS碱组合物中形成纳米晶TiO2。使用扫描透射电子显微镜和x射线吸收光谱的组合，发现在玻璃中已经存在四倍和六倍配位Ti4+离子的混合物。将玻璃加热到740°C，立即改变这一比例，使其具有高含量的六倍配位Ti，其积聚在液-液相分离液滴中。在热处理过程中，这些液滴最终演变成纳米TiO2沉淀，其中Ti4+为6倍配位。因此，研究表明纳米TiO2的成核是由钛离子在非晶玻璃基体中的逐渐重排引起的，从四重配位到六重配位。
Glass ceramics based on Li2O/Al2O3/SiO2 are of high economic importance, as they often show very low coefficients of thermal expansion. This enables a number of challenging applications, such as cooktop panels, furnace windows or telescope mirror blanks. Usually, the crystallization of the desired LAS crystal phases within the glasses must be tailored by a careful choice of crystallization schedule and type of nucleation agents to be used. The present work describes the formation of nanocrystalline TiO2 within an LAS base composition that contains solely TiO2 as nucleating agent. Using a combination of scanning transmission electron microscopy as well as X-ray absorption spectroscopy, it is found that a mixture of four- and six-fold coordinated Ti4+ ions exists already within the glass. Heating of the glass to 740 °C immediately changes this ratio towards a high content of six-fold coordinated Ti, which accumulates in liquid-liquid phase-separation droplets. During the course of thermal treatment, these droplets eventually evolve into nanocrystalline TiO2 precipitations, in which Ti4+ is six-fold coordinated. Thus, it is shown that the nucleation of nanocrystalline TiO2 is initiated by a gradual re-arrangement of the Ti ions in the amorphous, glassy matrix, from a four-fold towards a six-fold coordination.
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影响因子：
5
作者：
Farges, F;Brown, GE;Rehr, JJ
通讯作者：
Rehr, JJ
影响因子：
4.7
作者：
Hu, Anmin;Li, Ming;Mao, Dali
通讯作者：
Mao, Dali
影响因子：
4.5
作者：
Kleebusch, Enrico;Patzig, Christian;Ruessel, Christian
通讯作者：
Ruessel, Christian
DOI：
10.1111/j.1151-2916.1999.tb01716.x
发表时间：
1999-01-01
影响因子：
3.9
作者：
Beall, GH;Pinckney, LR
通讯作者：
Pinckney, LR
影响因子：
5
作者：
Farges, F;Brown, GE;Rehr, JR
通讯作者：
Rehr, JR