Hybrid glasses from strong and fragile metal-organic framework liquids.
Hybrid glasses from strong and fragile metal-organic framework liquids.
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DOI：
10.1038/ncomms9079
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发表时间：
2015-08-28
影响因子：
16.6
通讯作者：
Greaves GN
中科院分区：
文献类型：
--
作者：
Bennett TD;Tan JC;Yue Y;Baxter E;Ducati C;Terrill NJ;Yeung HH;Zhou Z;Chen W;Henke S;Cheetham AK;Greaves GN
混合玻璃将新兴的金属有机框架（MOFs）领域与这些化学通用系统的玻璃形成、非晶化和熔融过程联系起来。虽然无机沸石在玻璃化转变附近坍塌并在较高温度下熔融，但迄今为止尚未研究非晶化与熔融之间的关系。在这里，我们展示了如何加热沸石拓扑结构的MOFs首先导致低密度的“完美”玻璃，类似于在冰，硅和二糖中形成的那些。这种有序-有序的转变导致了一种低脆性的超强液体，在随后的有序-无序转变之前，这种液体动态地控制着崩溃，从而产生了一种更脆弱的高密度液体。在结晶成致密相（其可以再熔化）之后，随后的淬火产生与高密度相几乎相同的块状玻璃。我们提供的证据表明，宽范围的熔融温度的沸石分子筛的MOFs与它们的网络拓扑结构，并开辟了“熔铸”的MOF玻璃的可能性。 迄今为止，合成杂化材料中结晶度和非晶度之间的精细界面相对未被探索。在这里，作者探讨了沸石金属有机框架的非晶化和熔融行为之间的关系，作为功能玻璃的一种途径。
Hybrid glasses connect the emerging field of metal-organic frameworks (MOFs) with the glass formation, amorphization and melting processes of these chemically versatile systems. Though inorganic zeolites collapse around the glass transition and melt at higher temperatures, the relationship between amorphization and melting has so far not been investigated. Here we show how heating MOFs of zeolitic topology first results in a low density ‘perfect' glass, similar to those formed in ice, silicon and disaccharides. This order–order transition leads to a super-strong liquid of low fragility that dynamically controls collapse, before a subsequent order–disorder transition, which creates a more fragile high-density liquid. After crystallization to a dense phase, which can be remelted, subsequent quenching results in a bulk glass, virtually identical to the high-density phase. We provide evidence that the wide-ranging melting temperatures of zeolitic MOFs are related to their network topologies and opens up the possibility of ‘melt-casting' MOF glasses. The fine interface between crystallinity and amorphicity in synthetic hybrid materials has to-date been relatively under-explored. Here, the authors probe the relationship between amorphisation and melting behaviour in zeolitic metal-organic frameworks as a route towards functional glasses.