Phase diagrams of liquid-phase mixing in multi-component metal-organic framework glasses constructed by quantitative elemental nano-tomography
Phase diagrams of liquid-phase mixing in multi-component metal-organic framework glasses constructed by quantitative elemental nano-tomography
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DOI：
10.1063/1.5120093
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发表时间：
2019-09-01
期刊：
影响因子：
6.1
通讯作者：
Midgley, Paul A.
中科院分区：
文献类型：
--
作者：
Collins, Sean M.;MacArthur, Katherine E.;Midgley, Paul A.
最近报道了几种不同的混合工艺和由此产生的微观结构在由多种金属有机框架制备的多组分玻璃中。本文研究了两种多组分沸石基吡唑盐框架（ZIF）玻璃，即（a(T)ZIF-4- co）（0.5）（a(g)ZIF-62）（0.5）共混物和a(g)[(ZIF-67)(0.2)(ZIF-62)(0.8)]助熔剂熔融玻璃。用扫描透射电子显微镜对这些材料进行了定量x射线能谱表征。通过使用任意形貌标准推进部分电离截面方法，实现了整个玻璃体积的定量纳米级元素分析。反过来，描述混合状态的相图被提出，为观察到的微观结构的形成提供了机制的见解。在a(g)[(ZIF-67)(0.2)(ZIF-62)(0.8)]中观察到显著的混相性。这些发现表明，相偏析和相互扩散是多组分玻璃形成的两个过程，这解释了在混合和熔剂熔化过程中观察到的不同结果。
Several distinct mixing processes and resulting microstructures have recently been reported in multicomponent glasses prepared from multiple metal-organic frameworks. Here, two illustrative examples of multicomponent zeolitic imidazolate framework (ZIF) glasses, the (a(T)ZIF-4-Co)(0.5)(a(g)ZIF-62)(0.5) blend and the a(g)[(ZIF-67)(0.2)(ZIF-62)(0.8)] flux melted glass, are studied. These materials are characterized by quantitative X-ray energy dispersive spectroscopy in the scanning transmission electron microscope. By advancing a partial ionization cross section methodology using standards of arbitrary morphology, quantitative nanoscale elemental analysis throughout the glass volume is achieved. In turn, phase diagrams describing the mixing states are presented, offering mechanistic insight into the formation of the observed microstructures. Significant miscibility was observed in a(g)[(ZIF-67)(0.2)(ZIF-62)(0.8)]. These findings establish phase-segregation and interdiffusion as two processes in multicomponent glass formation, which explains the different outcomes observed in blending and flux melting.