Unusually Large Band Gap Changes in Breathing Metal鈥揙rganic Framework Materials

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• 作者：Sanliang Ling ; Ben Slater
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：July 23, 2015
• 年：2015
• 卷：119
• 期：29
• 页码：16667-16677
• 全文大小：466K
• ISSN：1932-7455

文摘

Many of the potential applications for metal鈥搊rganic frameworks (MOFs) focus on exploiting their porosity for molecular storage, release, and separation, where the functional behavior is controlled by a subtle balance of host鈥揼uest interactions. Typically, the host structure is relatively unperturbed by the presence of guests; however, a subset of MOFs exhibit dramatic phase-change behavior triggered by the adsorption of guests or other stimuli, for which the MIL-53 material is an archetype. In this work, we use density functional approaches to examine the electronic structure changes associated with changes of phase and density and find the associated change in band gaps can be larger than 1 eV for known MIL-53-type materials and hypothecated structures. Moreover, we show that internal pressure (via guest molecules) and external pressure can exert a major influence on the band gap size and gap states. The large response in electronic properties to breathing transitions in MOFs could be exploitable in future applications in resistive switching, phase-change memory, piezoresistor, gas-sensing and thermochromic materials.