The Elusive Structure of Magadiite, Solved by 3D Electron Diffraction and Model Building

Abstract

In addition to a great swelling ability, layered silicates also allow the functionalization of their interlayer region to form various robust green materials that are used as CO 2 adsorbents, drug carriers, or catalysts. Here, the unique magadiite structure, which has resisted elucidation despite many attempts and applications the material offers, is finally described. A materialspecific strategy allowed the use of 3D electron diffraction which led to the success of deciphering the atomic structure. In order to enable an ab initio structure solution of the electron beam sensitive material, a sodium-free dehydrated form of magadiite was synthetically isolated, and, from that, it was subsequently possible to derive a structure model for the sodium form of magadiite, later successfully refined against powder X-ray diffraction data. Furthermore, a geometry optimization and simulations of spectroscopic data with DFT methods confirm the obtained crystal structure of sodium magadiite. These results finally prompted a detailed description of the layers and of the chemically active interlayer region and provide a huge impact toward the design of new and more efficient materials based on functionalized magadiite and related structures.

NMR Studies of the Dehydroxylation and Rehydroxylation (RHX) of Clays with Respect to the RHX Dating of Ceramic Materials

“…Whereas 1 H NMR results would suggest that this is the interlayer water signal, which disappears above temperatures higher than 400 °C, 2 H NMR shows the presence of these species even at higher temperatures, pointing out to SiOD groups with high mobility. The structure of magadiite was recently discussed by Krysiak et al They used 3D electron diffraction and model building to solve the magadiite structure of Na- and NH 4 -magadiite. In their structure models, there are only OH groups located on the interface between the tetrahedral silicate layer and the interlayer.…”

Design of Active Defects in Semiconductors: 3D Electron Diffraction Revealed Novel Organometallic Lead Bromide Phases Containing Ferrocene as Redox Switches

“…[41,51] Nevertheless, especially in hybrid layered systems, besides beam sensitivity, stacking disorder is another difficulty that often requires a combination of several methods such as 3D ED, PXRD, modeling/simulation, and DFT calculations. [41,52] The solid phases of [FcC 2 Br] Pb and [FcC 4 Br] Pb have been investigated with 3D ED, resulting in the composition (FcC 2 ) PbBr 3 and (FcC 4 ) 4 Pb 3 Br 10 , respectively. The crystallographic details of all three phases are summarized in Figure 2 and Table 1 and will be discussed here in detail.…”

“…It could be shown that the development of fast acquisition protocols [45,50] allows the use of this technique with various transmission electron microscopes (TEMs) even for very beam sensitive materials. [41,51] Nevertheless, especially in hybrid layered systems, besides beam sensitivity, stacking disorder is another difficulty that often requires a combination of several methods such as 3D ED, PXRD, modeling/simulation, and DFT calculations. [41,52] The solid phases of [FcC 2 Br] Pb and [FcC 4 Br] Pb have been investigated with 3D ED, resulting in the composition (FcC 2 ) PbBr 3 and (FcC 4 ) 4 Pb 3 Br 10 , respectively.…”

“…The underlying idea is that doping of the perovskite material occurs when the number of oxidized ferrocenium (Fc + ) species is low and suddenly cooperative effects, when the density of Fc + increases. For the comprehensive characterization of the structural properties, a combination of 3D electron diffraction (ED), [40,41] modeling, powder X-ray diffraction (PXRD) supported by density functional theory (DFT) calculations, was used to enable the structure determination of the fine-crystalline powder materials. Subsequently, electronic, optical, and redox properties were characterized using X-ray photoelectron spectroscopy (XPS) and PES on air (PESA), UV-vis, and photoluminescence.…”

3D electron diffraction study of terrestrial iron oxide alteration in the Mineo pallasite

“…In Earth sciences, 3D ED has been used for the structure elucidation of nanoscopic inclusions (Xiong et al , 2020), mineral seeds (Németh et al , 2018), hydrated phases (Mugnaioli et al , 2020a; Krysiak et al , 2021) and modulated systems (Lanza et al , 2019; Steciuk et al , 2020), even when characterised by very large asymmetric units (Rozhdestvenskaya et al , 2010; Mugnaioli et al , 2020b). 3D ED has been applied to geological samples in different contexts (Mugnaioli and Gemmi, 2018), and in particular for the characterisation of meteorites (Pignatelli et al , 2017, 2018; Suttle et al , 2021), impactites (Campanale et al , 2021), cryptocrystalline oxides (Koch-Müller et al , 2014) and hydroxides (Viti et al , 2016).…”