Characterisation of intergrowth in metal oxide materials using structure-mining: the case of γ-MnO₂

Abstract

Manganese dioxide MnO2 compounds are widely used in electrochemical applications e.g. as electrode materials or photocatalysts. One of the most used polymorphs is γ-MnO2 which is a disordered intergrowth of...

Local structure analysis and structure mining for design of photocatalytic metal oxychloride intergrowths

“…In this work, we combine these two approaches in a structure mining approach, developed in a previous paper. 27 A whole catalogue of supercells of intergrown Bi 4 TaO 8 Cl and Bi 2 GdO 4 Cl domains with varying amounts of Ta and Gd, as well as of disorder, are refined onto experimental datasets. The comparison of the goodness of fit between each supercell provides information on the microstructure of the sample, giving guidance for the future design of new intergrowth photocatalysts.…”

“…We recently used a similar approach for characterization of stacking disorder in γ-MnO 2 . 27 γ-MnO 2 is an intergrowth of two parent structures, pyrolusite β-MnO 2 and ramsdellite R-MnO 2 . γ-MnO 2 structures can thus be considered built through stacking of two types of building blocks: 47 [MnO 6 ] octahedra belonging to a pyrolusite domain and [MnO 6 ] octahedra of γ-MnO 2 belonging to a ramsdellite domain.…”

“…The methodology for creating supercells for structure mining has been described in detail in previous work. 27 Briefly, as further discussed below, asymmetric units of the Ta- and the Gd-domains were extracted and stacked sequentially following a set of probabilities P g and P t . 50 units were stacked in total.…”

Imperfect Battery Materials: A Closer Look at the Role of Defects in Electrochemical Performance

“…Besides, PDF analysis was also evaluated to model and quantify the crystal intergrowth of MnO 2 samples, but it was found to be less suitable than XRD pattern analysis. 149,150 ■ DISCUSSION AND PERSPECTIVES Defects Are Ubiquitous in Battery Materials and Their Impacts Remain in Many Cases Poorly Understood. All the examples presented in the previous section illustrate the profound impact of defects on the performance of battery materials.…”

“…Such structural intergrowth implies the loss of long-range ordering along one direction and prevents conventional Rietveld refinement. Besides, PDF analysis was also evaluated to model and quantify the crystal intergrowth of MnO 2 samples, but it was found to be less suitable than XRD pattern analysis. , …”