Investigating the structure of mesoporous amorphous magnesium carbonate
Abstract
Investigating the structure of mesoporous amorphous magnesium carbonate
Upsalite® is a recently discovered mesoporous magnesium carbonate material with a pore size of ~ 7 nm. Upsalite® is synthesized without the aid of surfactants. Until now, the chemical structure, and the factors governing the textural properties of Upsalite® are not fully known. For instance, the smallest repeatable unit is not determined. It is also not yet established whether Upsalite® can be classified as a polymer. In this project we would like to determine the detailed structure of Upsalite® using state of the art techniques. These techniques include X-ray Synchrotron measurements, various spectroscopic techniques (infrared, nuclear magnetic resonance, NMR, etc) and quantum mechanical calculations.
The structure of amorphous materials can usually not easily be found. Reasons to this are that measurements on materials without long range order are few and often complex. Standard methods such as X-ray diffraction cannot be used. To capture the structural properties of these materials, methods based on synchrotron radiation are often needed.
Computational models of amorphous materials are difficult since these are often limited to size in space. In practice, the best model of a material without long range order would be infinite, demanding infinite computer resources. There are however methods viable also with limited computational effort, still resulting in reasonable structural as well as energetic descriptions of an amorphous materials. In this project we would like to apply one of those, stochastic quenching (SQ) . The SQ method has previously shown to accurately describe the potential energy landscape of metallic liquids as well as oxides and carbon like materials , , , , , Structures will be generated and the local energy minimum of each structure will be calculated by use of Density Functional Theory.
We also have the possibility to gather more information related to the structure of Upsalite® , using NEXAFS and RIXS. We would therefore like to extract the electronic properties of the generated structures and calculate reasonable spectroscopic properties. This requires excited states theory methods that are especially computationally demanding.
Our hopes with this project is to uncover the structural details of this fascinating material, which until recently was believed to be impossible to synthesise.
