Chain dependent crystal chemistry and temperature-dependent properties of mullite-type related materials with stereo-chemically active lone electron pairs

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The project offers the possibility to comparably investigate synthetic single octahedral-chain inorganic material of their respective rarely investigated mineral analogues with chains in two different configurations. This includes the refinement of their crystal structures and the determination of the corresponding physico-chemical properties together with temperature-dependent changes of the structure-property correlation. The investigation of such compounds would be a valuable development for the cross-connecting inorganic crystal chemistry, crystallography and mineralogy. The main topics of the project are the formation and crystal chemical investigation of new compounds related to known mullite-types with lone-electron pair elements. Structures of interest are mainly α- and β-PbMBO4 or chemical extensions. As we have developed a quite powerful Debye-Einstein-Anharmonicity (DEA) microscopic model to describe the thermal expansion, the phonon energy and the corresponding phonon behavior could be compared, based on the Mie-Grüneisen approximation, with temperature-dependent infrared and Raman and UV/Vis spectroscopic measurements. On the other hand the phonon behavior will be calculated using DFT calculations, carried out in cooperation with our Argentinian partner.