MS26-P02 Polymorphism of NiSeO3(H2O) studied on multiphase crystals Morgane POUPON (Department of Structure Analysis Fyzikální Ústav AV ČR, v. v. i, Prague, Czech Republic) Nicolas Barrier (CRISMAT Laboratory, CAEN, France) Olivier Perez (CRISMAT Laboratory, CAEN, France) Michal Dušek (Department of Structure Analysis Fyzikální Ústav AV ČR, v. v. i, Prague, Czech Republic) Václav Petříček (Department of Structure Analysis Fyzikální Ústav AV ČR, v. v. i, Prague, Czech Republic)email: poupon@fzu.czInorganic materials with a layered structure are interesting for their potential exchange and/or storage properties [1]. These structures typically have weak intermolecular bonds between their different layers, like Van der Waals or hydrogen bonds [2].  However, weak bonds may lead to stacking faults or the intergrowth of phases inside the crystal. These defects could induce diffuse scattering and additional reflections, which can be observed on the reciprocal planes reconstructed from X-ray single crystal measurement. Understanding this complex order can allow us to solve structures of metastable polymorphs and to apprehend the processes of transformation towards their stable states. The family of lamellar compounds MSeO3(H2O) (M = Mn, Co, Ni, Zn, Cd) [3] is of interest regarding their several polymorphs. The cohesion of these structures is provided by hydrogen bonds. The NiSeO3(H2O) crystals were synthesized using hydrothermal synthesis under low-pressure and low-temperature conditions.
We will present how the formalism of (3 + 1)d superspace can help to reveal the crucial role of weak interaction and the existence of intergrowth between two polymorphs in the crystal. Then, we will present the temperature stability study using low and high-temperature single crystal X-ray diffraction measurements of these multiphase crystals.
References:

[1] Mishra, G. et al. Appl. Clay Sci. 2018, 153, 172–186.
[2] Shamim, M. et al. J. Mol. Struct. 2016, 1125, 27–35.
[3] Engelen, B. et al. Für Anorg. Allg. Chem. 1996, 622 (11), 1886–1892.
Keywords: Hydrogen, Layers, Superspace