SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 42: Interface Controlled Properties and Nanomaterials: Nanoporous Materials and Nanolaminates

MM 42.8: Vortrag

Donnerstag, 30. März 2023, 17:45–18:00, SCH A 215

An Improved Kernel-Based NMR Cryoporometry Characterization of Mesoporous Solids — •Henry R. N. B. Enninful and Rustem Valiullin — Faculty of Physics and Earth Sciences, Felix Bloch Institute for Solid State Physics, Leipzig University, Linnéstraße 5, 04103, Leipzig, Germany.

NMR cryoporometry is a pore space characterization technique for industrial and natural materials such as catalysts, gas storage materials, cartilage, bones, rocks and many more. While gaining wide use, the fundamental phenomena underlying solid-liquid phase transitions in geometrically disordered porous materials is still not fully understood. This may lead to inaccurate pore size distributions from the NMR cryoporometry technique.

In this work, we have developed a new approach to NMR cryoporometry. Herein, it takes account of cooperativity effects in pores, the existence of a variable non-frozen layer (NFL) thickness between the frozen core and pore wall and the effect of curvature on thermal fluctuations in pores which hitherto are missing in the current approach. In the first place, we compile a family of transition curves characterizing the phase state in pores with different pore sizes, so called kernels. Thereafter, we apply a general framework for predicting phase equilibria in collection of pores. We demonstrate the new approach by first applying it to ordered porous materials such as MCM-41 and SBA-15. Further more, the technique is used to characterize a highly disordered random porous material where we reproduce all states seen in the material. A more accurate pore size distribution (PSD) is, thus, obtained.