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O: Fachverband Oberflächenphysik

O 57: Poster Session - Surface Dynamics: Phase Transitions and Elementary Processes

O 57.1: Poster

Dienstag, 17. März 2020, 18:15–20:00, P2/2OG

Phase transitions in geometrically disordered porous solids: from strong to weak disorder — •Henry R. N. B. Enninful, Dirk Enke, and Rustem Valiullin — Universität Leipzig, Leipzig, Germany

Mesoporous solids are widely used in various applications in catalysis, separations, adsorption, drug delivery, gas and energy storage, among others. Establishing their pore structure is therefore of direct practical relevance. While the state-of-the-art characterization approaches perform extremely well for ordered mesoporous solids, the occurrences of the cooperativity effects in phase transitions coupled with very complex morphological structures of the pore networks make these approaches not directly applicable for disordered materials. In this respect, better understanding of phase equilibria is needed.

In this contribution, we discuss the potentials of a recently developed serially connected pore model (SCPM) which intrinsically contains both the cooperativity effects and structural complexity. Notably, the governing equation derived within SCPM may be considered as an extension of the general adsorption isotherm (GAI) equation to include the network effects. We show the freezing and melting transitions (analogues of capillary evaporation and capillary condensation, respectively) complemented by the freezing scanning behavior (analogue of capillary evaporation scans) for a family of porous glasses with different pore sizes.

References [1] Scientific Reports, 7, 7216, 2017. [2] JPCC C, 123, 16239, 2019 [3] Frontiers in Chemistry, doi: 10.3389/fchem.2019.00230.