Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 46: Nanostructured Materials III

MM 46.3: Talk

Thursday, March 25, 2010, 10:45–11:00, H16

Adsorption and freezing of argon in mesoporous Vycor glass — •Klaus Schappert and Rolf Pelster — Universität des Saarlandes, FR 7.2 Experimentalphysik, Campus E 2.6, 66123 Saarbrücken, Germany

We explore the behaviour of argon in mesoporous Vycor glass focusing on the process of freezing and the elastic properties of the adsorbate itself. For this purpose we perform ultrasonic measurements of the effective shear modulus and of the longitudinal modulus. Isothermal filling cycles at temperatures above 66 K reveal that the first few wall-layers remain liquid-like, so that freezing starts only above a threshold [1]. From these measurements we infer the elastic properties of adsorbed wall layers with the aid of an effective medium analysis. In order to understand the behaviour of the wall layers we also conduct thermal cycles of partially filled pores down to about 15 K. At higher filling fractions, the macroscopic properties of the porous sample change abruptly, an effect that we discuss in terms of capillary sublimation.

[1] K. Schappert and R. Pelster, Phys. Rev. B 78, 174108 (2008)