Evidence for a disorder induced phase transition in the condensation of 4He in aerogels

Thierry Lambert (1) , Florence Despetis (2) , Laurent Puech (1) , Pierre-Etienne Wolf (1)

1 CRTBT - Centre de Recherches sur les Très Basses Températures
2 LCVN - Laboratoire des colloïdes, verres et nanomatériaux

We report on thermodynamic and optical measurements of the condensation process of $^4$He in two silica aerogels of same porosity 95%, but different microstructures resulting from different pH during synthesis. For a base-catalyzed aerogel, the temperature dependence of the shape of adsorption isotherms and of the morphology of the condensation process show evidence of a disorder induced transition,in agreement with recent theoretical predictions. This transition is not observed for a neutral-catalyzed aerogel, which we interpret as due to a larger disorder in this case.

Domaines: Matière Molle [cond-mat.soft]

Thierry Lambert, Florence Despetis, Laurent Puech, Pierre-Etienne Wolf. Evidence for a disorder induced phase transition in the condensation of 4He in aerogels. 2006. ⟨hal-00021285v2⟩