Evidence for a disorder driven phase transition in the condensation of 4He in aerogels
Abstract
We report on thermodynamic and optical measurements of the condensation process of 4He in three silica aerogels of different microstructures. For the two base-catalysed aerogels, the temperature dependence of the shape of adsorption isotherms and of the morphology of the condensation process show evidence of a disorder driven transition, in agreement with recent theoretical predictions. This transition is not observed for a neutral-catalysed aerogel, which we interpret as due to a larger disorder in this case.
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