Globally Anisotropic High Porosity Silica Aerogels

Abstract

We discuss two methods by which high porosity silica aerogels can be engineered to exhibit global anisotropy. First, anisotropy can be introduced with axial strain. In addition, intrinsic anisotropy can result during growth and drying stages and, suitably controlled, it can be correlated with preferential radial shrinkage in cylindrical samples. We have performed small angle X-ray scattering (SAXS) to characterize these two types of anisotropy. We show that global anisotropy originating from either strain or shrinkage leads to optical birefringence and that optical cross-polarization studies are a useful characterization of the uniformity of the imposed global anisotropy.

18 pages, 14 figures, submitted to Journal of Non-Crystalline Solids

References in corpus (2)

• Helium-Three in Aerogel
• Acoustic Spectroscopy of Superfluid 3He in Aerogel

Cited by in corpus (7)

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• Anomalous Thermal Hall Effect in Chiral Phases of ${}^3$He-Aerogel
• Disorder Induced Anomalous Thermal Hall Effect in Chiral Phases of Superfluid ${}^3$He
• Superfluid Phase Stability of ${}^3$He in Axially Anisotropic Aerogel