Analysis of Sans from Controlled Pore Glasses

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Abstract
Small angle neutron scattering measurements have been performed on several samples of silica controlled pore glasses with pore sizes ranging from roughly 7 to 30 nm. The scattering intensity is strongly peaked at small Q and shows approximate Porod law behavior at large Q. Contrast variation measurements have shown that the pore space in these samples is entirely interconnected and thus forms a bicontinuous microstructure. The scattering data have been analyzed using the leveled wave method based on an early scheme for representing two-phase microstructures resulting from spinodal decomposition. In this approach interfaces are modeled by the contours of a stochastic standing wave composed of plane wave components propagating in random directions with random phases and having wave numbers distributed according to a given probability density, P(k). We have determined model P(k) functions by fitting the SANS data with the leveled wave scattering function and then used these to construct leveled wave images of the corresponding porous structures. The average pore sizes obtained by measuring chord lengths in the computer models turn out to agree with the values determined for these glasses by mercury porosimetry.