Tuning the Dielectric Properties of Individual Clay Nanosheets by Interlayer Composition: Toward Nano‐Electret Materials

Abstract

To exploit the full potential of clays for electronic applications, a deeper understanding of how their dielectric properties can be tuned in a defined manner is essential. So far, most attention has been paid to the surface chemistry of clay platelets and their mechanical properties. Important properties, like electrical breakdown voltages, have been studied only on the macroscopic scale and not on the level of single platelets. One open important question that must be addressed is how far the dielectric properties, such as the breakdown characteristics, can be tuned by the composition of the interlayer. By using scanning probe techniques, it became possible to study individual platelets of the synthetic hectorite. Their interlayer composition is varied by encapsulating different cations between the silicate monolayers, besides sodium, ammonium, and an organic dye. The electrical breakdown characteristics of the monolayers and functional double stacks of hectorite are determined at the single platelet level. The use of these clay‐based materials as electrets is evaluated by creating defined charge patterns at the nm‐level and recording their isothermal potential decay. Thereby, the charge retention properties of the different clay compounds are determined.