Dielectric Properties Dependence on Residual Sodium and Potassium Content in Silica Xerogels

Abstract

ABSTRACTAs sodium and potassium are removed from silica xerogels through leaching, the dielectric properties of gels are significantly altered. Work has been done to relate the magnitude of the change in alkali ion content to the change in dielectric properties. Gels were prepared through a colloidal processing method and leached in ammonium nitrate, nitric acid, and water to reduce, to different degrees, the content of sodium and potassium ions. Atomic absorption (AA) was used to determine the actual sodium and potassium content of each gel after its capacitance and dielectric loss were measured as a function of frequency. All electrical measurements were carried out at room temperature and constant humidity. At least three samples for each leaching treatment were evaluated. Data obtained shows a definite relationship between the sodium and potassium content measured by AA and the dielectric constant.