Effect of the Moisture Content on the Electrical Conductivity of SiO2/LiCl Xerogels

The effect of LiCl and water in pores on the active component of the low-frequency electrical conductivity of silicon dioxide xerogels is investigated. It is found that the electrical conductivity of SiO₂/LiCl xerogels at atmospheric humidity substantially depends on the hygroscopic properties of the salt. It is demonstrated that the dependence of the electrical conductivity of SiO₂and SiO₂/LiCl xerogels on the fraction pof the pore volume filled with an ionic conductor (water or an aqueous LiCl solution) can be described by equations of the percolation theory. The dilution of the LiCl solution upon water sorption does not change the character of the power dependence (p). It is shown for the first time that the introduction of water into pores considerably (by several orders of magnitude) extends the electrical conductivity range for xerogels and shows promise as a means for increasing the sensitivity of humidity detectors and controlling their threshold response.