Upper: Schematic representation of the system assembled for studies in an electrical field. Lower: a representation of the light-scattering cell.
Curves as functions of the intensity of electrical field: (a) current x EF; (b) light-scattering x EF; (c) normalized current x EF; (d) normalized light-scattering intensity x EF.
Difference between normalized electrical current x EF and normalized scattered intensity x EF curves, from data of Fig. 2.
Electrical current vs. time: (a) constant humidity and (b) slow dehydration of the hydrated silica by dry air flow (1 L min−1), under constant electrical field (375 V mm−1).
Averaged curves and kinetics of dehydration of silica samples during dehydration with a flow of dry air (1 L min.−1, 298 ± 1 K) under constant electrical field: (a) SG1; (b) SG2, and (c) SG3. The electrical current peaks correspond to the capacitive current, characteristic of the shifting of the electrodes after the weighing of the system (cell + silica).
Correlation curves between the relative humidity inside the cell and the current for silica samples. These experiments were started with the samples hydrated to equilibrium (RH = 74% and T = 298 K).
Curves of light-scattering intensity and current as functions of the dehydration time, under constant electrical field and dry air flow (375 V mm−1 and 1 L min−1): (a) SG1; (b) SG2, and (c) SG3.
Model used to estimate van der Waals and capillary forces. Conditions: R = Xm/ 2; ϕ ∼ 0; r2 ≫ r1; D ≪ R.
Schematic representation of the three steps suggested for the charge transport process with hydrated sílicas.
Surface properties of the silica gel samples obtained by nitrogen adsorption curves using BET (Brunauer, Emmett and Teller) theory and TGA.
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