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Ionic transport in silica xerogels investigated by dynamic current-voltage characteristics

Sodolski H., Grygiel P., Tomaszewicz W.

Optica Applicata

2003

Vol. 33, nr 1

83-89

The essence of the dynamic current-voltage characteristics (DCVCs) method is the application of linearly changing voltage to a sample with a plane-parallel electrode system. Previous theoretical considerations have shown that the method may be applied to low thermal conductivity materials, e.g., SiO2 porous xerogels, in order to investigate ionic transport therein. The low thermal conductivity of SiO2 xerogels entails a high temperature gradient occurring when DCVCs are measured in vacuum at elevated temperatures. Therefore, it is possible to deduce the sign and mobility of ions responsible for electrical conductivity inside the materials from the characteristic shape of DCVCs

Thermally stimulated currents in silica xerogels with temperature gradient.

Sodolski H., Tomaszewicz W.

Optica Applicata

2000

Vol. 30, nr 4

543-551

Presents results obtained by the application of the method of thermally stimulated depolarization (TSD) to investigate dipole relaxation in SiO/sub 2/ xerogels. The presence of a strong temperature gradient in the sample has been revealed during measurements of the TSD current. The paper describes the method of determination of activation energy W, initial polarization P/sub 0/ and factor tau /sub 0/, for the dipole relaxation processes under investigation. It has been shown that the modified TSD method is a sensitive tool for the investigation of changes taking place in the peripheral molecular layer on the surface of pores in SiO/sub 2/ xerogels.