Electrical conductivity and dielectric constant measurements on Na 2CO 3·H 2O crystals

Abstract

The d.c. electrical conductivity and dielectric constant at 100 KHz of Na 2CO 3·H 2O crystals grown at 40±1°C have been measured in the temperature range 30–720°C. It has been observed that the conductivity shows a peak at 150°C. It also shows changes at 220, 360, 470 and 620°C. The dielectric constant measurement also shows a peak at 160°C and some changes at 190, 360, 480 and 620°C. The peaks in electrical conductivity and dielectric constant correspond to the dehydration process, the changes at 360 and 480°C to phase transformations and changes at 220 and 620°C to electrical transitions. The observed peaks in conductivity and dielectric constant measurements at the dehydration temperature have been explained on the basis of release of water molecules and the subsequent dissociation of some of these released water molecules into H + and OH − ions. Availability of these charged particles increases the conductivity, whereas the formation of space charge increases the dielectric constant.