DC electrical conductivity and phase transitions in (NH4)3H(SO4)2

Abstract
Four distinct peaks are observed at 140, -26, -132 and -140 degrees C in the sigma x* against T-1 plot between 200 and -196 degrees C for (NH4)3H(SO4)2, corresponding to four different phase transitions of which the one at -26 degrees C is reported here for the first time. Data on doped samples reveal the charge transport mechanism in the crystal.