Mm. Abdelkader et al., NONFERROELECTRIC PHASE-TRANSITIONS IN POTASSIUM HYDROGEN SULFATE [MERCALLITE, KHSO4], Materials research bulletin, 29(3), 1994, pp. 317-325
Accurate measurements of some electrical properties combined with the
differential thermal analysis (DTA) were made from room temperature up
to 200-degrees-C for single crystals of KHSO4 (KHS). The data reveal
the existence of two (non-ferroelectric) phase transitions around 100-
degrees-C and 175-degrees-C. The first structural phase transition may
involve only minor change in atomic positions and therefore it is not
easy to detect. The existence of this phase is confirmed by the X-ray
diffraction pattern. The data are correlated with the arrangement of
the molecules in the unit cell including the hydrogen bonding system d
ue to the two distinct HSO4 ions as well as the onset of the reorienta
tional motion of the sulphate group.