SOME ASPECTS OF THE ELECTRICAL AND THERMAL-PROPERTIES OF AMMONIUM HYDROGEN TARTRATE

The relative permittivity (epsilon) and the electrical resistivity (rh o) were measured at varying temperature from 310 up to 490 K for polyc rystalline samples of ammonium hydrogen tartrate (AHT), NH4HC4H4O6. Th e measured parameters revealed that the compound undergoes successive solid-state structural phase transitions at similar to 368 K, 428 K an d similar to 473 K, in addition to a probable change in the conduction mechanism at similar to 333 K. A differential thermal analysis (DTA) thermogram and a thermogravimetric analysis (TGA) plot were also perfo rmed from room temperature (similar to 300 K) up to the melting point. The DTA results strongly support the existence of the above-mentioned solid-state phase transitions, whereas the TGA plot indicates the abs ence of any actual loss in weight in the transition temperature region s.The data are correlated to the reorientational motion of the NH4+ io n, combined with the arrangement of the molecules in their crystals an d in particular the hydrogen bonding system.