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

The relative permittivity (epsilon) and the electrical resistivity (rho) were measured at varying temperature from 310 up to 490 K for polycrystalline samples of ammonium hydrogen tartrate (AHT), NH4HC4H4O6. The measured parameters revealed that the compound undergoes successive solid-state structural phase transitions at similar to 368 K, 428 K and 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 performed 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 absence of any actual loss in weight in the transition temperature regions. The data are correlated to the reorientational motion of the NH4+ ion, combined with the arrangement of the molecules in their crystals and in particular the hydrogen bonding system.