Phase transitional ferroelectric like behaviour of ammonium tetroxalate dihydrate single crystal

Abstract

Dielectric characterisation on ammonium tetroxalate dihydrate (ATOXAL) single crystal has been carried out. The dielectric constant and dielectric loss studied as a function of temperature and frequency have been found to have anomalous variations in the vicinity of the phase transitions at 100 °C and 140 °C which have been duly supported by thermal studies. An Arrhenius shift in the temperature variation of relaxation frequency has estimated the activation energy and the means of conduction. The ferroelectric and paraelectric phase activation energies have been determined to be 1.772 eV and 3.477 eV, respectively. The Penn band gap is 1.892 eV and the polarizability has been evaluated. The piezoelectric coefficient d₃₃ has been found to be 1.5 pCN^-1. The ferroelectric hysteresis behaviour has been investigated at room temperature. From the hysteresis loop it is found that the grown crystal exhibites a remanent polarization (P_r) ∼ 0.367 μC/cm², saturation polarisation (P_s) ∼ 1.789 μC/cm² and coercive field (E_c) ∼ 6.599 kV/cm.