Phase transitional ferroelectric like behaviour of ammonium tetroxalate dihydrate single crystal

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 (Pr) ∼ 0.367 μC/cm2, saturation polarisation (Ps) ∼ 1.789 μC/cm2 and coercive field (Ec) ∼ 6.599 kV/cm

Influence of L-Lysine as dopant in ammonium tetroxalate dihydrate– spectral, optical, thermal, mechanical and dielectric properties

Semi organic crystals offer a variety of molecular structures by virtue of the changes brought out in selection of dopants. In the present work mechanical, thermal, dielectric, FTIR and UV studies of single crystals of ammonium teroxalate dihydrate (ATOXAL) doped with basic amino acid L-Lysine have been studied and compared. Fourier transform infrared (FTIR) spectroscopy study confirms the incorporation of L-Lysine into ATOXAL. Optical studies on L-Lysine doped ATOXAL (L-Lys doped ATOXAL) crystals reveal that these crystals are optically better and more transparent than the pure ones having wide transmission spectra lying in the entire visible and near infrared (NIR) regions. Optical band gap has been found to be 4.281 eV and the nonlinear index of refraction is 1.829. Negative photoconductivity has been exhibited by the crystal. TG / DTG and DSC analyses reveal that thermal anomalies occurr at 111.1 °C and 231.8 °C. Low dielectric constant and dielectric loss at higher frequency observed in L-Lys doped ATOXAL is a desirable property to enhance the NLO efficiency. Also, it is observed from the dielectric studies that the ferroelectric phase has higher activation energy than the paraelectric phase. Vickers’s micro hardness test reveals that dopant inclusion increased the mechanical strength of the crystals

Phase transitional ferroelectric like behaviour of ammonium tetroxalate dihydrate single crystal

875-883Dielectric 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 (Pr) ∼ 0.367 μC/cm2, saturation polarisation (Ps) ∼ 1.789 μC/cm2 and coercive field (Ec) ∼ 6.599 kV/cm

Influence of L-Lysine as dopant in ammonium tetroxalate dihydrate– spectral, optical, thermal, mechanical and dielectric properties

444-452Semi organic crystals offer a variety of molecular structures by virtue of the changes brought out in selection of dopants. In the present work mechanical, thermal, dielectric, FTIR and UV studies of single crystals of ammonium teroxalate dihydrate (ATOXAL) doped with basic amino acid L-Lysine have been studied and compared. Fourier transform infrared (FTIR) spectroscopy study confirms the incorporation of L-Lysine into ATOXAL. Optical studies on L-Lysine doped ATOXAL (L-Lys doped ATOXAL) crystals reveal that these crystals are optically better and more transparent than the pure ones having wide transmission spectra lying in the entire visible and near infrared (NIR) regions. Optical band gap has been found to be 4.281 eV and the nonlinear index of refraction is 1.829. Negative photoconductivity has been exhibited by the crystal. TG / DTG and DSC analyses reveal that thermal anomalies occurr at 111.1 °C and 231.8 °C. Low dielectric constant and dielectric loss at higher frequency observed in L-Lys doped ATOXAL is a desirable property to enhance the NLO efficiency. Also, it is observed from the dielectric studies that the ferroelectric phase has higher activation energy than the paraelectric phase. Vickers’s micro hardness test reveals that dopant inclusion increased the mechanical strength of the crystals