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

Kirupavathy, Dr. S. Shahil ; Jerusha, Eunice ; Shalini, S


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.


Solution growth; Optical;Thermal; Dielectric;Microhardness

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