Investigations on the growth and characterisation of an isomorphous ammonium tetroxalate dihydrate superacid crystal

Single crystals of ammonium tetroxalate dihydrate (ATOXAL) were grown by the slow evaporation solution growth technique. The crystal structure was confirmed by single crystal XRD analysis. The functional groups present were explored and ammonium ion reveals its group frequency at 1404 cm−1 and 1489 cm−1 respectively from the recorded FT-IR and FT-Raman spectra. Microhardness studies were carried out with the Vicker's microhardness tester. The TG, DTA and DSC studies divulged information about thermal behaviour. The HOPM studies supported the thermal anomalies in the crystal. The density was evaluated to be 1.639 g/cc. The optical behaviour was examined with DRS, UV–vis, photoluminescence and photoconductivity studies. The optical band gap was assessed to be 3.963 eV. Negative photoconductivity was exhibited. SEM micrographs showed the purity and crystalline nature of the grown crystals. Dielectric anomalies are seen in the variation of the dielectric constant with temperature suggesting the ferroelectric nature of the crystal.