Infrared spectrum of ferroelectric lithium hydrazinium sulphate [Li (N₂H₅) SO₄]

Abstract

Dielectric observations on lithium hydrazinium sulphate have shown earlier that it is ferroelectric over a range of temperatures from below -15° C. to above 80°C. and a new type of hydrogen bond rearrangement which would allow the protons to migrate along the chain has also been suggested by others. The infrared spectrum of LiH₂S in the form of mull and as single crystal sections parallel and perpendicular to the 'C' axis exhibit about 21 well-defined absorption maxima. The position and the width of the maxima agree with the known structure of the crystal according to which the hydrazine group exists in the form of the hydrazinium ion, NH₂·NH₃⁺ and the observed N⁺-H frequencies agree better with the new correlation curve given by R. S. Krishnan and K. Krishnan (1964). However it has been pointed out that from a comparative study of the new infrared spectra of hydrazonium sulphate and lithium ammonium sulphate that the absorption band at 969 cm.^-1 is due to N-N stretching vibration and that the fairly intense band between 2050–2170 cm.^-1 is due to the bending vibrations of the NH₃⁺ group.