Electrical properties and infrared spectra of LiNH4SO4 between 4 and 300 K

A new phase transition at 258K is suggested by a weak anomaly of the dielectric constant without modification of the infrared spectra for ν > 10 cm-1. It should be a polar-polar phase transition like in the 285 K well-known transition.On the opposite, another phase transition is found from modification in the infrared spectrum between 4 and 80 K, without significant change of the static dielectric constant.