Investigation of the Ferroelectric to the Antiferroelectric Transition in LiNH₄SO₄by the ESR of ·NH₃⁺

Abstract

The electron spin resonance (ESR) of the NH 3 + free radical has been used to investigate the ferroelectric to the antiferroelectric transition in LiNH 4 SO 4 crystals. A sharp transition at 286 K was detected by ESR in the form of line-splitting. The NH 3 + free radical in the ferroelectric phase splits into two inequivalent species with different reorientational characteristics below the transition temperature. Twinning was simultaneously detected at the transition.