An EPR study of local fluctuations in the vicinity of the ferroelectric phase transition in Li2Ge7O15

EPR spectra of Mn²⁺ ions have been studied in the temperature interval containing the ferroelectric transition in crystalline lithium heptagermanate Li₂Ge₇O₁₅. The EPR linewidth and shape were measured as functions of temperature and orientation. It is shown that the critical resonance-line broadening observed to occur in the vicinity of the phase transition is due to fluctuations in the local order parameter with frequencies below 10⁷ Hz.