ELASTIC AND DIELECTRIC STUDIES ON THE PHASE-TRANSITION OF FERROELECTRIC LITLC4H4O6-BULLET-H2O

Elastic and dielectric properties of ferroelectric LiTlC4H4O6.H2O (LTT) were studied in the paraelectric phase. The Curie-Weiss type anomalies were observed in the elastic stiffness constant at constant electric field, the free dielectric constant and the clamped dielectric constant, while no definite anomaly was found in the elastic stiffness constant at constant electric displacement. The phase transition of LTT is proper ferroelectric, in contrast to the case of isomorphic LiNH4C4H4O6.H2O (LAT) known as proper ferroelastic. The dielectric instability in LTT is consistently explained by the low-lying soft TO mode reported previously.