DIELECTRIC, ELASTIC AND PIEZOELECTRIC PROPERTIES OF LI2B4O7 SINGLE-CRYSTALS IN THE TEMPERATURE-RANGE FROM 4-K TO 900-K

Dielectric, elastic and piezoelectric measurement was performed on Li2B4O7 in the temperature range from 4 K to 900 K. Superionic properties along the c-axis above 400 K were reconfirmed by dielectric measurement. Temperature dependences of the elastic compliance coefficients s11 and s22, the elastic stiffness constant C33, and the piezoelectric constants d31, d32 and d33 were measured by the piezoelectric resonance-antiresonance method. Elastic anomalies were found at 375 K in both s11E(s11D) and s22E(s22D), while no anomaly was found in c33E(c33D). Piezoelectric constant d31 showed a tiny steplike anomaly and d32 exhibited a peak at 375 K, whereas no anomaly was found in d33. These elastic and piezoelectric anomalies are concluded to be caused by a phase transition.