Elastic constants and high-temperature elastic anomalies near 425 K in lithium hydrazinium sulfate

Abstract

All the nine elastic constants of the orthorhombic crystal lithium hydrazinium sulfate, Li(N2H5)SO4, have been determined by measuring ultrasonic velocities using pulse echo overlap technique at 10 MHz. Temperature variation of all the six diagonal elastic constants and the three off-diagonal combinations have been measured between 300 and 450 K. Some of the constants show anomalous behavior in the 410–440 K temperature region, which is attributed to a phase transition in the crystal near 425 K. Magnitude of the velocity anomaly is comparatively small. A new high-temperature ultrasonic bond material suitable for transverse waves is also reported.