Ferroelastic property of LiNH4SO4 single crystals

We have investigated the ferroelastic properties by stress in LiNH4SO4 single crystals grown by a slow evaporation method. The temperature dependence of the stress-strain hysteresis was also studied. From this result, it was determined that the LiNH4SO4 single crystal undergoes a phase transition near T-C = 11.5 degrees C. Also, the shapes of the stress-strain curves in phase III are different from that of the phase II. It was confirmed that LiNH4SO4 crystals have ferroelastic characteristics in phase III by the stress-strain hysteresis and Aizu classification.