Hysteresis in the rhombohedral–orthorhombic phase transition of KNbO3 under inhomogeneous strain

The influence of the heating rate on the low temperature phase transition (PT) of the piezoelectric crystal potassium niobate (KNO) was studied by micro-Raman spectroscopy. It is found that crystallographic defects are more important than the heating rate for the onset of the PT. If the strain shifts the transition temperature (TT) from the rhombohedral to the orthorhombic phase to lower values, then it also shifts the reverse PT to higher temperatures. The PT on heating is more sensitive to the rate than the PT on cooling.

► The low temperature phase transition of KNbO3 was studied by Raman spectroscopy.
► Crystallographic defects are more important than the heating rate.
► The strain changes the thermal hysteresis width.
► The strain does not change the average transition temperature.
► The phase transition on cooling is less sensitive to the rate.