Linking ionic conductivity and piezoelectric resonance in KTiOPO4

The interplay between the ionic conductivity and the ferroelectric polarization is a key point for understanding and tuning the properties of KTiOPO4 (KTP) single crystals. We show here that the piezoelectric resonance undergoes a well-defined splitting at 200 K for several KTP samples exhibiting different geometries, crystalline orientations, and ferroelectric domain states. This method is a powerful way for probing the buildup of ionic space charges when the ionic conductivity stops to screen the ferroelectric polarization. We also show that it is useful to track the evolution of this space charge under several thermal and moderate electrical stresses.