Abstract:
This study employs resonant ultrasound spectroscopy to investigate the elastic properties of single crystalline KH2PO4 (KDP) through the paraelectric to ferroelectric phase transition. Noteworthy anomalies are observed in selected resonance modes and their corresponding mechanical quality factors (Q-1) around the transition temperature. The thermal evolution of elastic constants (Cij) across the phase transition reveals a significant softening and stiffening behavior. The anomalous behavior of all elastic constants (Cij) across the phase transition suggests the involvement of higher -order coupling between the lattice and polarization in the KDP crystal. Furthermore, the bulk modulus (B) undergoes a sudden softening precisely at the transition, while the shear modulus (G) initially softens and subsequently stiffens across the transition.