Mechanical and Dielectric Energy Loss Related to Viscous Motion and Freezing of Domain Walls

Abstract: Three dielectric loss @) andlor three mechanical loss (Q-') peaks (Pl,P2,P3) and corresponding susceptibilities for ferroelectric KDP and TGS, and ferroelastic LNPP crystal and Cu-Al-Zn-Ni alloy have been investigated in the kHz range. P1 and P2 almost overlap for first order phase transitions. PI, a very narrow peak, is attributed to the dynamic domains due to fluctuations near Tc. P2 is recognized to be related to domain walls (DWs). The formulas of Q " and D caused by the viscous motion of DWs are derived, being fairly coincident with the experimental data of P2. The viscous &cient, pinning force constant of DW and the spontaneous shear strain have been calculated for Cu-Al-Zn-Ni. The mwptibility, s ' or WJ, always shows a high plateau below Tc and drops down rapidly nearly consistent with the low temperature side of P3 peak for polydomain TGS, KDP and Cu-Al-Zn-Ni. P3 is thought to originate from the freezing of DWs of high density due to a collective pinning of randomly distributed defects, similar to the pinned-vortex glass model suggested for high TC superconductors. 1