Mechanical aging behavior of oriented Pb(Mg1/3Nb2/3)O-3-PbTiO3 and Pb(Zn1/3Nb2/3)O-3-PbTiO3 single crystals

The aging characteristics of < 001 > -oriented Pb(Zn1/3Nb2/3)O-3-PbTiO3 (PZ N-PT) and Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) single crystals have been studi ed under electrical and mechanical drive. A significant increase in hystere tic loss and decrease in piezoelectric constant were observed under continu ous excitation. Systematic investigations of piezoelectric aging were then performed using a novel mechanical fatigue method. Piezocrystals were place d between two magnetostrictive plates and clamped. Periodic longitudinal co mpressive stresses were generated by applying magnetic fields. At both shor t and long times, the piezoelectric constant was found to decrease slowly. However, in an intermediate range, a pronounced decrease was observed over a narrow time range. The dynamics of aging have been shown to scale to a hi erarchical relaxation process, typical of disordered systems such as random field and glassy states. (C) 2001 American Institute of Physics.