Hypersonic and dielectric anomalies of (Pb(Zn1/3Nb2/3)O3)0.905(PbTiO3)0.095 single crystal

Abstract

Both the longitudinal (LA) Brillouin backscattering spectra and dielectric permittivities along the [001] direction have been measured as a function of temperature for relaxor-ferroelectric single-crystal (Pb(Zn1/3Nb2/3)O3)0.905(PbTiO3)0.095 (PZN-9.5%PT). A sharp ferroelectric phase transition (which is associated with a sharp Landau-Khalatnikov-like phonon damping maximum) was observed near 460 K. As the temperature decreases, a diffuse phase transition (which is associated with a broad acoustic phonon damping maximum) was detected near 340 K. This broad damping evolution is attributed to dynamic order-parameter fluctuations. In addition, the nature of the thermal hysteresis for the dielectric permittivity confirms that these transitions (near 340 and 460 K) are diffuse first order and first order, respectively. The frequency-dependent dielectric data ɛ′′c(f,T) prove the existence of an electric dipolar relaxation process below 360 K. The activation energy, the Vogel-Fulcher temperature, and attempt frequency corresponding to this relaxation process are also calculated.