Anomalous transverse acoustic phonon broadening in the relaxor ferroelectric (formula presented)

The intrinsic linewidth (formula presented) of the transverse acoustic phonon observed in the relaxor ferroelectric compound (formula presented) (PMN-20%PT) begins to broaden with decreasing temperature around 650 K, nearly 300 K above the ferroelectric transition temperature (formula presented) We speculate that this anomalous behavior is directly related to the condensation of polarized, nanometer-sized, regions (PNR) at the Burns temperature (formula presented) We also observe the “waterfall” anomaly previously seen in pure PMN, in which the transverse optic branch appears to drop precipitously into the TA branch at a finite momentum transfer (formula presented) The waterfall feature is seen even at temperatures above (formula presented) This latter result suggests that the PNR exist as dynamic entities above (formula presented).