The intrinsic linewidth ΓTA of the transverse acoustic phonon observed in the relaxor ferroelectric compound Pb (Mg1/3Nb2/3)0.8Ti0.2O3 (PMN-20%PT) begins to broaden with decreasing temperature around 650 K, nearly 300 K above the ferroelectric transition temperature Tc (∼360 K). We speculate that this anomalous behavior is directly related to the condensation of polarized, nanometer-sized, regions (PNR) at the Burns temperature Td. 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 qwf∼0.15 Å-1. The waterfall feature is seen even at temperatures above Td. This latter result suggests that the PNR exist as dynamic entities above Td.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Apr 1 2002|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics