Central-Peak Components and Polar Soft Mode in Relaxor PbMg1/3Nb2/3O3 Crystals

摘要: Dielectric response of relaxor PMN single crystals was investigated in a broad frequency range 100 Hz–100 THz by combination dielectric spectroscopy (100 Hz–1 GHz, 10–700 K), time-domain and infrared (IR) reflectivity (5–3000 cm−1, 10–300 K). Polar TO1 phonon (soft mode) is resolved IR spectra at all temperatures studied, follows the Cochran law softens towards Burns temperature on heating. The central mode (dielectric relaxation) splits below room into two components. First one appears assigned as activated density states due to breaking local symmetry consequence polar nano-clusters. Second relaxation originates from cluster breathing flipping. It anomalously broadens cooling leads frequency-independent loss between GHz 200 K non-ergodic phase.