Abstract
The dielectric behavior of (Pb1−x/2Lax)(Zr0.9Ti0.1)O3 PLZT 100x/90/10 (0≤100x≤1) was studied in the frequency range 102–1014 Hz using dielectric, time-domain terahertz (THz), far-infrared, and Raman spectroscopy in the temperature interval 10–900 K. PZT 90/10 and PLZT 2/90/10 undergo two phase transitions, from a cubic paraelectric to a rhombohedral untilted ferroelectric (FE) phase and on further cooling to a tilted FE phase. PLZT 4/90/10 and PLZT 10/90/10 are incommensurately modulated and composed of an intergrowth of polar and antipolar cation displacements. These samples consequently demonstrate a FE soft mode which exhibits minimal frequency several tens of degrees above the nominal antiferroelectric phase transition temperature. The dielectric response of PLZT 100x/90/10 is mainly governed by a gigahertz relaxation and a soft phonon component in the THz range. As in other PbO-based perovskites, the soft mode is split into a higher-frequency component (ω∼80 cm−1) and a highly damped THz component (ω∼30 cm−1), with larger dielectric strength already in the paraelectric phase.
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