Structures and dielectric properties of Pb(Fe <inf>1/2</inf>Nb <inf>1/2</inf>) <inf>1-x</inf> Ti <inf>x</inf>O <inf>3</inf> single crystals

Abstract

The structures and dielectric properties of Pb(Fe 1/2Nb 1/2) 1-x Ti xO 3 (PFNT, x = 0:07 and 0.48) single crystals were investigated using a combination of temperature-dependent dielectric, X-ray diffraction (XRD), Raman, and X-ray absorption fine structure (XAFS) spectra. Detailed structure analyses reveal that the crystal structure of PFNT (x = 0:48) is single-phase tetragonal perovskite, whereas that of PFNT (x = 0:07) is a mixture of rhombohedral and tetragonal phases. The structural differences are found to have significant connections with the dielectric properties in the temperature range of 90-300 K. Both samples exhibit a frequency-dependent dielectric anomaly, arising primarily from the 3d electrons hopping between Fe2+ and Fe3+. The second dielectric anomaly, which is a weak frequency dispersion and observable only for PFNT (x = 0:07), was probably caused by a dipole glass behavior near the morphotropic phase boundary. © 2012 The Japan Society of Applied Physics.