材料期刊网

The structures and dielectric properties of Pb(Fe1/2Nb1/2)(1-x)TixO3 (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. (C) 2012 The Japan Society of Applied Physics