Dielectric anomalies induced by different mechanisms in   Pb(Fe1/2Nb1/2)1-xTixO3 single crystals
  We investigated the dielectric properties of Pb(Fe1/2Nb1/2)1-xTixO3 single crystals below room temperature. Two dielectric anomalies were detected in sample A while only one was detected in sample B in the temperature range 90~300 K. A Debye-like relaxation with strong frequency dispersion was detected in both samples. The pre-edge XAFS suggests that this dielectric anomaly is induced by the hopping conductivity between Fe2+ and Fe3+. The EXAFS results give us a clear picture of the local structure of iron ions. The weak frequency dependent dielectric anomaly only observed in sample A is supposed to be due to the dipole glass behavior. 
Kui Liu, Xinyi Zhang, Shiqiang Wei, H. Oyanagi, and Jingzhong Xiao