Barrier layer formation and PTCR effect in (1-x)   Pb(Fe1/2Nb1/2)O3]-xPbTiO3 (x = 0.13) ceramics
  (1-x)Pb(Fe1/2Nb1/2)O3-PbTiO3(PFN-xPT)Ceramics with x = 0.13 sintered at 1473K show diffuse phase transition and very high dielectric constant at lower frequencies.The high value of dielectric constant at lower frequencies is shown to be due to the barrier layer formation.The resistivity of the PFN-xPT ceramics, obtained by complex impedance analysis, initially decreases with temperature and then shows an upward trend beyond the ferroelectric Curie point reminiscent of BaTiO3 based thermistors with PTCR effect. 
Satendra Pal Singh, Akhilesh Kumar Singh and Dhananjai Pandey