Dielectric properties of cobalt and chromium doped lead iron tungstate relaxer ceramics

The effect of Co and Cr doping on the dielectric properties of Pb(Fe2/3W1/3 )O-3 relaxor ceramics is analysed in this work. No second phases were detec ted for Co doped PFW for Co<7.5at%. On the other hand, a Pb2WO5 second phas e was identified in Cr doped PFW. Both Co and Cr decrease the permittivity maximum and shift transition temperature to high temperatures. Relaxer agin g behaviour was observed for both doped compositions, being more pronounced for Cr doped PFW. Oxygen annealing post-sintering treatment increases epsi lon(max) and the sharpening of temperature dielectric response of Cr doped PFW. The observed dielectric modifications are discussed in relation to the probable defects present in the ceramics.