Effect of post sinter annealing on the dielectric constants of PMN and PFN

Lead magnesium niobate (PMN) and lead iron niobate (PFN) are the ferroelect ric ceramics having perovskite structure. Both of these compounds have high dielectric constant (10 000-20 000) and the change in their dielectric con stant with respect to temperature is gradual, showing diffused phase transi tion peaks at -12 degreesC (PMN) and 110C (PFN) respectively. The dielectri c properties of these compounds depend very much on their microstructural f eatures i.e. grain size, grain boundary thickness etc. In this study, the P MN and PFN powders prepared by semi-wet hydroxide route were sintered in Pb O atmosphere at 1000-1150 degreesC. The sintered pellets were heated in air at 1000 degreesC for 1/2 to 1 h. Their dielectric properties with respect to temperature were studied and the effect of post sinter annealing on thei r dielectric constants was analysed. (C) 2001 Elsevier Science Ltd and Tech na S.r.l. All rights reserved.