A calcining at 3000C and smtering process were proposed to obtain a pure perovskite phase Pb(Fel/2 Nbl/2)O3 from a 4PbO/Nb205/Fe203 mixture, which is calcined at 300Β°C for several days and sintered at various temperatures for 2h; the resultant powder was air quenched. The X-ray powder diffraction pattern of the sintered sample is carefully analyzed to ider~ify intermediate phases. The effects of calcining at 3000C and sintering on obtaining PFN are based on the deformation of PbsFe4Nb4021. A reaction mechanism for the calcining cycle of Pb(Felr2 Nbl/2)O3 is proposed.
1-INTRODUCTION
Lead based ferroeleetrics with a general formula of Pb(B1B2)O3, have been developed as a low-firing multilayer capacitor materials [1-3].
In particular, Pb(Fel/2 Sbl/2)O3 (here after refered to as (PFN) has been widely used as one of the important constituents in multilayer ceramic capacitors, since it shows high dielectric constants (>104 ) even with sintering temperature as low as 1000Β°C [4-5].
However, it is well known that the perovskite PFN phase is not directly synthesized by a simple reaction between mixed oxides, but by complex reactions between intermediate products (e.g. Pb3Nb4013 and Pb2Nb2OT)