Microstructure and properties of lead ferroniobate ceramics (Pb(Fe 0.5Nb 0.5)O 3)

Abstract

Pure, single phase stoichiometric Pb(Fe 0.5Nb 0.5)O 3 (PFN) powders were successfully formed by molten salt synthesis using a mixture of NaCl and KCl salts. The sinterability and changes in microstructure of these powders, and the dielectric properties of sintered samples, were studied for both pure PFN and PFN with additives such as PbO and Li 2CO 3. The dielectric properties were sensitive to specimen density, the type of additive and the amount of additive. Pure PFN specimens, which were sintered at 1100 °C for 13 h, exhibited high dielectric constant values (12 270 at 1 MHz). PFN ceramics sintered with PbO as an additive showed inferior dielectric properties, although PbO served as a sintering aid and increased the specimen density. The dielectric properties of PFN with Li 2CO 3 additive are promising, because they exhibit both high dielectric constant values (14 000 at 1 MHz) and low values of d.c. conductivity. The improved dielectric properties with the addition of Li 2CO 3 might be attributed to the substitution of Fe by Li.