Effects of annealing treatment on the dielectric properties of manganese-modified Pb(Fe2/3W1/3)O-3 ceramics

The dielectric properties of thermally treated manganese doped Pb(Fe2/3W1/3 )O-3 (PFW) ceramics were investigated. Modifications of the dielectric prop erties by thermal annealing were observed. Air annealing causes a sharpenin g of the dielectric permittivity and an increase of the permittivity maximu m values, more pronounced as the amount of manganese dopant increases. Oxyg en annealing does not cause evident variations in the dielectric permittivi ty curve. The presence of oxygen vacancies is evinced by thermal gravimetri c measurements. The role of oxygen vacancies, as well as the associations o f manganese ions with oxygen vacancies, on the annealing process, is propos ed and discussed. (C) 1998 Chapman & Hall.