ELECTRICAL PROPERTIES OF BARIUM TITANATE CO- DOPED WITH Nb AND Mn

Abstract

A modified Pechini process was used to prepare nanopowders of barium titanate (BT) co-doped with niobium and manganese. Prepared BT compositions were (1) BT doped with 0.4 mol% Nb and 0.1 mol% Mn (BT1); (2) 0.4 mol% Nb and 0.05 mol% Mn (BT2) and (3) 0.8 mol% Nb and 0.01 mol% Mn (BT3). The XRD results of sintered samples showed the formation of barium titanate tetragonal crystal structure. Microstructure was consisted of polygonal grains but the differences in the grain size, homogeneity and porosity between the doped ceramics were noticed. The addition of dopants influenced the grain size and microstructure development. The dielectric measurements of all ceramics showed the behavior of classical ferroelectric material. In comparison with pure barium titanate, structural transition of all co-doped ceramics are shifted to lower temperatures. The real permittivity value increase in all co-doped ceramics in the whole frequency range, reaching much higher values then in pure barium titanate ceramics obtained by polymeric precursors method. The analysis of impedance spectrum at higher temperatures showed the presence of both, grain interior and grain boundary effects.