Temperature-stable Barium Titanate Ceramics Containing Niobium Pentoxide

Abstract

Niobium is known to lower the Curie point and broaden the permittivity peak of barium titanate. However, the distribution of niobium in sintered barium titanate is often not homogeneous, being influenced by such preparation variables as large cation/small cation stoichiometry and firing conditions. In addition to these factors, it was found that, at least up to about 5 mol% Nb, the distribution of niobium in the barium titanate grains could be regulated by small amounts (<1 mol%) of oxides of Co, Mg, Ni or Mn. These oxides appear to form niobates that produce high permittivity solid solutions in the “skins” of the barium titanate grains and permit dielectrics to be obtained with permittivity (K≃¯2000), stable to within ±10% over the temperature range −55℃ to 125℃.