Effect of sintering atmosphere on the dielectric properties of barium titanate based capacitors

It has been found that BaTiO3 based capacitor compositions containing lithium tetraborate (flux) and bismuth oxide (flux and Curie peak suppressor) can be fired in an inert (argon) atmosphere without sacrificing densification. However, the inert atmosphere firing can lead to a dramatic increase of both the dielectric constant and dissipation factor of the samples containing bismuth oxide which can be suppressed by adding a small amount of manganese dioxide in the compositions. The temperature coefficient of capacitance of such samples shows the desirable flattened response when fired in argon atmosphere. The observations have been explained by considering the formation of defects at elevated temperatures in bismuth containing samples when fired in an inert atmosphere.