Dielectric and ageing behaviour of strontium barium niobate with barium strontium titanate additives

The dielectric properties and ageing behaviour of (1-y)(Ba0.6Sr0.4Nb2O6)-y(Ba0.6Sr0.4TiO3) ceramics have been studied. A single phase compound is obtained for y <= 0.3 as judged from the x-ray diffraction spectra. With the addition of BST, the maximum dielectric constant is increased and the dielectric loss is reduced. The dielectric curves become broader. The abnormal grain growth that is usually observed in Ba0.6Sr0.4Nb2O6 has also been suppressed by the addition of B0.6S0.4TiO3. The Curie temperature decreases with increasing amounts of BST added and all samples obey the Curie-Weiss law above the Curie temperature. The ageing behaviour of the ceramics is studied and an oxygen vacancy inducing the dielectric ageing mechanism is used to explain the observed results.