The dielectric properties and electrical conduction of Ba1−xSrxTiO3 (x = 0.2, 0.25,

0.3) ceramics were investigated at 25 to 400C and 100Hz to 1MHz. The broad

dielectric peaks ε'(f), tanδ(T), tan δ(f) and the distribution parameter β were all

indicative of a typical relaxation behaviour existing above 200C for all

compositions. With increasing Sr content, more grain boundaries acting as

'electrical barriers led to the conductivity decreasing, and the activation energies of 0.88 to 0.96eV for different compositions indicated that the oxygen vacancies

acting as 'polarons' under the external ac electric field led to the relaxation

behaviour.

Relaxation Behaviour Induced by Oxygen Vacancies of Barium Strontium Titanate

at High Temperatures. Z.Li, H.Fan: Journal of Physics D, 2009, 42[7], 075415