Influence of cooling mode on the electrical properties and microstructure of Ba1.022−xSmxTiO3 ceramics sintered in a reducing atmosphere

We investigated the effects of the Sm-dopant content and the cooling rate on the electrical properties and microstructure of Ba1.022−xSmxTiO3 (BST) ceramics, which were sintered at 1200 °C for 30 min in a reducing atmosphere and then reoxidized at 800 °C for 1 h. The results indicated that the cooling rate affected the electrical properties and the microstructure of the BST samples, whose room-temperature resistivity increased with increasing cooling rate. The semiconducting BST ceramics showed a pronounced positive temperature coefficient of resistivity effect, with a resistance jump greater by 3.16 orders of magnitude, along with a low room-temperature resistivity of 157.4 Ω cm at a cooling rate of 4 °C/min. The room-temperature resistivity of the specimen was lower after sintering for 30 min at 1150 °C during cooling.