Effect of measuring atmosphere on the electrical properties of nanoporous (Ba,Sr)(Ti,Sb)O3 ceramics

Nanoporous (Ba,Sr)(Ti,Sb)O-3 ceramics were fabricated by the addition of partially oxidized Ti powder of 4 wt.%, corn- and potato-starch of 20 wt.% into the (Ba,Sr)(Ti,Sb)O-3 powder, respectively. The effect of measuring atmosphere on the electrical properties of the porous (Ba,Sr)(Ti,Sb)O-3 ceramics and the role of oxygen on the grain boundaries in the PTCR characteristics of the (Ba,Sr)(Ti,Sb)O-3 ceramics were investigated. The electrical resistivity of the porous (Ba,Sr)(Ti,Sb)O-3 ceramics was measured in the air, O-2, N-2 and H-2 atmospheres during heating and cooling cycles. It was found that the PTCR characteristics and room-temperature resistivity of the porous (Ba,Sr)(Ti,Sb)O-3 ceramics decreased in reducing atmosphere mainly because of the decrease in potential barrier height, whereas it increased in oxidizing atmosphere mainly because of the increase in potential barrier height. (C) 2002 Elsevier Science B.V. All rights reserved.