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This study investigates the influence of dopant content and firing conditions on electrical properties and positive temperature coefficient of resistance (PTCR) effect of Ba${}_{1.005}$(Ti${}_{1-x}$Nb${}_x)$O₃ (BTN) ceramics sintered at different temperatures from 1070${}^{\circ }$C to 1220${}^{\circ }$C for 2 h in a reducing atmosphere and reoxidized within the temperature range of 600–750${}^{\circ }$C for 0.5–8 h. The results indicate that the room-temperature (RT) resistance of the laminated BTN specimens initially decreased and then increased as a function of the dopant concentration. Moreover, the resistance jump exhibited a contrasting tendency. Furthermore, the RT resistance of the BTN samples rapidly decreased at first and then gradually decreased with increasing sintering temperature. Meanwhile, the resistance jump of the samples increased first and then decreased. In addition, the influence of reoxidation times on the PTCR characteristics of ceramics was investigated.

This study investigates the influence of sintering conditions on electrical properties and positive temperature coefficient of resistance (PTCR) of ${\mathrm{\text{Ba}}}_{1.005}({\mathrm{\text{Ti}}}_{1-x}{\mathrm{\text{Nb}}}_x){\mathrm{\text{O}}}_3$ (BTNO) ceramics, fired at $1190^{\circ }$C for different times from 1 to 6 h in a reducing atmosphere and reoxidised within the temperature range of $600$–$900^{\circ }$C for 1 h. The results showed that the room-temperature (RT) resistance and the resistance jump of the multilayer BTNO ceramics decreased with an increase in the firing time. Furthermore, the RT resistance of the BTNO samples gradually increased at first and then rapidly increased with increasing reoxidation temperature. In addition, the influence of sintering times on the microstructure of ceramics was also investigated.

In this work, we investigate the influences of Ba/Ti ratio and sintering conditions on the characteristics of positive temperature coefficient of resistance (PTCR) and electrical properties of Ba${}_m$(Ti${}_{1-x}$Nb${}_x$)O₃ (BTN) ceramics. The ceramics were fired at 1190${}^{\circ }$C for 0.5–6.0 h in a reducing atmosphere and then reoxidized at 600–650${}^{\circ }$C for 0–8 h. The Ba/Ti ratio $(m)$ affected the electrical properties and PTCR effect of the BTN specimens. The room-temperature (RT) resistance of the BTN samples initially decreased $(0.994<m<1.006)$ and then increased $(1.006<m<1.018)$ as the Ba/Ti ratio increased. Moreover, BTN ceramics exhibit a pronounced PTCR effect, with a resistance jump greater by 3.0 orders of magnitude and a low 0.1 $\mathrm{\Omega }$ RT resistance at a low reoxidation temperature of 600${}^{\circ }$C after sintering under a reducing atmosphere. Furthermore, the average sample grain size increased along with the Ba/Ti ratio. In addition, the influence of the sintering time and the reoxidation time on the electrical properties and the PTCR effect were also investigated.