Papers by Keyword: PTCR Effect

Abstract: We investigated the effect of the donor-doped content on the positive temperature coefficient of resistivity (PTCR) of (Ba_1-xSm_x)TiO₃ (BST) Based Ceramics that were sintered at 1300 °C for 30 min in a reducing atmosphere and re-oxidized at 850 °C for 1 h. The results indicated that the resistance jump first increased and then decreased with an increase of the donor-doped concentration. Moreover, the specimens achieved a low room temperature resistivity of 383.1 Ω·cm at a donor-doped content and exhibited a pronounced PTCR characteristics with a resistance jump of 3.1 orders of magnitude. Furthermore, the RT reisistivity of the samples reduced and increased with the increasing of the donor-dopant content in the range of 0.1−0.5 mol% Sm³⁺. In addition, the effect of the Sm³⁺-doped concentration on the grain size of the ceramics was investigated in our paper.

Abstract: The PTCR characteristics of (Ba_1-xSm_x)TiO₃ (BSMT) with different donor-doped concentration (x) sintered in a reducing atmosphere and reoxidized in air are investigated. The results reveal that the room temperature resistivity (ρ_RT) of the semiconducting BSMT ceramics first decreases and then increases with increasing of the x values, especially when x is 0.004, the semiconducting BSMT ceramics reoxidized at 850oC for 1 h after sintering at 1300 °C for 30 min in a reducing atmosphere achieve a lower room temperature resisitivity of 82.6 Ωcm. in addition, the doped 0.1 mol% Sm³⁺ BSMT samples fired at 1300 °C for 30 min in air exhibit remarkable PTCR effect with a resistance jumping ratio of 3.4 orders magnitude; moreover, a lower ρ_RT of the BSMT specimens sintered in a reducing atmosphere is obtained.

Abstract: Positive temperature coefficient of resistivity (PTCR) effect and electrical properties of (Ba_n-xSm_x)TiO₃ (BSMT ) samples with different Ba-site/Ti-site ratio (n) and various concentration of the donor-doped Sm³⁺ (x) sintered in a reducing atmosphere and reoxidized in air are investigated. The results show that the room temperature resistivity (ρ_RT) of the semiconducting BSMT ceramics first decreases and then increases with increasing of concentration of the donor-doped Sm³⁺, especially when x is 0.005 mol, the ρ_RT of the BSMT ceramics is the lowest. Moreover, the ρ_RT of the Ba-excess BSMT (n = 1.01) specimens reoxidized at 800 oC for 1 h after sintering at 1270 °C for 30 min in a reducing atmosphere is lower than the Ti-excess ones (n = 0.99), in addition, the ρ_RT of the BSMT specimens increases with an increase of both sintering temperature and reoxidized time.

Abstract: Electrical properties, positive temperature coefficient of resistivity (PTCR), and microstructures of (Ba_m-0.007Sm_0.007)TiO₃ (BST) with different Ba-site/Ti-site (A/B) ratio sintered in a reducing atmosphere and reoxidized in air are investigated. The results reveal that the room temperature resistivity of the semiconducting BST ceramics first decreases and then increases with increasing of A/B ratio (m), particularly when m is equal to 1.006, the semiconducting BST ceramics which have been sintered in a reducing atmosphere and reoxidized at 800°C exhibit significant PTCR effect with a resistance jumping ratio of 3 orders magnitude, and achieve a lower room temperature resisitivity of 80.8 Ω∙cm, in addition, the grain size distribution of the Ti-excess specimens is much better than that of the Ba-excess ones.