“…It could be explained by the sintered density, because low density restricted the path of charge carrier, which is agreement with the density analysis. The phenomenon can be found in the literature [28,44,45,46]. Furthermore, the aging performance of MCNS ceramics, at 125 ℃, has been assessed by resistance variation and results are shown in Fig.…”
Section: Electrical Characterization Xps and Impedance Analysismentioning
confidence: 80%
“…Therefore, the A3 ceramic exhibited distinct grain boundaries with some undesirable pores. It is worth emphasizing that an optimal amount of dopant is required to achieve the desired densification and avoid grain coarsening [27,28]. Fig.…”
Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2053.6 Ω·cm, 3654-3709 K, 0.3149-0.3197 eV and -4.111--4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. Furthermore, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with <1.3% of resistance shift after 100 thermal shock cycles.
“…It could be explained by the sintered density, because low density restricted the path of charge carrier, which is agreement with the density analysis. The phenomenon can be found in the literature [28,44,45,46]. Furthermore, the aging performance of MCNS ceramics, at 125 ℃, has been assessed by resistance variation and results are shown in Fig.…”
Section: Electrical Characterization Xps and Impedance Analysismentioning
confidence: 80%
“…Therefore, the A3 ceramic exhibited distinct grain boundaries with some undesirable pores. It is worth emphasizing that an optimal amount of dopant is required to achieve the desired densification and avoid grain coarsening [27,28]. Fig.…”
Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2053.6 Ω·cm, 3654-3709 K, 0.3149-0.3197 eV and -4.111--4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. Furthermore, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with <1.3% of resistance shift after 100 thermal shock cycles.
“…Therefore, the A3 ceramic exhibited distinct grain boundaries with some undesirable pores. It is worth emphasizing that an optimal amount of dopant is required to achieve the desired densification and avoid grain coarsening [27,28].…”
The Mn1.95−xCo0.21Ni0.84SrxO4 (MCNS) (0 ≼ x ≼ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure, and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the room resistivity ρ25, material constant B25/50, activation energy Ea, and temperature coefficient α values of MCNS ceramics are influenced by the Sr content and ranged in 1535.0–2053.6 Ω·cm, 3654–3709 K, 0.3149–0.3197 eV, and (−4.173%)–(−4.111%), respectively. The X-ray photoelectron spectroscopy (XPS) results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. The impedance data analysis also discusses the conduction mechanism of the MCNS ceramic, whereas grain resistance dominates the whole resistance of the samples. Furthermore, the aging coefficient (ΔR/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with < 1.3% of resistance shift after100 thermal shock cycles.
“…Therefore, the A3 ceramic exhibited distinct grain boundaries with some undesirable pores. It is worth emphasizing that an optimal amount of dopant is required to achieve the desired densification and avoid grain coarsening [27,28]. The relationship between (a) resistivity (ρ) and absolute temperature (T), and (b) ln (ρ) and reciprocal of absolute temperature (1000/T) of A0, A1, A2 and A3 ceramics.…”
Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) based negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relative density increase with the increase of Sr content. A small amount of Sr restrains the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2053.6 Ω·cm, 3654-3709 K, 0.3149-0.3197 eV and -4.111--4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. The conduction could arise from the hopping polaron between Mn3+/Mn4+ and Co2+/Co3+ in the octahedral sites. The impedance data analysis also discussed the conduction mechanism of the MCNS ceramic, while grain resistance dominates the whole resistance of the samples. Furthermore, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with <1.3% of resistance shift after 100 thermal shock cycles.
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