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Electronic conduction in La-based perovskite-type oxides

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ABSTRACT

A systematic study of La-based perovskite-type oxides from the viewpoint of their electronic conduction properties was performed. LaCo0.5Ni0.5O3±δ was found to be a promising candidate as a replacement for standard metals used in oxide electrodes and wiring that are operated at temperatures up to 1173 K in air because of its high electrical conductivity and stability at high temperatures. LaCo0.5Ni0.5O3±δ exhibits a high conductivity of 1.9 × 103 S cm−1 at room temperature (R.T.) because of a high carrier concentration n of 2.2 × 1022 cm−3 and a small effective mass m∗ of 0.10 me. Notably, LaCo0.5Ni0.5O3±δ exhibits this high electrical conductivity from R.T. to 1173 K, and little change in the oxygen content occurs under these conditions. LaCo0.5Ni0.5O3±δ is the most suitable for the fabrication of oxide electrodes and wiring, though La1−xSrxCoO3±δ and La1−xSrxMnO3±δ also exhibit high electronic conductivity at R.T., with maximum electrical conductivities of 4.4 × 103 S cm−1 for La0.5Sr0.5CoO3±δ and 1.5 × 103 S cm−1 for La0.6Sr0.4MnO3±δ because oxygen release occurs in La1−xSrxCoO3±δ as elevating temperature and the electrical conductivity of La0.6Sr0.4MnO3±δ slightly decreases at temperatures above 400 K.

No MeSH data available.


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The dependence of the mobility to (a) the Co−O bond angle and (b) the Co−O−Co bond angle. Reproduced from [6] by permission of The Royal Society of Chemistry.
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Figure 3: The dependence of the mobility to (a) the Co−O bond angle and (b) the Co−O−Co bond angle. Reproduced from [6] by permission of The Royal Society of Chemistry.

Mentions: Generally, the μ value increases when the Co–O–Co bond angle gets closer to 180° due to the increased overlap and strong interactions between the Co(3d)–O(2p) orbitals, leading to an increase in the relaxation time [27]. However, while the Co–O–Co bond angle did vary as a function of the average ionic radius at the A-site, the μ value did not. On the basis of these results, it can be concluded that no relation existed between μ and the Co–O–Co bond angle, as shown in figure 3(b). Consequently, the values for σ and μ cannot be improved by increasing the Co–O–Co bond angle to 180° in this system. In contrast, a relation between μ and the Co–O bond length was observed, as shown in figure 3(a). The μ value increased as the Co–O bond length decreased. Therefore, the variation in the behavior of μ as a function of the AE concentration when x ≥ 0.25 is presumed to be due to the difference in the Co–O bond lengths. This result coincides with a previous report concerning La1−xSrxCoO3 [33], although the behavior of the Co–O bond length as a function of the Sr concentration is not the same.


Electronic conduction in La-based perovskite-type oxides
The dependence of the mobility to (a) the Co−O bond angle and (b) the Co−O−Co bond angle. Reproduced from [6] by permission of The Royal Society of Chemistry.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036473&req=5

Figure 3: The dependence of the mobility to (a) the Co−O bond angle and (b) the Co−O−Co bond angle. Reproduced from [6] by permission of The Royal Society of Chemistry.
Mentions: Generally, the μ value increases when the Co–O–Co bond angle gets closer to 180° due to the increased overlap and strong interactions between the Co(3d)–O(2p) orbitals, leading to an increase in the relaxation time [27]. However, while the Co–O–Co bond angle did vary as a function of the average ionic radius at the A-site, the μ value did not. On the basis of these results, it can be concluded that no relation existed between μ and the Co–O–Co bond angle, as shown in figure 3(b). Consequently, the values for σ and μ cannot be improved by increasing the Co–O–Co bond angle to 180° in this system. In contrast, a relation between μ and the Co–O bond length was observed, as shown in figure 3(a). The μ value increased as the Co–O bond length decreased. Therefore, the variation in the behavior of μ as a function of the AE concentration when x ≥ 0.25 is presumed to be due to the difference in the Co–O bond lengths. This result coincides with a previous report concerning La1−xSrxCoO3 [33], although the behavior of the Co–O bond length as a function of the Sr concentration is not the same.

View Article: PubMed Central - PubMed

ABSTRACT

A systematic study of La-based perovskite-type oxides from the viewpoint of their electronic conduction properties was performed. LaCo0.5Ni0.5O3±δ was found to be a promising candidate as a replacement for standard metals used in oxide electrodes and wiring that are operated at temperatures up to 1173 K in air because of its high electrical conductivity and stability at high temperatures. LaCo0.5Ni0.5O3±δ exhibits a high conductivity of 1.9 × 103 S cm−1 at room temperature (R.T.) because of a high carrier concentration n of 2.2 × 1022 cm−3 and a small effective mass m∗ of 0.10 me. Notably, LaCo0.5Ni0.5O3±δ exhibits this high electrical conductivity from R.T. to 1173 K, and little change in the oxygen content occurs under these conditions. LaCo0.5Ni0.5O3±δ is the most suitable for the fabrication of oxide electrodes and wiring, though La1−xSrxCoO3±δ and La1−xSrxMnO3±δ also exhibit high electronic conductivity at R.T., with maximum electrical conductivities of 4.4 × 103 S cm−1 for La0.5Sr0.5CoO3±δ and 1.5 × 103 S cm−1 for La0.6Sr0.4MnO3±δ because oxygen release occurs in La1−xSrxCoO3±δ as elevating temperature and the electrical conductivity of La0.6Sr0.4MnO3±δ slightly decreases at temperatures above 400 K.

No MeSH data available.


Related in: MedlinePlus