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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.


Lattice parameters for LaCo1−xNixO3±δ based on a rhombohedral unit cell. (a) Lattice constants of the a-axis and α angle, (b) B−O−B bond angle and B−O bond length and (c) bond-valence-sum for B-site ions. Reprinted with permission from [8]. Copyright © 2012 American Chemical Society.
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Figure 12: Lattice parameters for LaCo1−xNixO3±δ based on a rhombohedral unit cell. (a) Lattice constants of the a-axis and α angle, (b) B−O−B bond angle and B−O bond length and (c) bond-valence-sum for B-site ions. Reprinted with permission from [8]. Copyright © 2012 American Chemical Society.

Mentions: The crystal parameters were refined via Rietveld analysis [31] using the XRD patterns for LaCo1−xNixO3±δ (0 ≤ x ≤ 0.5)-sintered bodies and are shown in figure 12. The space group R-3c based on a rhombohedral lattice [83, 30] was used in this refinement. Both the a-axis and α angle varied monotonically with the Ni content, whereas the B−O bond length and the B−O−B bond angle were discontinuous and exhibited anomalies between 0.20 < x < 0.30. The B−O bond length increased with increasing x when 0 ≤ x ≤ 0.20, then abruptly decreased when 0.20 < x < 0.30 and finally increased again when 0.30 ≤ x ≤ 0.50. On the other hand, the B−O−B bond angle sharply increased from 164° to 166° as the Ni concentration increased from 0.20 to 0.30. However, the B−O−B bond angle was expected to decrease with the increasing Ni concentration because the tolerance factor for LaCo1−xNixO3±δ decreased with the increasing x. Thus, the increase in the B−O−B bond angle for 0.20 < x < 0.30 cannot be understood by considering the tolerance factor.


Electronic conduction in La-based perovskite-type oxides
Lattice parameters for LaCo1−xNixO3±δ based on a rhombohedral unit cell. (a) Lattice constants of the a-axis and α angle, (b) B−O−B bond angle and B−O bond length and (c) bond-valence-sum for B-site ions. Reprinted with permission from [8]. Copyright © 2012 American Chemical Society.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 12: Lattice parameters for LaCo1−xNixO3±δ based on a rhombohedral unit cell. (a) Lattice constants of the a-axis and α angle, (b) B−O−B bond angle and B−O bond length and (c) bond-valence-sum for B-site ions. Reprinted with permission from [8]. Copyright © 2012 American Chemical Society.
Mentions: The crystal parameters were refined via Rietveld analysis [31] using the XRD patterns for LaCo1−xNixO3±δ (0 ≤ x ≤ 0.5)-sintered bodies and are shown in figure 12. The space group R-3c based on a rhombohedral lattice [83, 30] was used in this refinement. Both the a-axis and α angle varied monotonically with the Ni content, whereas the B−O bond length and the B−O−B bond angle were discontinuous and exhibited anomalies between 0.20 < x < 0.30. The B−O bond length increased with increasing x when 0 ≤ x ≤ 0.20, then abruptly decreased when 0.20 < x < 0.30 and finally increased again when 0.30 ≤ x ≤ 0.50. On the other hand, the B−O−B bond angle sharply increased from 164° to 166° as the Ni concentration increased from 0.20 to 0.30. However, the B−O−B bond angle was expected to decrease with the increasing Ni concentration because the tolerance factor for LaCo1−xNixO3±δ decreased with the increasing x. Thus, the increase in the B−O−B bond angle for 0.20 < x < 0.30 cannot be understood by considering the tolerance factor.

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&plusmn;&delta; 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&plusmn;&delta; exhibits a high conductivity of 1.9 &times; 103 S cm&minus;1 at room temperature (R.T.) because of a high carrier concentration n of 2.2 &times; 1022 cm&minus;3 and a small effective mass m&lowast; of 0.10 me. Notably, LaCo0.5Ni0.5O3&plusmn;&delta; 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&plusmn;&delta; is the most suitable for the fabrication of oxide electrodes and wiring, though La1&minus;xSrxCoO3&plusmn;&delta; and La1&minus;xSrxMnO3&plusmn;&delta; also exhibit high electronic conductivity at R.T., with maximum electrical conductivities of 4.4 &times; 103 S cm&minus;1 for La0.5Sr0.5CoO3&plusmn;&delta; and 1.5 &times; 103 S cm&minus;1 for La0.6Sr0.4MnO3&plusmn;&delta; because oxygen release occurs in La1&minus;xSrxCoO3&plusmn;&delta; as elevating temperature and the electrical conductivity of La0.6Sr0.4MnO3&plusmn;&delta; slightly decreases at temperatures above 400 K.

No MeSH data available.