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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 of La1−xSrxCoO3±δ. (a) Lattice angle and lattice length of the rhombohedral unit cell and the (b) Co–O–Co bond angle and Co–O bond length of the CoO6 octahedron. Reproduced from [7] by permission of The Royal Society of Chemistry.
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Figure 4: Lattice parameters of La1−xSrxCoO3±δ. (a) Lattice angle and lattice length of the rhombohedral unit cell and the (b) Co–O–Co bond angle and Co–O bond length of the CoO6 octahedron. Reproduced from [7] by permission of The Royal Society of Chemistry.

Mentions: The lattice parameters for La1−xSrxCoO3±δ optimized via Rietveld refinement [31] are shown in figure 4. The space group R-3c was used for the convergence in this refinement, although both R-3c and I2/a have been proposed for this system [28–30, 43]. The lattice angle (α) and the Co–O–Co bond angle approached 60° and 180°, respectively, with increasing Sr concentration for 0 ≤ x < 2/3; both then became saturated at x ≥ 2/3, indicating that the unit cell for La1−xSrxCoO3±δ changed from rhombohedral to cubic at x =2/3. This result suggests that the electrostatic attractive force between Co and O intensified as the Co–O–Co bond angle approached 180°. In this range, lattice length (a) also increased with the increasing Sr concentration, although the Co–O bond length decreased for x < 2/3.


Electronic conduction in La-based perovskite-type oxides
Lattice parameters of La1−xSrxCoO3±δ. (a) Lattice angle and lattice length of the rhombohedral unit cell and the (b) Co–O–Co bond angle and Co–O bond length of the CoO6 octahedron. Reproduced from [7] by permission of The Royal Society of Chemistry.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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Figure 4: Lattice parameters of La1−xSrxCoO3±δ. (a) Lattice angle and lattice length of the rhombohedral unit cell and the (b) Co–O–Co bond angle and Co–O bond length of the CoO6 octahedron. Reproduced from [7] by permission of The Royal Society of Chemistry.
Mentions: The lattice parameters for La1−xSrxCoO3±δ optimized via Rietveld refinement [31] are shown in figure 4. The space group R-3c was used for the convergence in this refinement, although both R-3c and I2/a have been proposed for this system [28–30, 43]. The lattice angle (α) and the Co–O–Co bond angle approached 60° and 180°, respectively, with increasing Sr concentration for 0 ≤ x < 2/3; both then became saturated at x ≥ 2/3, indicating that the unit cell for La1−xSrxCoO3±δ changed from rhombohedral to cubic at x =2/3. This result suggests that the electrostatic attractive force between Co and O intensified as the Co–O–Co bond angle approached 180°. In this range, lattice length (a) also increased with the increasing Sr concentration, although the Co–O bond length decreased for x < 2/3.

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.