Thermal expansion behavior and high-temperature electrical conductivity of A2−A ′Cu1−Co O4± (A = La, Pr; A′ = Pr, Sr) oxides with the K2NiF4-type structure
2015; Elsevier BV; Volume: 639; Linguagem: Inglês
10.1016/j.jallcom.2015.03.081
ISSN1873-4669
AutoresГ. Н. Мазо, С. М. Казаков, Л. М. Колчина, Anatolii V. Morozov, S.Ya. Istomin, Н. В. Лысков, А.А. Гиппиус, Evgeny V. Antipov,
Tópico(s)Advancements in Solid Oxide Fuel Cells
ResumoThree different compositional series of Pr-containing cuprates with the K2NiF4-type structure have been prepared by annealing at 1273 K, 48–90 h in air: with Cu on B-site only in formal oxidation state +2 (La2−xPrxCuO4, x = 0.1; 0.2; 0.4) (i), with partial replacement of Cu2+ by small (La2−xPrxCu1−yCoyO4±δ, 0.1 ⩽ x ⩽ 0.5; y = 0.05; 0.1) (ii) and large (Pr2−xSrxCu1−xCoxO4±δ, x = 0.5; 0.75) (iii) amount of cobalt. Partial replacement of Cu by Co, as in La2−xPrxCu1−yCoyO4±δ, leads to an increase of thermal expansion coefficients (TECs) in comparison with La2CuO4. Unusual high anisotropy of TEC along the a-(TEC(a)) and c-axes (TEC(c)) of the tetragonal unit cell is observed for Pr2−xSrxCu1−xCoxO4±δ, x = 0.5 and 0.75. TEC(c)/TEC(a) ratio increases with increasing amount of cobalt from 3.29 (x = 0.5) to 3.61 (x = 0.75). High-temperature electrical conductivity measurements at 298–1173 K in air reveal semiconductor-like behavior for all studied compositions with electrical conductivity values at 1173 K in air vary from 1.8 S/cm for La1.9Pr0.1Cu0.9Co0.1O4±δ to 5 S/cm for La1.6Pr0.4CuO4±δ and to 25 S/cm for Pr2−xSrxCu1−xCoxO4±δ, x = 0.5, 0.75.
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