Abstract
CaCu3Ru4−xMnxO12 bulks with various substitution amounts x and sintering additive CuO (20 vol.%) were prepared, and the influence of x on the electrical conductivity in a wide temperature range (8–900 K) was investigated. Microstructural observations showed an enhancement of bulk densification upon Mn substitution. Although the resistivity increased with increasing x, the resistivity was as low as a few mΩcm even in the sample with x = 2.00, where half of Ru is substituted by Mn. This high conductivity despite the loss of Ru 4d conduction following the substitution is explained by the A-site (Cu2+) conduction in CaCu3Ru4−xMnxO12. The thermopower of CaCu3Ru4−xMnxO12 was found to be influenced by the substitution, and a sign inversion was observed in the substituted samples at low temperature. The partial substitution of Ru by Mn in CaCu3Ru4O12 enables the reduction of the materials cost while maintaining good electrical conductivity for applications as a conducting device component.
Highlights
Perovskites of the general formula AC3 B4 O12 represent a large family of materials and can be considered as a fourfold superstructure of the ABO3 perovskite in which a cation (A-site) andJahn-Teller ions (C-site; Cu2+, Mn3+ ) are long-range ordered in a double-cubic unit cell
We prepared CuO(20 vol.%)-CaCu3Ru4−xMnxO12 bulks with various substitution amounts x, and SEM observations and a calculation of the relative density showed an enhancement of the grain investigated the influence of x on the electrical resistivity
The CuO and CaCu3Ru4−xMnxO12 phases were detected by X-ray diffraction (XRD) in all samples, and a peak shift due to the substitution was confirmed
Summary
Perovskites of the general formula AC3 B4 O12 represent a large family of materials and can be considered as a fourfold superstructure of the ABO3 perovskite in which a cation (A-site) andJahn-Teller ions (C-site; Cu2+ , Mn3+ ) are long-range ordered in a double-cubic unit cell. Perovskites of the general formula AC3 B4 O12 represent a large family of materials and can be considered as a fourfold superstructure of the ABO3 perovskite in which a cation (A-site) and. A wide variety of cations can occupy the A-, B- and C-sites, and various partial substitutions are possible on each of these sites [1,2,3,4,5,6]. CaCu3 Ti4 O12 and CaMn3−x Cux Mn4 O12 show an anomalously high dielectric constant and a giant magneto-resistance, respectively [4,5,7,8,9]; LaCu3 Fe4 O12 is a negative thermal expansion material [10]; and CaCu3 Ru4 O12 exhibits high metallic electrical conductivity [11,12].
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