Layered cobalt oxide epitaxial films exhibiting thermoelectric <i>ZT</i> = 0.11 at room temperature

Takashima, Yugo; Zhang, Yuqiao; Feng, Bin; Ikuhara, Yuichi; Cho, Hai Jun; Ohta, Hiromichi

doi:10.1039/d0ta07565e

Cited by 26 publications

(43 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bearing in mind the above properties, better results of TE measurements were confirmed in the CAC samples. Moreover, S of undoped samples (111 µV/K for NCO-CAC and 100 µV/K for NCO-MASSR at T HOT = 830 K, ∆T = 473 K) was comparable with already reported values [21,[23][24][25].…”

Section: Resultssupporting

confidence: 89%

“…The figure of merit was calculated based on the obtained values for the electrical resistivity, the Seebeck coefficient and the thermal conductivity and its temperature dependence are presented in Figure 7. Taking into account both synthesis methods, the highest ZT was obtained for the sample NCO5-CAC (0.061 at ∆T = 473 K), mainly due to high S and low ρ, which is in accordance with ZT = 0.07, obtained for Na 0.75 CoO 2 epitaxial film [25]. This value was more than three times larger than ZT for the undoped CAC sample and 1.7 times larger than the highest value obtained for the MASSR sample (ZT(NCO3-MASSR) = 0.036 at ∆T = 473 K).…”

Section: Resultssupporting

confidence: 81%

See 1 more Smart Citation

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

et al. 2022

View full text Add to dashboard Cite

Polycrystalline samples of NaCo2−xCuxO4 (x = 0, 0.01, 0.03, 0.05) were obtained from powder precursors synthesized by a mechanochemically assisted solid-state reaction method (MASSR) and a citric acid complex method (CAC). Ceramic samples were prepared by pressing into disc-shaped pellets and subsequently sintering at 880 °C in an argon atmosphere. Effects of low concentrations of Cu doping and the above-mentioned synthesis procedures on the thermoelectric and mechanical properties were observed. The electrical resistivity (ρ), the thermal conductivity (κ) and the Seebeck coefficient (S) were measured simultaneously in the temperature gradient (ΔT) between the hot and cold side of the sample, and the figure of merit (ZT) was subsequently calculated. The ZT of the CAC samples was higher compared with the MASSR samples. The highest ZT value of 0.061 at ΔT = 473 K was obtained for the sample with 5 mol% of Cu prepared by the CAC method. The CAC samples showed better mechanical properties compared to the MASSR samples due to the higher hardness of the CAC samples which is a consequence of homogeneous microstructure and higher density obtained during sintering of these samples. The results confirmed that, besides the concentration of Cu, the synthesis procedure considerably affected the thermoelectric and mechanical properties of NaCo2O4 (NCO) ceramics.

show abstract

Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 81%

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

et al. 2022

View full text Add to dashboard Cite

show abstract

“…3,4 Ba 1/3 CoO 2 displays the highest thermoelectric conversion performance index at room temperature. 5 On the basis of the promising functions for practical applications, the layered cobalt oxides remain the primary subject of functional magnetoelectronic materials to date.…”

Section: ■ Introductionmentioning

confidence: 99%

High-Pressure Synthesis and Magnetic States of Magnetoplumbite Cobaltates CaCo₁₂O₁₉ and BaCo₁₂O₁₉

2021

View full text Add to dashboard Cite

Novel cobalt oxides, CaCo12O19 and BaCo12O19, have been synthesized under high-pressure and high-temperature conditions of 7 GPa and 1373 K, respectively. Rietveld refinement using synchrotron X-ray diffraction data indicates that the CaCo12O19 and BaCo12O19 crystallize in a magnetoplumbite structure with a hexagonal space group of P63/mmc (No. 194) as well as SrCo12O19. The magnetic study demonstrates that itinerant and localized 3d electrons coexist in all ACo12O19 (A = Ca, Sr, Ba) and the magnetic ground state transforms from antiferromagnetic (A = Ca) to ferrimagnetic (A = Sr) to antiferromagnetic (A = Ba), which is in stark contrast to the systematic change in the magnetoplumbite-related cobalt oxides of ACo6O11 from antiferromagnet (A = Ca) to ferrimagnet (A = Sr) to ferromagnet (A = Ba). The nonmonotonic magnetic evolution with isoelectronic A-site substitution in ACo12O19 is probably attributed to changes in the interactions between two magnetic sublattices of localized 3d electrons at trigonal-bipyramidal and tetrahedral sites for ACo12O19. This finding proposes the complex magnetic properties in the layered cobalt oxides with multiple magnetic sublattices in the coexistence system of itinerant and localized electrons.

show abstract

“…This could be related with the effects of the composite interfaces on the electric and thermal conductivity. It is worth mentioning that, at room temperature, the thermoelectric activity of the composites outperformed the previously reported layered cobalt oxide epitaxial films having the highest figure-of-merit (i.e., ZT = 0.11) [30].…”

Section: Thermoelectric Properties Of Multiphase Compositesmentioning

confidence: 61%

Composites between Perovskite and Layered Co-Based Oxides for Modification of the Thermoelectric Efficiency

et al. 2021

View full text Add to dashboard Cite

The common approach to modify the thermoelectric activity of oxides is based on the concept of selective metal substitution. Herein, we demonstrate an alternative approach based on the formation of multiphase composites, at which the individual components have distinctions in the electric and thermal conductivities. The proof-of-concept includes the formation of multiphase composites between well-defined thermoelectric Co-based oxides: Ni, Fe co-substituted perovskite, LaCo0.8Ni0.1Fe0.1O3 (LCO), and misfit layered Ca3Co4O9. The interfacial chemical and electrical properties of composites are probed with the means of SEM, PEEM/XAS, and XPS tools, as well as the magnetic susceptibility measurements. The thermoelectric power of the multiphase composites is evaluated by the dimensionless figure of merit, ZT, calculated from the independently measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (λ). It has been demonstrated that the magnitude’s electric and thermal conductivities depend more significantly on the composite interfaces than the Seebeck coefficient values. As a result, the highest thermoelectric activity is observed at the composite richer on the perovskite (i.e., ZT = 0.34 at 298 K).

show abstract

Layered cobalt oxide epitaxial films exhibiting thermoelectric ZT = 0.11 at room temperature

Abstract: Among many thermoelectric materials, oxide-based materials draw significant interest due to their environmental compatibility. In particular, layered cobaltite, Na0.75CoO2, shows a large thermoelectric power factor parallel to the layers. However,...

Cited by 26 publications

References 29 publications

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

High-Pressure Synthesis and Magnetic States of Magnetoplumbite Cobaltates CaCo₁₂O₁₉ and BaCo₁₂O₁₉

Composites between Perovskite and Layered Co-Based Oxides for Modification of the Thermoelectric Efficiency

Contact Info

Product

Resources

About

Layered cobalt oxide epitaxial films exhibiting thermoelectric ZT = 0.11 at room temperature

Abstract: Among many thermoelectric materials, oxide-based materials draw significant interest due to their environmental compatibility. In particular, layered cobaltite, Na0.75CoO2, shows a large thermoelectric power factor parallel to the layers. However,...

Cited by 26 publications

References 29 publications

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4

High-Pressure Synthesis and Magnetic States of Magnetoplumbite Cobaltates CaCo12O19 and BaCo12O19

Composites between Perovskite and Layered Co-Based Oxides for Modification of the Thermoelectric Efficiency

Contact Info

Product

Resources

About

High-Pressure Synthesis and Magnetic States of Magnetoplumbite Cobaltates CaCo₁₂O₁₉ and BaCo₁₂O₁₉