Strongly Correlated Properties and Enhanced Thermoelectric Response in Ca3Co4−xMxO9 (M = Fe, Mn, and Cu)

Wang, Yang; Sui, Yu; Ren, Peng; Wang, Lan; Wang, Xianjie; Su, Wenhui; Fan, Hong Jin

doi:10.1021/cm902483a

Cited by 143 publications

(203 citation statements)

References 48 publications

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“…Now we stress that this is consistent with our resistivity results. In this system, the resistivity minimum around 70 K is associated with an onset of SDW gap formation [41,42]. Therefore, according to above scenario, the onset temperature should increase with increasing Rh content.…”

Section: Discussionmentioning

confidence: 84%

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Ikeda

Saito

Okazaki

2016

Journal of Applied Physics

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We have examined an isovalent Rh substitution effect on the transport properties of the thermoelectric oxide Ca 3 Co 4 O 9 using single-crystalline form. With increasing Rh content x, both the electrical resistivity and the Seebeck coefficient change systematically up to x = 0.6 for Ca 3 Co 4−x Rh x O 9 samples. In the Fermi-liquid regime where the resistivity behaves as ρ = ρ 0 + AT 2 around 120 K, the A value decreases with increasing Rh content, indicating that the correlation effect is weakened by Rh 4d electrons with extended orbitals. We find that, in contrast to such a weak correlation effect observed in the resistivity of Rh-substituted samples, the low-temperature Seebeck coefficient is increased with increasing Rh content, which is explained with a possible enhancement of a pseudogap associated with the short-range order of spin density wave. In high-temperature range above room temperature, we show that the resistivity is largely suppressed by Rh substitution while the Seebeck coefficient becomes almost temperature-independent, leading to a significant improvement of the power factor in Rh-substituted samples. This result is also discussed in terms of the differences in the orbital size and the associated spin state between Co 3d and Rh 4d electrons.

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Section: Discussionmentioning

confidence: 84%

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Ikeda

Saito

Okazaki

2016

Journal of Applied Physics

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“…Such performances are believed to be a result of Ca 3 Co 4 O 9?d crystallographic structure, consisting of two misfit layers: the CaO-CoOCaO rocksalt-type layer and the CdI 2 -type CoO 2 layer [5]. Ca 3 Co 4 O 9?d polycrystals, on the other hand, still exhibits lower performances, with ZT \ 0.3 [6][7][8][9][10]. This has to be improved before it can be implemented for any real applications.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of transition metals-doped Ca3Co3.8M0.2O9+δ (M = Co, Cr, Fe, Ni, Cu and Zn)

Pinitsoontorn

Lerssongkram

Keawprak

et al. 2011

J Mater Sci: Mater Electron

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The thermoelectric properties of the Ca 3 Co 4 O 9?d and the transition metals-doped Ca 3 Co 3.8 M 0.2 O 9?d (where M = Cr, Fe, Ni, Cu and Zn) ceramics were reported. Ca 3 Co 4 O 9?d single phase was checked by using X-ray diffraction analysis performed for the Ca 3 Co 3.8-M 0.2 O 9?d samples. The scanning electron micrographs showed some degrees of grains alignment in the compacted direction. The resistivity of the samples measured from 100 up to 700°C varies in magnitude for different transition metals substitution. The variation of resistivity was explained by a change of carrier concentration induced by the doped ions. The thermopower increased with increasing temperature but showed no obvious change for any transition metals doping. The thermal conductivities changed for the doped samples but were relatively independent of temperature. The ZT was calculated to be the highest for the Fe substitution for the whole measurement temperature with the maximum value of 0.12 at 700°C.

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“…To further examine the impurity effect, we compare two characteristic lengths, ξ 0 and ξ imp . Using the carrier concentration n ≃ 6 × 10 21 cm −3 [30] and the effective mass m * ≃ 13m 0 [31], ξ 0 is calculated as ξ 0 ≃ 4 nm. On the other hand, ξ imp is estimated as ξ imp ≃ 4 nm for x = 0.1 sample [32], comparable to ξ 0 , indicating that the impurities certainly affect the temperature dependence of the threshold field in this system.…”

Section: Resultsmentioning

confidence: 99%

Nonlinear transport associated with spin density wave dynamics in Ca3Co4O9

et al. 2017

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We have carried out the transient nonlinear transport measurements on the layered cobalt oxide Ca 3 Co 4 O 9 , in which a spin density wave (SDW) transition is proposed at T SDW ≃ 30 K. We find that, below T SDW , the electrical conductivity systematically varies with both the applied current and the time, indicating a close relationship between the observed nonlinear conduction and the SDW order in this material. The time dependence of the conductivity is well analyzed by considering the dynamics of SDW which involves a low-field deformation and a sliding motion above a threshold field. We also measure the transport properties of the isovalent Sr-substituted systems to examine an impurity effect on the nonlinear response, and discuss the obtained threshold fields in terms of thermal fluctuations of the SDW order parameter.

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Strongly Correlated Properties and Enhanced Thermoelectric Response in Ca₃Co_4−xM_xO₉ (M = Fe, Mn, and Cu)

Cited by 143 publications

References 48 publications

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Thermoelectric transport in the layered Ca3Co4–xRhxO9 single crystals

Thermoelectric properties of transition metals-doped Ca3Co3.8M0.2O9+δ (M = Co, Cr, Fe, Ni, Cu and Zn)

Nonlinear transport associated with spin density wave dynamics in Ca3Co4O9

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