Nanostructured Nb-substituted CaMnO<sub>3</sub> n-type thermoelectric material prepared in a continuous process by ultrasonic spray combustion

Populoh, Sascha; Trottmann, Matthias; Aguire, Myriam H.; Weidenkaff, Anke

doi:10.1557/jmr.2011.140

Cited by 20 publications

(10 citation statements)

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“…Material family References Mn oxide [49][50][51][52][53][54][55][56][57][58][59][60] ZnO, SrTiO 3 33, [61][62][63][64][65][66][67][68][69][70][71][72] Co oxide 34,35,[73][74][75][76][77] other oxide 28,63,[78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96] Si-Ge …”

Section: Acknowledgementmentioning

confidence: 99%

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

et al. 2013

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In this review, we describe the creation of a large database of thermoelectric materials prepared by abstracting information from over 100 publications. The database has over 18 000 data points from multiple classes of compounds, whose relevant properties have been measured at several temperatures. Appropriate visualization of the data immediately allows certain insights to be gained with regard to the property space of plausible thermoelectric materials. Of particular note is that any candidate material needs to display an electrical resistivity value that is close to 1 mW cm at 300 K, i.e., samples should be significantly more conductive than the Mott minimum metallic conductivity. The Herfindahl-Hirschman index, a commonly accepted measure of market concentration, has been calculated from geological data (known elemental reserves) and geopolitical data (elemental production) for much of the periodic table. The visualization strategy employed here allows rapid sorting of thermoelectric compositions with respect to important issues of elemental scarcity and supply risk.

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Section: Acknowledgementmentioning

confidence: 99%

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

et al. 2013

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“…The CaMnO 3 and Ca 2 MnO 4 compounds of the CaO(CaMnO 3 ) m series have been thoroughly investigated in previous works owing to their electronic and thermal transport properties. Both compounds, denoted as the m = ∞ and 1 derivatives of this series, respectively, are characterized by the number of perovskite CaMnO 3 subunits alternating between rock‐salt CaO planes 11–22 . Interestingly, it was found that the transport properties of the Ca 3 Mn 2 O 7 ( m = 2) and Ca 4 Mn 3 O 10 ( m = 3) phases lay in between those of the end members ( m = ∞ and 1), possessing valuable TE virtues, as well 18,19,23,24 …”

Section: Introductionmentioning

confidence: 99%

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

et al. 2022

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We investigate phase stability, microstructure, and thermoelectric transport of polycrystalline bulk Ca3−xRxMn2O7 samples prepared by standard solid‐state reaction, where R = Y or La and 0 ≤ x ≤ 0.33. Ab‐initio calculations predict that Y‐doping at Ca‐sites should reduce the potential energy barrier for electron transport, as opposed to La‐doping. We find that Y‐doping prompts transformation from Ca3Mn2O7 to Ca2MnO4, whereas La‐doping is accompanied by no phase transformation. La‐doping significantly hinders grain growth, for example, the average grain size decreases from 4.44 ± 0.24 to 1.20 ± 0.03 μm for x = 0 (undoped) and x = 0.33 upon La‐doping, respectively. Electrical conductivity and Seebeck coefficients are measured for the temperature range of 300–1300 K, and analyzed in terms of the small polaron hopping model. We find that Y‐doping reduces the activation energy for conduction compared to La‐doping, for example, 43 and 63 meV, respectively. This suggests that Y reduces the energy barrier for polaron transport, in accordance with computational predictions. This trend is further supported by calculations of selected electronic, structural, and vibrational properties, highlighting the intriguing correlation between electronic transport governed by small polarons and elastic properties, thereby shedding light on charge transport and thermoelectric properties of such layered perovskites.

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“…Finding a suitable porous morphology with a better ratio of the electrical to thermal conductivities could result in increasing the ZT values. 22,23 Mesoporous samples have been prepared by different methods like Chimie douce synthesis 24 or citric acid-assisted soft chemistry synthesis. 25 In this work, a nanostructuring approach producing porous samples has been applied on EuTi 1Àx Nb x O 3Àd (x ¼ 0.00; 0.02).…”

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Electronic structure and thermoelectric properties of nanostructured EuTi1−xNbxO3−δ (x = 0.00; 0.02)

Sagarna

Shkabko

Populoh

et al. 2012

Applied Physics Letters

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The thermoelectric properties of polycrystalline nanostructured EuTiO 3Àd samples are improved by a substitution of 2% Nb for Ti. The figure of merit (ZT) was measured to reach ZT(EuTi 0.98 Nb 0.02 O 3Àd ) % 0.4 at T ¼ 1040 K while ZT(EuTiO 3Àd ) % 0.3 at the same temperature. X-ray photoelectron spectra reveal that the in-gap states at the Fermi level are more pronounced for the Nb-substituted samples, resulting in an improved power factor. The valence band peak below the Fermi level is sharply shaped, therefore fulfilling the condition for a large Seebeck coefficient. The specific porosity of the samples reduces the lattice thermal conductivity with a minor effect on the electron transport. V C 2012 American Institute of Physics.[http://dx.It is known from theoretical studies that correlation effects in oxides can enhance thermoelectric properties. 1,2 Predictions about the thermoelectric performance and the Seebeck coefficient of strongly correlated electron systems were presented by Rüegg et al. 3 Among the perovskite-type oxides, SrTiO 3 has shown a particularly high thermoelectric figure of merit ((ZT ¼ (S 2 T)/(jq), where S ¼ Seebeck coefficient, q ¼ electrical resistivity, j ¼ thermal conductivity, and T ¼ absolute temperature) in the high-temperature region. 4,5 In order to enhance ZT, q and j have to be minimized and S has to be maximized. The lattice thermal conductivity is often decreased by substituting heavy atoms into the crystal structure, which enhance the phonon scattering. 6 A recent approach to decrease the j of Ti containing perovskite systems (ATiO 3 ; where A ¼ rare earth or alkaline earth metal) have focused on substitutions of the A-site cation with heavier elements. A 20% substitution of Sr 2þ by Eu 2þ in SrTiO 3 was found to effectively reduce the mean free phonon path by 12% at room temperature. 7 Based on this observation and taking into account the similarities between SrTiO 3 and EuTiO 3 , 8,9 a l o w e rp h o n o nm e a nf r e ep a t hi se x p e c t e di nE u T i O 3 due to thehigheratomicmassofEuascomparedwithSr.EuTiO 3 has been widely studied because of its interesting magnetic properties: it is one of the few antiferromagnetic materials with a positive Curie-Weiss constant (h) 10 and reveals a strong coupling between magnetic ordering and soft phonon modes. 11 Electronic band structure calculations of EuTiO 3 by Ranjan et al. 12 have predicted a sharp peak in the density of states (DOS) below the Fermi level (E f ), which is beneficial to increase the S (/(@ ln f(E)/ @E) E¼Ef ). A broad band dispersion near E f would further enhance the electronic conductivity. 13 The electrical conductivity of EuTiO 3 has been studied at low temperatures, 14 and different methods have been applied for its synthesis. 15,16 Another approach to reduce the lattice thermal conductivity is based on nanostructuring. 17 When the grain size decreases and approaches a scale comparable to the mean free path, the phonons are scattered by the grain boundaries. Moreover, nanostructuring can enhance the Seebe...

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Nanostructured Nb-substituted CaMnO₃ n-type thermoelectric material prepared in a continuous process by ultrasonic spray combustion

Cited by 20 publications

References 11 publications

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Electronic structure and thermoelectric properties of nanostructured EuTi1−xNbxO3−δ (x = 0.00; 0.02)

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Nanostructured Nb-substituted CaMnO3 n-type thermoelectric material prepared in a continuous process by ultrasonic spray combustion

Cited by 20 publications

References 11 publications

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

Data-Driven Review of Thermoelectric Materials: Performance and Resource Considerations

Ca3Mn2O7‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport

Electronic structure and thermoelectric properties of nanostructured EuTi1−xNbxO3−δ (x = 0.00; 0.02)

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Nanostructured Nb-substituted CaMnO₃ n-type thermoelectric material prepared in a continuous process by ultrasonic spray combustion

Ca₃Mn₂O₇‐layered perovskites: Effects of La‐ and Y‐doping on phase stability, microstructure, and thermoelectric transport