Thermoelectric phase diagram of the SrTiO3-LaTiO3 solid-solution system through a metal to Mott insulator transition

Zhang, Yuqiao; Sugo, Kenyu; Cho, Hai Jun; Ohta, Hiromichi

doi:10.1063/1.5100993

Cited by 13 publications

(22 citation statements)

References 51 publications

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“…In this study, even though there is an overestimation of κ ele , charge carriers (electrons) should play an important role in the different heat transfers of SLTO and STNO, since κ displays a consistent behavior with electron transport properties (summarized in Figure S3 of Supplementary). 25,26 Different from traditional solid solution systems, like Si x Ge 1−x or Al x Ga 1−x N, SLTO, and STNO show no sharp decrease in κ from alloying effect at low substitution level, suggesting a negligible effects from dopant defects on heat transfer. 46,47 In order to understand the different changing patterns of κ in SLTO and STNO, particularly the difference for n > 4 × 10 21 cm −3 , we refer to the lattice distortion, which can influence both κ ele and κ lat .…”

Section: Resultsmentioning

confidence: 92%

“…46,47 In order to understand the different changing patterns of κ in SLTO and STNO, particularly the difference for n > 4 × 10 21 cm −3 , we refer to the lattice distortion, which can influence both κ ele and κ lat . The lattice parameters in both out-of-plane and in-plane directions were extracted from the X-ray reciprocal space mappings (RSMs, Figures S5 and S6 in Supplementary) 25,26 around 103 diffraction spot of LaAlO 3 (q x /2π = 2.64 nm −1 , q z /2π = 7.92 nm −1 ) (Figure 5a). 103 diffraction spots of SrTiO 3 , SrNbO 3 , and LaTiO 3 are seen.…”

Section: Resultsmentioning

confidence: 99%

“…For LaTiO 3 , the internal parameters were optimized within the experimental cell volume. 25 For Sr 0.5 La 0.5 TiO 3 , the lattice parameters and atomic positions were fully relaxed with 8 × 8 × 6 Monkhorst-Pack of k-point grid, cutoff energy of 500 eV, and the force criterion of 10 −5 eV Å −1 . For phonon calculations, we performed the phonon calculations as implemented in PHONOPY.…”

Section: Phonon Dispersion Calculationmentioning

confidence: 99%

“…[19][20][21][22][23][24] The carrier electron concentration of SrTiO 3 can be controlled by substituting La for Sr or Nb for Ti. We have studied epitaxial films of SrTiO 3 −LaTiO 3 25 or SrTiO 3 −SrNbO 3 26 solid solutions and found that the carrier concentration (n) linearly increased with La or Nb concentration whereas the absolute value of S decreased. One can expect that the κ of the solid solution increases with increasing La or Nb concentration due to the increase in the electron contribution to the κ (=κ ele ) in addition to the lattice contribution to the κ (=κ lat ).…”

Section: Introductionmentioning

confidence: 99%

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Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

et al. 2021

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Electron-doped SrTiO 3 has been attracting attention as oxide thermoelectric materials, which can convert wasted heat into electricity. The power factor of the electrondoped SrTiO 3 , including SrTiO 3 -LaTiO 3 and SrTiO 3 -SrNbO 3 solid solutions, has been clarified. However, their thermal conductivity (κ) has not been clearly identified thus far. Only a high κ (>12 W m −1 K −1 ) has been assumed from the electron contribution based on Wiedemann-Franz law. Here, we show that the κ of the electrondoped SrTiO 3 is lower than the assumed κ, and its highest ZT exceeded 0.1 at room temperature. The κ slightly decreased with the carrier concentration (n) when n is below 4 × 10 21 cm −3 . In the case of SrTiO 3 -SrNbO 3 solid solutions, an upturn in κ was observed when n exceeds 4 × 10 21 cm −3 due to the contribution of conduction electron to the κ. On the other hand, κ decreased in the case of SrTiO 3 -LaTiO 3 solid solutions probably due to the lattice distortion, which scatters both electrons and phonons. The highest ZT was 0.11 around n = 1 × 10 21 cm −3 . These findings would be useful for the future design of electron-doped SrTiO 3 -based thermoelectric materials.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Phonon Dispersion Calculationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

et al. 2021

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“…The ultimate study of finding these transport properties is to investigate the possibility of promising thermoelectric materials by knowing the Figure of merit (transport coefficient) as shown in Fig.13. The higher the value of ZT confirms that the better the potential materials for thermoelectric application for recycling the wastage of heat energy [62,63].…”

Section: Transport Properties Of Srtio 3 and Latiomentioning

confidence: 79%

Electronic Structure and Transport Properties of Superlattices: La(1-X)SrxTiO3 (X =0, 0.20, 0.80, 1)

et al. 2020

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The conventional density functional theory (DFT) and dynamical mean field theory (DMFT) is used to study the structural, electronic and the Mott-Hubbard metal-insulator phase transition of the pristine and superstructures, La(1-x)SrxTiO3 (x = 0, 0.20, 0.80, 1). The electrical and thermal conductivities, Seebeck coefficient, Figure of merit are calculated using the BoltzTraP codes. The present study reveals that the direct band gap of 2.20 eV and indirect band gap ~2.0 eV at the Γ point in the Brillouin zone of SrTiO3 is upgraded to 3.423eV by using modified Beck-Johnson (mBJ) interaction potential. The metal-insulator transition (MIT) of LaTiO3 and the superlattice La(1-x)SrxTiO3 have been investigated by using conventional density functional theory (DFT) and dynamical mean field theory (DMFT). The Mott-Hubbard metal-insulator transitions for pristine LaTiO3 for a Coulombian parameter, U = 2.5 eV and the thermodynamic parameter β = 6 (eV)-1 are consistent with the experimental results. A typical set of these correlation parameters for MIT La0.20Sr0.80TiO3 and La0.80Sr0.20TiO3 systems are found to be U = 3.5 eV and β = 10(eV)-1 and U = 3.2 eV and β = 10 (eV)-1 respectively. The characteristic sharp quasi-particle peak for a sample of La0.80Sr0.20TiO3 superlattice systems is obtained correlation parameter U = 3.0 eV and β = 6(eV)-1. A thermoelectric phase transition is observed for Seebeck Coefficient at temperature 300 K at near chemical potential, μ = 1eV of SrTiO3. The corresponding figure of merit (ZT) with chemical potential (μ) appears to be unity at near μ = 1eV.

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Thermoelectric performance enhancement of environmentally‐friendly SrTiO₃ epitaxial films by hydrogen substitution

Kimura,

Ochiai,

et al. 2024

EcoEnergy

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Developing high‐efficiency and environmentally‐friendly thermoelectric materials has been a significant challenge. Conventional thermometric materials consist of heavy (toxic) elements to reduce thermal conductivity (κ), while we demonstrated light‐element hydride anion (H−) substitution in SrTiO3 can largely reduce κ and enhance thermometric efficiency (ZT) without heavy elements. In this paper, we succeeded in maximizing the ZT of SrTiO3−xHx by applying topochemical reaction directly to SrTiO3 epitaxial films with CaH2, which realized wide‐range control of carrier concentration (ne) from 1.5 × 1020 cm−3 to 4.1 × 1021 cm−3. The power factor (PF) showed a dome‐shaped behavior with respect to ne, and the maximum PF = 22.5 μW/(cmK2) was obtained at the optimal ne = 3.4 × 1020 cm−3. Carrier transport analyses clarified that the carrier mobility was limited by impurity scattering of H‐related impurities in the SrTiO3−xHx films, while the hydrogen substitution induced a much lower κ of 4.6 W/(mK) than other heavy‐element substituted Sr1−xLaxTiO3 and SrTi1−xNbxO3 films in the wide ne range, resulting in the higher ZT value of 0.14 in maximum at room temperature. In addition, the ZT increased to 0.17 at 373 K due to the large decrease in κ for a SrTiO3−xHx film with the hydrogen concentration of 1.2 × 1021 cm−3. Further study on H− substitution approach and modulation of the H state in transition metal oxides would lead to development of high ZT environmentally‐friendly thermoelectric materials.

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Thermoelectric phase diagram of the SrTiO3-LaTiO3 solid-solution system through a metal to Mott insulator transition

Cited by 13 publications

References 51 publications

Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

Electronic Structure and Transport Properties of Superlattices: La(1-X)SrxTiO3 (X =0, 0.20, 0.80, 1)

Thermoelectric performance enhancement of environmentally‐friendly SrTiO₃ epitaxial films by hydrogen substitution

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Thermoelectric phase diagram of the SrTiO3-LaTiO3 solid-solution system through a metal to Mott insulator transition

Cited by 13 publications

References 51 publications

Low thermal conductivity of SrTiO3−LaTiO3 and SrTiO3−SrNbO3 thermoelectric oxide solid solutions

Low thermal conductivity of SrTiO3−LaTiO3 and SrTiO3−SrNbO3 thermoelectric oxide solid solutions

Electronic Structure and Transport Properties of Superlattices: La(1-X)SrxTiO3 (X =0, 0.20, 0.80, 1)

Thermoelectric performance enhancement of environmentally‐friendly SrTiO3 epitaxial films by hydrogen substitution

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Product

Resources

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Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

Low thermal conductivity of SrTiO₃−LaTiO₃ and SrTiO₃−SrNbO₃ thermoelectric oxide solid solutions

Thermoelectric performance enhancement of environmentally‐friendly SrTiO₃ epitaxial films by hydrogen substitution