On the origin of vibrational properties of calcium manganate based thermoelectric compounds

Andrei Baranovskiy; Ayelet Graff; Janina Klose; Joachim Mayer; Yaron Amouyal

doi:10.1016/j.nanoen.2018.02.054

On the origin of vibrational properties of calcium manganate based thermoelectric compounds

Andrei Baranovskiy, Ayelet Graff, Janina Klose, Joachim Mayer, Yaron Amouyal

Materials Science & Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

Vibrational properties of CaO(CaMnO₃)_m (m = 1, 2, 3, and ∞) thermoelectric (TE) oxides for high-temperature energy conversion applications are studied both experimentally and computationally. Density functional theory (DFT) calculations reveal strong scattering events involving dispersive acoustic phonons and non-dispersive optical modes in the frequency range of 3–5 THz. We demonstrate that the low frequency parts of the phonon spectra are strongly dominated by Ca-sublattice oscillations for all compounds of the CaO(CaMnO₃)_m (m = 1,2,3, ∞) series, which predicts enhanced phonon scattering upon Ca-sublattice site substitution defects. Accordingly, laser flash analysis (LFA) indicates considerable decrease of thermal conductivity (κ) due to La- substitution for Ca, whereas Nb- substitution for Mn-sites does not affect κ noticeably. It is found that thermal conductivity of CaO(CaMnO₃)_m compounds is governed by phonon scattering on CaO/CaMnO₃ boundaries for m = 1, 2, and 3 and by Umklapp processes for m = ∞. Thermal transport in this system is strongly dominated by acoustic phonon modes possessing much larger Grüneisen parameters (γ) compared to optical ones.

Original language	English
Pages (from-to)	451-462
Number of pages	12
Journal	Nano Energy
Volume	47
DOIs	https://doi.org/10.1016/j.nanoen.2018.02.054
State	Published - May 2018

Keywords

CaMnO perovskites
Grüneisen parameter
Lattice dynamics
Oxide thermoelectric materials
Phonon scattering
Thermal conductivity

ASJC Scopus subject areas

Renewable Energy, Sustainability and the Environment
General Materials Science
Electrical and Electronic Engineering

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10.1016/j.nanoen.2018.02.054

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title = "On the origin of vibrational properties of calcium manganate based thermoelectric compounds",

abstract = "Vibrational properties of CaO(CaMnO3)m (m = 1, 2, 3, and ∞) thermoelectric (TE) oxides for high-temperature energy conversion applications are studied both experimentally and computationally. Density functional theory (DFT) calculations reveal strong scattering events involving dispersive acoustic phonons and non-dispersive optical modes in the frequency range of 3–5 THz. We demonstrate that the low frequency parts of the phonon spectra are strongly dominated by Ca-sublattice oscillations for all compounds of the CaO(CaMnO3)m (m = 1,2,3, ∞) series, which predicts enhanced phonon scattering upon Ca-sublattice site substitution defects. Accordingly, laser flash analysis (LFA) indicates considerable decrease of thermal conductivity (κ) due to La- substitution for Ca, whereas Nb- substitution for Mn-sites does not affect κ noticeably. It is found that thermal conductivity of CaO(CaMnO3)m compounds is governed by phonon scattering on CaO/CaMnO3 boundaries for m = 1, 2, and 3 and by Umklapp processes for m = ∞. Thermal transport in this system is strongly dominated by acoustic phonon modes possessing much larger Gr{\"u}neisen parameters (γ) compared to optical ones.",

keywords = "CaMnO perovskites, Gr{\"u}neisen parameter, Lattice dynamics, Oxide thermoelectric materials, Phonon scattering, Thermal conductivity",

author = "Andrei Baranovskiy and Ayelet Graff and Janina Klose and Joachim Mayer and Yaron Amouyal",

note = "Publisher Copyright: {\textcopyright} 2018 Elsevier Ltd",

year = "2018",

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doi = "10.1016/j.nanoen.2018.02.054",

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T1 - On the origin of vibrational properties of calcium manganate based thermoelectric compounds

AU - Baranovskiy, Andrei

AU - Graff, Ayelet

AU - Klose, Janina

AU - Mayer, Joachim

AU - Amouyal, Yaron

PY - 2018/5

Y1 - 2018/5

N2 - Vibrational properties of CaO(CaMnO3)m (m = 1, 2, 3, and ∞) thermoelectric (TE) oxides for high-temperature energy conversion applications are studied both experimentally and computationally. Density functional theory (DFT) calculations reveal strong scattering events involving dispersive acoustic phonons and non-dispersive optical modes in the frequency range of 3–5 THz. We demonstrate that the low frequency parts of the phonon spectra are strongly dominated by Ca-sublattice oscillations for all compounds of the CaO(CaMnO3)m (m = 1,2,3, ∞) series, which predicts enhanced phonon scattering upon Ca-sublattice site substitution defects. Accordingly, laser flash analysis (LFA) indicates considerable decrease of thermal conductivity (κ) due to La- substitution for Ca, whereas Nb- substitution for Mn-sites does not affect κ noticeably. It is found that thermal conductivity of CaO(CaMnO3)m compounds is governed by phonon scattering on CaO/CaMnO3 boundaries for m = 1, 2, and 3 and by Umklapp processes for m = ∞. Thermal transport in this system is strongly dominated by acoustic phonon modes possessing much larger Grüneisen parameters (γ) compared to optical ones.

AB - Vibrational properties of CaO(CaMnO3)m (m = 1, 2, 3, and ∞) thermoelectric (TE) oxides for high-temperature energy conversion applications are studied both experimentally and computationally. Density functional theory (DFT) calculations reveal strong scattering events involving dispersive acoustic phonons and non-dispersive optical modes in the frequency range of 3–5 THz. We demonstrate that the low frequency parts of the phonon spectra are strongly dominated by Ca-sublattice oscillations for all compounds of the CaO(CaMnO3)m (m = 1,2,3, ∞) series, which predicts enhanced phonon scattering upon Ca-sublattice site substitution defects. Accordingly, laser flash analysis (LFA) indicates considerable decrease of thermal conductivity (κ) due to La- substitution for Ca, whereas Nb- substitution for Mn-sites does not affect κ noticeably. It is found that thermal conductivity of CaO(CaMnO3)m compounds is governed by phonon scattering on CaO/CaMnO3 boundaries for m = 1, 2, and 3 and by Umklapp processes for m = ∞. Thermal transport in this system is strongly dominated by acoustic phonon modes possessing much larger Grüneisen parameters (γ) compared to optical ones.

KW - CaMnO perovskites

KW - Grüneisen parameter

KW - Lattice dynamics

KW - Oxide thermoelectric materials

KW - Phonon scattering

KW - Thermal conductivity

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On the origin of vibrational properties of calcium manganate based thermoelectric compounds

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Keywords

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