Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials

Isotta, Eleonora; Peng, Wanyue; Balodhi, Ashiwini; Zevalkink, Alexandra

doi:10.1002/anie.202213649

Cited by 28 publications

(25 citation statements)

References 217 publications

(435 reference statements)

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“…This is due to the magnetoelastic and elastic DMS behavior of Sn 0.7 Fe 0.3 O 2 and discussed in the Electronic Structure section. Softening occurred because C 44 was negative, suggesting that the materials were fragile. , Additionally, the shear modulus maintains a positive value in other dopant focuses, which limits its impact due to the characteristics of C 44 . A universal elastic anisotropy index [ A U = 5 GV / GR + BV / BR – 6] is to examine the development of micro cracks and the hardness of materials, as shown in Figure d.…”

Section: Resultsmentioning

confidence: 99%

“…This is due to the magnetoelastic and elastic DMS behavior of Sn 0.7 Fe 0.3 O 2 and normalS normaln 0.5 normalF normale 0.5 normalO 2 discussed in the Electronic Structure section. Softening occurred because C 44 was negative, suggesting that the materials were fragile. , Additionally, the shear modulus maintains a positive value in other dopant focuses, which limits its impact due to the characteristics of C 44 . A universal elastic anisotropy index [ A U = 5 GV / GR + BV / BR – 6] is to examine the development of micro cracks and the hardness of materials, as shown in Figure d.…”

Section: Resultsmentioning

confidence: 99%

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First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

Ramaraj,

SKS,

Zhang

et al. 2023

J. Phys. Chem. C

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We study the effects of Fe doping on the structural, electronic conductivity, elastic constants, and thermal conductivity of Sn 1−x Fe x O 2 (0 ≥ x ≤ 1) oxides by orbital hybridization as a consequence of charge remuneration of Fe 2+ /Fe 3+ and charge transfer using density functional theory calculations. We derive an effective spin-pseudospin Hamiltonian (H effective ) on the subspace of states with separately involved t 2g orbitals at each Fe site and visualize the combined atomic orbitals to form various molecular orbitals. Here, we determined that the mixed-valence electrons empowered by Fe 2+ −O 2− −Fe 3+ pairings in higher concentrations prevail through the double exchange-coupled pair. Specifically, we examined the oxygen positional parameters, average bond length, octahedral distortion, electronic structure, bulk modulus, shear modulus, Young's modulus, Poisson ratio, and thermal conductivity, which were significantly affected by the concentrations of x (0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1), leading to negative shear and Young's moduli, a large Gruneisen parameter, and a lower Debye temperature. We estimate an ultralow thermal conductivity for Sn 1−x Fe x O 2 of around 0.002−1.5 W m −1 K −1 at 300 K. We also found that fixations of the 0.5 and 0.3 dopants lead to ultralow thermal conductivity. The electronic structure of SnO 2 is 3.582 eV, and the maximum valence band is composed of the O-2p and Sn-5p states, while the conduction band minimum is between the O-2p and Sn-5s states. Fe doping modulates the bond strengths in Sn 1−x Fe x O 2 by introducing intermediate energy levels and increasing the degree of hybridization of the Fe-d, Sn-p, and O-p electron states. The reduced thermal conductivity at ambient temperature makes the material an effective candidate for use in thermal management materials and optoelectronic devices.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

Ramaraj,

SKS,

Zhang

et al. 2023

J. Phys. Chem. C

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“…The potential implications of the higher softening rate, as it relates to the anharmonicity of the material, are discussed in Isotta et al. 2022 [34] …”

Section: Resultsmentioning

confidence: 99%

Investigating the Role of Vacancies on the Thermoelectric Properties of EuCuSb‐Eu₂ZnSb₂ Alloys

et al. 2023

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AMX compounds with the ZrBeSi structure tolerate a vacancy concentration of up to 50 % on the M‐site in the planar MX‐layers. Here, we investigate the impact of vacancies on the thermal and electronic properties across the full EuCu1−xZn0.5xSb solid solution. The transition from a fully‐occupied honeycomb layer (EuCuSb) to one with a quarter of the atoms missing (EuZn0.5Sb) leads to non‐linear bond expansion in the honeycomb layer, increasing atomic displacement parameters on the M and Sb‐sites, and significant lattice softening. This, combined with a rapid increase in point defect scattering, causes the lattice thermal conductivity to decrease from 3 to 0.5 W mK−1 at 300 K. The effect of vacancies on the electronic properties is more nuanced; we see a small increase in effective mass, large increase in band gap, and decrease in carrier concentration. Ultimately, the maximum zT increases from 0.09 to 0.7 as we go from EuCuSb to EuZn0.5Sb.

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“…Umklapp processes are closely related to the anharmonic bonding features of a material, as quantified by the Grüneisen parameter. Although this is strictly mode dependent, thus rigorously obtained only via techniques like phonon DFT calculations or single-crystal neutron scattering experiments, it is possible to compute some thermodynamic estimates of the Grüneisen parameter via elasticity and thermal expansion data . Calculations and details of the employed methods are reported in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Influence of Ge Lone Pairs on the Elasticity and Thermal Conductivity of GeSe–AgBiSe₂ Alloys

Calderón-Cueva,

Isotta,

Rylko

et al. 2023

Chem. Mater.

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Chemical design is a compelling strategy to improve the performance of energy materials but requires a comprehensive understanding of how structure and chemistry affect materials properties. In this work, we investigate the structural, elastic, and thermal behavior of the (GeSe) 1−x −(AgBiSe 2 ) x system to shed light on the respective contributions of chemistry and crystal structure to thermal transport. In this system, progressive AgBiSe 2 alloying transforms the room-temperature structure from orthorhombic to rhombohedral to cubic rock-salt, with the latter being the thermodynamically stable phase across the entire compositional range at a high temperature. Within a given structure type, alloying progressively increases point-defect phonon scattering and decreases the speed of sound, thus reducing the lattice thermal conductivity. However, an anomalous increase in thermal conductivity is noticed upon the transition from the rhombohedral to the cubic phase, associated with a large step-like increase in the elastic moduli. Density functional theory calculations suggest this change in stiffness is due to the tendency of Ge to exhibit strongly expressed lone-pair orbitals. The lone pairs switch from fully oriented in the rhombohedral phase to randomly oriented in the cubic phase, leading to an overall bond stiffening. Supporting this argument, increased AgBiSe 2 content, and thus weakened lone-pair expression, leads to a less pronounced stiffening at the phase transition. These findings help improve our understanding of the intrinsic properties of this system and the design of rock-salt chalcogenides with tailored thermal properties.

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Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials

Cited by 28 publications

References 217 publications

First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

Investigating the Role of Vacancies on the Thermoelectric Properties of EuCuSb‐Eu₂ZnSb₂ Alloys

Influence of Ge Lone Pairs on the Elasticity and Thermal Conductivity of GeSe–AgBiSe₂ Alloys

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Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials

Cited by 28 publications

References 217 publications

First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

First-Principles Calculations to Investigate Coupling Fe Doping with Oxygen Vacancies in Stannic Oxide and Their Physical Properties

Investigating the Role of Vacancies on the Thermoelectric Properties of EuCuSb‐Eu2ZnSb2 Alloys

Influence of Ge Lone Pairs on the Elasticity and Thermal Conductivity of GeSe–AgBiSe2 Alloys

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Product

Resources

About

Investigating the Role of Vacancies on the Thermoelectric Properties of EuCuSb‐Eu₂ZnSb₂ Alloys

Influence of Ge Lone Pairs on the Elasticity and Thermal Conductivity of GeSe–AgBiSe₂ Alloys