Electronic structure, mechanical properties and thermal conductivity of Ln2Zr2O7 (Ln=La, Pr, Nd, Sm, Eu and Gd) pyrochlore

Feng, Jing; Xiao, Bing; Wan, Chao; Qu, Zhe; Huang, Zuocai; Chen, J.C.; Zhou, Rong; Pan, Wei

doi:10.1016/j.actamat.2010.11.041

Cited by 333 publications

(159 citation statements)

References 64 publications

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“…Different from the simple models invoked in those previous modeling studies of pyrochlore oxides [26][27][28]33], this approach allows direct considerations of phonon scattering processes and anharmonic relaxation times, 4 and is evidenced by a few studies to an accurate method to predict the thermal conductivity for a wide variety of solid-state materials [32,[34][35][36]. We focused on two sets of RE pyrochlores, Ln2Zr2O7 (Ln = La, Nd, Sm, Gd) and Gd2T2O7 (T = Zr, Hf, Sn, Pb).…”

Section: Introductionmentioning

confidence: 99%

“…Liu et al [26] and Feng et al [27,28] investigated the thermal conductivities of Ln2Zr2O7, Ln2Sn2O7 (Ln = La, Nd, Sm, Gd) and La2T2O7 (T = Ge, Ti, Sn Zr, Hf ) systems using density functional theory (DFT). In their studies, several physical properties, including elastic constants, lattice spacing and density, were computed from first-principles calculations, and subsequently combined with the simple formulas suggested by Clarke [29], Slack [30] and Cahill et al [31] to estimate the minimum thermal conductivity.…”

Section: Introductionmentioning

confidence: 99%

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The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

2015

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Rare-earth pyrochlores, commonly exhibiting anomalously low lattice thermal conductivities, are considered as promising topcoat materials for thermal barrier coatings. However the structural origin underlying their low thermal conductivities remain unclear. In the present study, we investigated the phonon properties of two groups of RE pyrochlores, Ln2Zr2O7 (Ln = La, Nd, Sm, Gd) and Gd2T2O7 (T = Zr, Hf, Sn, Pb) employing density functional theory and quasi harmonic approximation.Through the relaxation time approximation (RTA) with Debye model, the thermal conductivities of those RE pyrochlores were predicted, showing good agreement with experimental measurements. The low thermal conductivities of RE pyrochlores were shown to largely come from the interference between the low-lying optical branches and acoustic branches. The structural origin underlying the low-lying optical branches was then clarified and the competition between scattering processes in transverse and longitude acoustic branches was discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

2015

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“…Although the organic ions are important in photonic absorption and energy conversion, the electronic structure and interaction among organic and inorganic ions would have negligible effect for elastic properties. 36 The mechanical properties of CH 3 NH 3 BX 3 (B = Sn, Pb; X = Br, I) compounds are important in the analysis of the strain, stress, fracture mechanics, and deformation of solid absorber layers in application. We have investigated them by the stress-strain method based on the first-principles calculations.…”

mentioning

confidence: 99%

“…Moreover, the accurate electronic structures including band gap calculation have tiny effect in elastic properties calculation. 36 The Monkhorst-Pack type k point used in our calculations is 10 × 10 × 10, 10 × 8 × 10, and 8 × 8 × 10 for pseudocubic, orthorhombic, and tetragonal phases, respectively. The kinetic energy cutoff is set to 900 eV.…”

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confidence: 99%

Mechanical properties of hybrid organic-inorganic CH3NH3BX3 (B = Sn, Pb; X = Br, I) perovskites for solar cell absorbers

Feng¹

2014

Apl Materials

328

263

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The crystal structures, elastic and anisotropic properties of CH3NH3BX3 (B = Sn, Pb; X = Br, I) compounds as solar cell absorber layers are investigated by the first-principles calculations. The type and strength of chemical bond B-X are found to determine the elastic properties. B-X bonds and the organic cations are therefore crucial to the functionalities of such absorbers. The bulk, shear, Young's modulus ranges from 12 to 30 GPa, 3 to 12 GPa, and 15 to 37 GPa, respectively. Moreover, the interaction among organic and inorganic ions would have negligible effect for elastic properties. The B/G and Poisson's ratio show it would have a good ductile ability for extensive deformation as a flexible/stretchable layer on the polymer substrate. The main reason is attributed to the low shear modulus of such perovskites. The anisotropic indices AU, AB AG, A1, A2, and A3 show ABX3 perovskite have very strong anisotropy derived from the elastic constants, chemical bonds, and symmetry.

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“…Theoretical data, e.g., by [27] or [28], are also systematically displaced with respect to the curve shown in Fig. 4 and hence have also been excluded.…”

Section: Resultsmentioning

confidence: 99%

Compression behavior of Sm2Ti2O7-pyrochlore up to 50 GPa: single-crystal X-ray diffraction and density functional theory calculations

et al. 2014

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Single-crystal X-ray diffraction at pressures up to 50 GPa has been employed to study the compression behavior of Sm 2 Ti 2 O 7 -pyrochlore. In contrast to earlier reports, we observed no pressure-induced amorphization or pressure-induced anion disorder up to 50 GPa. The experimental study has been complemented by density functional theory-based calculations. A combination of the theoretical and experimental data yields a bulk modulus of %185 GPa, significantly higher than a value which had been reported earlier. In comparison to earlier work, the current study provides more reliable data due to the use of neon as a pressure medium, which provides a more hydrostatic pressure than the aluminum, which had been employed as a pressure medium in the earlier studies. An analysis of the compressibility of Al 2 B 2 O 7 pyrochlores shows an approximately linear dependence of the bulk modulus on the unit cell volume.

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Electronic structure, mechanical properties and thermal conductivity of Ln2Zr2O7 (Ln=La, Pr, Nd, Sm, Eu and Gd) pyrochlore

Cited by 333 publications

References 64 publications

The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

The role of low-lying optical phonons in lattice thermal conductance of rare-earth pyrochlores: A first-principle study

Mechanical properties of hybrid organic-inorganic CH3NH3BX3 (B = Sn, Pb; X = Br, I) perovskites for solar cell absorbers

Compression behavior of Sm2Ti2O7-pyrochlore up to 50 GPa: single-crystal X-ray diffraction and density functional theory calculations

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