Valence band study of thermoelectric Zintl-phase<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SrZn</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Sb</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>YbZn</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><

Flage−Larsen, Espen; Diplas, Spyros; Prytz, Øystein; Toberer, Eric S.; May, Andrew F.

doi:10.1103/physrevb.81.205204

Cited by 32 publications

(15 citation statements)

References 35 publications

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“…Strong correlations of the Eu 4f orbitals considered by applying the GGA + U approach with U eff = 7 eV (rotationally invariant formulation [22]). For consistency with the previous theoretical work on d 10 metal antimonides [23,24], we also introduced U eff = 2 eV for the Cd 4d states. Spin polarization was treated in a simple ferromagnetic model.…”

Section: Methodsmentioning

confidence: 98%

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

et al. 2018

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Investigation of the quaternary system, Ca–Eu–Cd–Sb, led to a discovery of the new solid solutions, Ca1−xEuxCd2Sb2, with the CaAl2Si2 structure type (x ≈ 0.3–0.9, hP5, Ptrue3¯m1, a = 4.6632(5)–4.6934(3) Å, c = 7.630(1)–7.7062(7) Å), Ca2−xEuxCdSb2 with the Yb2CdSb2 type (x ≈ 0.6, oS20, Cmc21, a = 4.646(2) Å, b = 17.733(7) Å, c = 7.283(3) Å), and Eu11−xCaxCd6Sb12 with the Sr11Cd6Sb12 type (x ≈ 1, mS58, C2/m, a = 32.407(4) Å, b = 4.7248(5) Å, c = 12.377(1) Å, β = 109.96(1)°). Systematic crystallographic studies of the Ca1−xEuxCd2Sb2 series indicated expansion of the unit cell upon an increase in the Eu content, in accordance with a larger ionic radius of Eu2+ vs. Ca2+. The Ca2−xEuxCdSb2 composition with x ≈ 0.6 adopts the non-centrosymmetric space group, Cmc21, although the parent ternary phase, Ca2CdSb2, crystallizes in the centrosymmetric space group, Pnma. Two non-equivalent Ca sites in the layered crystal structure of Ca2−xEuxCdSb2 get unevenly occupied by Eu, with a preference for the interlayer position, which offers a larger available volume. Similar size-driven preferred occupation is observed in the Eu11−xCaxCd6Sb12 solid solution with x ≈ 1.

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Section: Methodsmentioning

confidence: 98%

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

et al. 2018

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“…However, CaAl 2 Si 2 -type compounds have the potential to exhibit physical properties that are just as interesting as the more heavily investigated ThCr 2 Si 2 -type compounds. Within the ternary pnictide systems A-Zn-Pn, the antimonides AZn 2 Sb 2 (A ¼alkaline-earth metals such as Sr or divalent rare-earth metals such as Eu) have been recently identified as promising thermoelectric materials [2][3][4][5][6][7][8][9]. Furthermore, CaAl 2 Si 2 -type phases serve as an attractive platform to design other structures.…”

Section: Introductionmentioning

confidence: 99%

Ternary CaCu4P2-type pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb)

Stoyko

Khatun

Mullen

et al. 2012

Journal of Solid State Chemistry

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“…While nominally charge balanced and predicted to be narrow gap semiconductors, 8,19,20 these materials possess p-type conduction with carrier densities generally on the order of 10 19 -10 20 cm −3 , though semiconducting behavior was reported for CaCd 2 Sb 2 .…”

mentioning

confidence: 99%

Thermoelectric transport properties of CaMg2Bi2, EuMg2Bi
May
¹
,
McGuire
²
,
Singh
³

et al. 2012
Phys. Rev. B
Self Cite

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The thermoelectric transport properties of CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2 were characterized between 2 and 650 K. As synthesized, the polycrystalline samples are found to have lower p-type carrier concentrations than single-crystalline samples of the same empirical formula. These low carrier concentration samples possess the highest mobilities yet reported for materials with the CaAl2Si2 structure type, with a mobility of ∼740 cm 2 /V/s observed in EuMg2Bi2 at 50 K. Despite decreases in the Seebeck coefficient (α) and electrical resistivity (ρ) with increasing temperature, the power factor (α 2 /ρ) increases for all temperatures examined. This behavior suggests a strong asymmetry in the conduction of electrons and holes. The highest figure of merit (zT ) is observed in YbMg2Bi2, with zT approaching 0.4 at 600 K for two samples with carrier densities of approximately 2×1018 cm −3 and 8×10 18 cm −3 at room temperature. Refinements of neutron powder diffraction data yield similar behavior for the structures of CaMg2Bi2 and YbMg2Bi2, with smooth lattice expansion and relative expansion in c being ∼35% larger than relative expansion in a at 973 K. First principles calculations reveal an increasing band gap as Bi is replaced by Sb then As, and subsequent Boltzmann transport calculations predict an increase in α for a given n associated with an increased effective mass as the gap opens. The magnitude and temperature dependence of α suggests higher zT is likely to be achieved at larger carrier concentrations, roughly an order of magnitude higher than those in the current polycrystalline samples, which is also expected from the detailed calculations.

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Valence band study of thermoelectric Zintl-phaseSrZn2Sb2andYbZn2<

Cited by 32 publications

References 35 publications

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

Ternary CaCu4P2-type pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb)

Thermoelectric transport properties of CaMg2Bi2, EuMg2Bi
May
¹
,
McGuire
²
,
Singh
³

et al. 2012
Phys. Rev. B
Self Cite

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Valence band study of thermoelectric Zintl-phaseSrZn2Sb2andYbZn2<

Cited by 32 publications

References 35 publications

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

Ternary CaCu4P2-type pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb)

Thermoelectric transport properties of CaMg2Bi2, EuMg2BiMay1, McGuire2, Singh3 et al. 2012Phys. Rev. BSelf Cite

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Thermoelectric transport properties of CaMg2Bi2, EuMg2Bi
May
¹
,
McGuire
²
,
Singh
³

et al. 2012
Phys. Rev. B
Self Cite