Fragment formalism in main-group solids: applications to aluminum boride (AlB2), calcium aluminum silicide (CaAl2Si2), barium-aluminum (BaAl4), and related materials

Burdett, Jeremy K.; Miller, Gordon J.

doi:10.1021/cm00007a004

Cited by 119 publications

(131 citation statements)

References 2 publications

(3 reference statements)

Supporting

Mentioning

122

Contrasting

Order By: Relevance

“…Burdett and Miller have described the bonding characteristics of CaAl 2 Si 2 -type compounds in great detail. 7 High zT has been reported for EuZn 2 Sb 2 (0.9 at 700 K 8 ) …”

Section: Introductionmentioning

confidence: 93%

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

et al. 2010

View full text Add to dashboard Cite

Visit the Dalton Transactions website for more cutting-edge inorganic and organometallic research www.rsc.org/dalton The AZn 2 Sb 2 (P3m1, A = Ca, Sr, Eu, Yb) class of Zintl compounds has shown high thermoelectric efficiency (zT~1) and is an appealing system for the development of Zintl structure-property relationships. High temperature transport measurements have previously been conducted for all known compositions except for SrZn 2 Sb 2 ; here we characterize polycrystalline SrZn 2 Sb 2 to 723 K and review the transport behavior of the other compounds in this class. Consistent with the known AZn 2 Sb 2 compounds, SrZn 2 Sb 2 is found to be a hole-doped semiconductor with a thermal band gap0 .27 eV. The Seebeck coefficients of the AZn 2 Sb 2 compounds are found to be described by similar effective mass (m*~0.6 m e ). Electronic structure calculations reveal similar m* is due to antimony p states at the valence band edge which are largely unaffected by the choice of A-site species. However, the choice of A-site element has a dramatic effect on the hole mobility, with the room temperature mobility of the rare earth-based compositions approximately double that found for Ca and Sr on the A site. This difference in mobility is examined in the context of electronic structure calculations.

show abstract

“…Burdett and Miller have described the bonding characteristics of CaAl 2 Si 2 -type compounds in great detail. 7 High zT has been reported for EuZn 2 Sb 2 (0.9 at 700 K 8 ) …”

Section: Introductionmentioning

confidence: 93%

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

et al. 2010

View full text Add to dashboard Cite

show abstract

“…Remarkable achievements have been reported with maximal ZT around or more than 1, e.g., β-Zn 4 Sb 3 (20,21), Yb 14 Mn 1−x Al x Sb 11 (22,23), and A y Mo 3 Sb 7-x Te x (24). In particular, Zintl phases AB 2 Sb 2 (A = Ca, Yb, Eu, Sr; B = Zn, Mn, Cd, Mg) (25)(26)(27)(28)(29) crystallizing in CaAl 2 Si 2 structure have been extensively studied with the highest ZT for YbZn 0.4 Cd 1.6 Sb 2 ∼ 1.2 at 700 K. The A sites of these materials have been shown to contain exclusively divalent ions, which are limited to alkalineearth-based and rare-earth-based elements like Eu and Yb, whereas B is a d 0 , d 5 , d 10 transition metal or a main-group element like Mg 2+ (30,31). Despite the extensive research on Zintl antimonides, analogous Bi-based Zintl materials have received little attention, even given the competitive TE performance of this system.…”

mentioning

confidence: 99%

Higher thermoelectric performance of Zintl phases (Eu _0.5 Yb _0.5 ) _1−x Ca _x Mg ₂ Bi ₂ by band engineering and strain fluctuation

Shuai

Geng

Lan

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

160

View full text Add to dashboard Cite

Complex Zintl phases, especially antimony (Sb)-based YbZn 0.4 Cd 1.6 Sb 2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg 2 Bi 2 with a record thermoelectric performance. Phase-pure EuMg 2 Bi 2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu 0.2 Yb 0.2 Ca 0.6 Mg 2 Bi 2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca, Yb,Eu)Mg 2 Bi 2 is better than the Sb-based Zintl phases. technology that converts heat into electricity, is currently used in subsea and spacecraft (1), and is foreseen to play an important role in the power industry and automobiles (2-5). Widespread applications are currently limited as a result of the low efficiency of TE materials (6). TE efficiency depends on the Carnot term as well as the TE figure-of-merit, ZT, defined as ZT = (S 2 σ/κ)T, where S, σ, κ, and T are the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature, respectively. S 2 σ is known as the power factor (PF) (7). Even though PF can be enhanced by electronic structure engineering, and κ can be reduced by an increase in phonon scattering, it is very difficult to independently increase PF and simultaneously decrease κ because they are oppositely related to carrier concentration and effective mass.As an alternative to evaluating the maximum ZT, a dimensionless material parameter B at particular temperature has proven to be useful (8-10).where m*, m 0 , μ, κ Lat , and T are the carrier effective mass, free electron mass, carrier mobility, lattice thermal conductivity, and absolute temperature, respectively. Therefore, heavy effective mass, high carrier mobility, and low lattice thermal conductivity are highly desirable for good TE performance. Practically, some strategies and concepts have been proposed to achieve this goal, e.g., band convergence and resonant states for heavier effective mass (11-13), band alignment and weak electron-phonon and alloy scattering to achieve high carrier mobility (14-16), and alloying or nanostructuring to enhance phonon scattering (17)(18)(19) (22,23), and A y Mo 3 Sb 7-x Te x (24). In particular, Zintl phases AB 2 Sb 2 (A = Ca, Yb, Eu, Sr; B = Zn, Mn, Cd, Mg) (25-29) crystalli...

show abstract

“…We therefore can search for new ferroelectric semiconductors by targeting intermetallic compounds in polar space groups and screening both reported and hypothetical compounds to find insulating representatives with a low barrier to uniform switching through a nonpolar reference phase, which provides an indication of the barrier to realistic switching. ABC compounds with polar space group P 6 3 mc in the LiGaGe structure type [14][15][16][17] are a promising target class. This structure, shown in Figure 1, is a hexagonal variant of the halfHeusler structure and can be described as a wurtzite structure "stuffed" with a third cation [18].…”

mentioning

confidence: 99%

HexagonalABCSemiconductors as Ferroelectrics

et al. 2012

View full text Add to dashboard Cite

We use a first-principles rational-design approach to identify a previously-unrecognized class of ferroelectric materials in the P 63mc LiGaGe structure type. We calculate structural parameters, polarization and ferroelectric well depths both for reported and as-yet hypothetical representatives of this class. Our results provide guidance for the experimental realization and further investigation of high-performance materials suitable for practical applications.A rapidly developing paradigm for the rational design of functional materials is based on the first-principles study of large families of known and as yet unreported compounds. First-principles calculations of structure and properties are used first to explore the microscopic origins and establish design principles for the functional properties of interest, and then to screen a large number of both equilibrium and metastable phases to identify promising candidate systems [1][2][3][4]. One recent study showed the semiconducting members of the ABC half-Heusler family to be piezoelectric, with a range of piezoelectric properties comparable to the much-studied ABO 3 perovskite oxides [4].A ferroelectric is a material with a polar phase produced by a structural transition from a nonpolar highsymmetry paraelectric state, with an electric polarization that can be switched between two or more symmetryrelated variants by application of an electric field [5]. The rational design of new ferroelectric materials is motivated both by fundamental scientific interest and by potential technological applications [6]. New materials can offer better performance, including reduction in switching time, in coercive field and in fatigue, operation at higher or lower temperatures, and the possibility of better integration with other materials based on structural or chemical compatibility. New ferroelectrics with lower band gaps for photoactive applications [7][8][9] are also of interest. Additional practical advantages could include decreased toxicity, for example Pb-free [10], and possible multifunctionality.Any polar structure (if insulating) could potentially support ferroelectricity if the barrier to switching is low enough [11][12][13]. We therefore can search for new ferroelectric semiconductors by targeting intermetallic compounds in polar space groups and screening both reported and hypothetical compounds to find insulating representatives with a low barrier to uniform switching through a nonpolar reference phase, which provides an indication of the barrier to realistic switching. ABC compounds with polar space group P 6 3 mc in the LiGaGe structure type [14][15][16][17] are a promising target class. This structure, shown in Figure 1, is a hexagonal variant of the halfHeusler structure and can be described as a wurtzite structure "stuffed" with a third cation [18]. The Inorganic Crystal Structural Database (ICSD) [19] includes 18 ABC compounds in this structure type that do not contain an f -block element. We can classify these combinations into the following groups: I-III...

show abstract

Fragment formalism in main-group solids: applications to aluminum boride (AlB2), calcium aluminum silicide (CaAl2Si2), barium-aluminum (BaAl4), and related materials

Cited by 119 publications

References 2 publications

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

Higher thermoelectric performance of Zintl phases (Eu _0.5 Yb _0.5 ) _1−x Ca _x Mg ₂ Bi ₂ by band engineering and strain fluctuation

HexagonalABCSemiconductors as Ferroelectrics

Contact Info

Product

Resources

About

Fragment formalism in main-group solids: applications to aluminum boride (AlB2), calcium aluminum silicide (CaAl2Si2), barium-aluminum (BaAl4), and related materials

Cited by 119 publications

References 2 publications

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

Electronic structure and transport in thermoelectric compounds AZn2Sb2 (A = Sr, Ca, Yb, Eu)

Higher thermoelectric performance of Zintl phases (Eu 0.5 Yb 0.5 ) 1−x Ca x Mg 2 Bi 2 by band engineering and strain fluctuation

HexagonalABCSemiconductors as Ferroelectrics

Contact Info

Product

Resources

About

Higher thermoelectric performance of Zintl phases (Eu _0.5 Yb _0.5 ) _1−x Ca _x Mg ₂ Bi ₂ by band engineering and strain fluctuation