Non-stoichiometric compositions arising from synergistic electronic and size effects. Synthesis, crystal chemistry and electronic properties of A14Cd1+xPn11compounds (0 ≤ x ≤ 0.3; A = Sr, Eu; Pn = As, Sb)

Makongo, Julien P. A.; Darone, Gregory M.; Xia, Sheng Qing; Bobev, Svilen

doi:10.1039/c5tc01605c

Cited by 21 publications

(33 citation statements)

References 78 publications

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Section: Introductionmentioning

confidence: 69%

“…Similar charge balancing issues exist for AE 14 MPn 11 ( M = Mg, Zn and Cd), where the d 10 metal atoms are clearly divalent , . Nature solves the electron deficiency in this instance by at least two different mechanisms – employing mixed‐valence of the cations, as demonstrated on the example of Yb 14 ZnSb 11 , or, as our recent studies on Sr 14 Cd 1+ x Sb 11 and Eu 14 Cd 1+ x Sb 11 suggest, these compounds have tendency to incorporate excess Cd/Zn at vacant interstitial sites, thereby augmenting the number of valence electrons. Neither approach, however, brings perfect charge balance (as in the AE 14 MPn 11 phases with M = Al, Ga, In, which are valence precise semiconductors following the Zintl–Klemm formalism), and these compounds are heavily degenerate p ‐type materials or even poor metals , …”

Section: Introductionmentioning

confidence: 69%

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On the Extended Series of Quaternary Zintl Phases Ca13REMnSb11 (RE = La–Nd, Sm, Gd–Dy)

et al. 2016

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Eight new compounds with a general formula Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd–Dy; x ≈ 1) were synthesized by the molten flux method and their structures were established via single‐crystal X‐ray diffraction. The overarching goal of this study was to investigate the effect of electron doping, via substitution of RE3+ at Ca2+ sites, on the crystal structure and physical properties of Ca14MnSb11, which is a candidate for thermoelectric applications. All studied phases are isostructural, and crystallize in the tetragonal body‐centered space group I41/acd (Ca14AlSb11 structure type, Pearson index tI208). The structure is made up of MnSb410– tetrahedra, randomly mixed Ca2+ and RE3+ cations, Sb3– anions, and linear Sb37– polyanions. Comprehensive structural work confirms high rare‐earth metal content with Ca2+/RE3+ randomly mixed on all four cation sites, with the caveat that the larger RE atoms (La–Nd) prefer to occupy the Ca2 site, while the smaller RE atoms (Sm, Gd, Tb, and Dy) preferably occupy the Ca1 site. Nearly phase‐pure polycrystalline samples have been synthesized using solid‐state reactions, and have been used for physical property measurements. The resistivities of the bulk Ca14–xRExMnSb11 (RE = La–Nd, Sm, Gd; x ≈ 1) samples reveal semiconducting behavior, consistent with the notion of electron doping in the parent p‐type Ca14MnSb11 material. Magnetic susceptibilities suggest complex magnetic ordering at temperatures below ca. 50 K, likely originating from coupling between two or more magnetic sub‐lattices.

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Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 69%

On the Extended Series of Quaternary Zintl Phases Ca13REMnSb11 (RE = La–Nd, Sm, Gd–Dy)

et al. 2016

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“…35 There may be interstitial Cd or Sb atoms in the structure, altering the unit cell parameters as has been indicated for Sr14CdSb11. 36 For the two rare earth elements, Eu and Yb, unit cell parameters also show similar dependence on the sizes of their ions. 34 Eu 2+…”

Section: A14mpn11 Structure Typementioning

confidence: 88%

“…The both Pn4 and Pn1 of the Pn3 7linear unit may have split sites in some analogs such as phosphides 37,39,[55][56][57] and arsenides. 36,40,41,43 This can manifest in large thermal ellipsoids in single crystal X-ray diffraction data refinement and typically various disorder models are employed to account for the electron density. In the P and As containing analogs, the central Pn atom in the There are four A sites and each one is surrounded by six Pn atoms in pseudo octahedral coordination as shown in Figure 5.…”

Section: A14mpn11 Structure Typementioning

confidence: 99%

“…compounds are paramagnetic and Eu14CdAs11 has magnetic transition at ~30 K as Cd is divalent, leaving a hole in the structure and increasing the carrier concentration. 36,46 When Eu and Mn are in the same compound, the magnetic interactions are stronger and the transition temperatures are higher. 39,46,89 Eu14MnPn11 has a ferromagnetic transition of 52 K for P, 74 K for As and 100 K for Sb.…”

Section: Magnetic and Electrical Propertiesmentioning

confidence: 99%

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The remarkable crystal chemistry of the Ca14AlSb11 structure type, magnetic and thermoelectric properties

Cerretti

Wille

et al. 2019

Journal of Solid State Chemistry

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Yb14MnSb11 is a member of a remarkable structural family of compounds that are classified according to the concept of Zintl. This structure type, of which the prototype is Ca14AlSb11, provides a flexible framework for tuning structure-property relationships and hence the physical and chemical properties of compounds. Compounds within this family show exceptional high temperature thermoelectric performance at temperatures above 300 K and unique magnetic and transport behavior at temperatures below 300 K. This review provides an overview of the structure variants, the magnetic properties, and the thermoelectric properties. Suggestions for directions of future research are provided. One active research area is to systematically explore more complex compositions such as Ca11Sb10, K4Pb9, Na8Si46, Ca14AlSb11 and KBa2InAs3. 3-7 The other direction is to replace the alkaline earth metals with divalent rare earth elements (Sm, Eu and Yb) along with the introduction of transition metals into structures, typically replacing the less electronegative metalloid in the anionic framework. 8-10 Combinations of these two directions led to compounds such as Yb14MnSb11, Pr4MnSb9, Eu10Mn6Sb13, Yb9Zn4+xBi9 and Cs13Nb2In6As10. 11-16 The complexity of compositions can be combined with a small flexibility in electron counting. For example, Yb14MnSb11 and Yb9Zn4+xBi9 do not strictly follow the Zintl-Klemm concept. Yb14MnSb11 has Mn 2+ instead of a group 13 element such as in Ca14AlSb11 and therefore is electron deficient, 17 and Yb9Zn4+xSb9 has interstitial Zn atoms which can be compositionally varied to achieve specific properties. 18 At the same time, the total number of valence electrons within an identical Zintl phase structure type with different elements may also vary slightly but the variance can be quite small and limited for many structure types that can be described by the Zintl concept. Therefore, with the introduction of transition elements, new electronic properties are possible, but complete transfer of electrons and clear counting of valence electrons remains a criterion for describing transition and rare earth metal containing Zintl phase compounds. Binary Zintl phase compounds which have compositions of simple ratios of elements usually adopt the structures of known oxides or halides, in which anions and cations are isolated in the structure with no covalent bonding. 2, 19 Both isolated anions, polyanions or clusters in Zintl phase compounds can provide complex compositions such as those represented by Ca11Sb10 and K4Pb9. 3, 4 Polyanions or clusters are formed to compensate for lack of enough electrons from the electropositive element to satisfy valence to form a simple one atom anion. Sb forms Sb-Sb single bonds in the Ca11Sb10 structure type resulting in Sb2 4and Sb4 2polyanions in the structure. 3 The Zintl electron counting provides the following charge balanced scenario: 11Ca 2+ + 4Sb 3-+ 2Sb2 4-+ Sb4 2-. Two types of clusters exist in K4Pb9 with the same formal oxidation state: a monocapped square antiprism and a tr...

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The Potential of Arsenic‐based Zintl Phases as Thermoelectric Materials: Structure & Thermoelectric Properties

Islam,

Kauzlarich

2023

Zeitschrift anorg allge chemie

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Zintl phase thermoelectric materials have generated tremendous interest due to possessing structural features conducive to high thermoelectric performances. On the other hand, both arsenic and arsenic‐based compounds have become attractive in electronics due to having interesting properties like narrow bandgap, tunable carrier concentration, and non‐centrosymmetric structures. The structure of arsenic compounds plays a telling role in determining their efficiency as thermoelectric materials. They also show the scope to be doped as both p‐ and n‐type conduction providing exciting new materials with applications as a full module. These attributes make them appealing as thermoelectric materials for further research. This short review is an overview of the different structures of arsenic‐based Zintl ternary materials that have potential to be excellent thermoelectric materials.

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Non-stoichiometric compositions arising from synergistic electronic and size effects. Synthesis, crystal chemistry and electronic properties of A₁₄Cd_1+xPn₁₁compounds (0 ≤ x ≤ 0.3; A = Sr, Eu; Pn = As, Sb)

Abstract: Synthesis and structural characterization of four compounds, isostructural, but not isoelectronic, with the thermoelectric material Yb14MnSb11.

Cited by 21 publications

References 78 publications

On the Extended Series of Quaternary Zintl Phases Ca13REMnSb11 (RE = La–Nd, Sm, Gd–Dy)

On the Extended Series of Quaternary Zintl Phases Ca13REMnSb11 (RE = La–Nd, Sm, Gd–Dy)

The remarkable crystal chemistry of the Ca14AlSb11 structure type, magnetic and thermoelectric properties

The Potential of Arsenic‐based Zintl Phases as Thermoelectric Materials: Structure & Thermoelectric Properties

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