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Ishtiyak M, Watts SR, Thipe B, Womack F, Adams P, Bai X, Young DP, Bobev S, Baranets S. Advancing Heteroanionicity in Zintl Phases: Crystal Structures, Thermoelectric and Magnetic Properties of Two Quaternary Semiconducting Arsenide Oxides, Eu 8Zn 2As 6O and Eu 14Zn 5As 12O. Inorg Chem 2024. [PMID: 38904454 DOI: 10.1021/acs.inorgchem.4c01580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Two novel quaternary oxyarsenides, Eu8Zn2As6O and Eu14Zn5As12O, were synthesized through metal flux reactions, and their crystal structures were established by single-crystal X-ray diffraction methods. Eu8Zn2As6O crystallizes in the orthorhombic space group Pbca, featuring polyanionic ribbons composed of corner-shared triangular [ZnAs3] units, running along the [100] direction. The structure of Eu14Zn5As12O crystallizes in the monoclinic space group P2/m and its anionic substructure can be described as an infinite "ribbonlike" chain comprised of [ZnAs3] trigonal-planar units, although the structural complexity here is greater and also amplified by disorder on multiple crystallographic positions. In both structures, the O2- anion occupies an octahedral void with six neighboring Eu2+ cations. Formal electron counting, electronic structure calculations, and transport properties reveal the charge-balanced semiconducting nature of these heteroanionic Zintl phases. High-temperature thermoelectric transport properties measurements on Eu14Zn5As12O reveal relatively high resistivity (ρ500K = 8 Ω·cm) and Seebeck coefficient values (S500K = 220 μV K-1), along with a low concentration and mobility of holes as the dominant charge-carriers (n500K = 8.0 × 1017 cm-3, μ500K = 6.4 cm2/V s). Magnetic studies indicate the presence of divalent Eu2+ species in Eu14Zn5As12O and complex magnetic ordering, with two transitions observed at T1 = 21.6 K and T2 = 9 K.
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Affiliation(s)
- Mohd Ishtiyak
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Spencer R Watts
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Bhushan Thipe
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Frank Womack
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Philip Adams
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Xiaojian Bai
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - David P Young
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Svilen Bobev
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Sviatoslav Baranets
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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Synthesis and Crystal Structure of the Zintl Phases Na2CaCdSb2, Na2SrCdSb2 and Na2EuCdSb2. INORGANICS 2022. [DOI: 10.3390/inorganics10120265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
This work details the synthesis and the crystal structures of the quaternary Zintl phases Na2CaCdSb2, Na2SrCdSb2 and Na2EuCdSb2. They are isostructural and their noncentrosymmetric structure is with the space group Pmc21 (Pearson code oP12). All structural work is carried out via single-crystal X-ray diffraction methods. The structure features [CdSb2]4– layers of corner-shared CdSb4 tetrahedra, which are stacked along the b-crystallographic axis and are separated by cations. The results from the structure refinements suggest that in addition to full cation ordering, which is typical for this structure, there also exists a possibility for an accommodation of a small degree of cation disorder.
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