Deconvoluting the Magnetic Structure of the Commensurately Modulated Quinary Zintl Phase Eu_11–xSr_xZn₄Sn₂As₁₂

Abstract

The structure, magnetic properties, and 151 Eu and 119 Sn Mossbauer spectra of the solid-solution Eu 11−x Sr x Zn 4 Sn 2 As 12 are presented. A new commensurately modulated structure is described for Eu 11 Zn 4 Sn 2 As 12 (R3m space group, average structure) that closely resembles the original structural description in the monoclinic C2/c space group with layers of Eu, puckered hexagonal Zn 2 As 3 sheets, and Zn 2 As 6 ethane-like isolated pillars. The solid-solution Eu 11−x Sr x Zn 4 Sn 2 As 12 (0 < x < 10) is found to crystallize in the commensurately modulated R3 space group, related to the parent phase but lacking the mirror symmetry. Eu 11 Zn 4 Sn 2 As 12 orders with a saturation plateau at 1 T for 7 of the 11 Eu 2+ cations ferromagnetically coupled (5 K) and shows colossal magnetoresistance at 15 K. The magnetic properties of Eu 11 Zn 4 Sn 2 As 12 are investigated at higher fields, and the ferromagnetic saturation of all 11 Eu 2+ cations occurs at ∼8 T. The temperature-dependent magnetic properties of the solid solution were investigated, and a nontrivial structure−magnetization correlation is revealed. The temperature-dependent 151 Eu and 119 Sn Mossbauer spectra confirm that the europium atoms in the structure are all Eu 2+ and that the tin is consistent with an oxidation state of less than four in the intermetallic region. The spectral areas of both Eu(II) and Sn increase at the magnetic transition, indicating a magnetoelastic effect upon magnetic ordering.

Experiment and Theory in Concert To Unravel the Remarkable Electronic Properties of Na-Doped Eu11Zn4Sn2As12: A Layered Zintl Phase

“…13−18 Eu 11 Zn 4 Sn 2 As 12 is an example of a layered Zintl phase with complex, directional bonding (Figure 1), a commensurately modulated structure with crystallographic disorder that has the potential for a wide variety of uses. 19,20 The crystal structure of Eu 11 Zn 4 Sn 2 As 12 is shown in Figure 1. It is composed of layers of Eu cations, [Zn 2 As 3 ] 5− defect honeycomb sheets, and pillars of ethane-like [Sn 2 As 6 ] 12− units with interspersed Eu atoms.…”

“…Using Eu binary compounds as synthetic precursors could unlock a multitude of compounds with novel properties, as Eu-based compounds are known to exhibit ferromagnetism, superconductivity, Kondo behavior, zero thermal expansion, high thermoelectric efficiency, and more, but an exploration of their properties has been limited by synthetic challenges. 10,14,15,19,20,31 Here, we present the synthesis of phase pure Eu 11 Zn 4 Sn 2 As 12 and dope the compound with Na to control carrier concentration. We measure thermoelectric properties and employ density functional theory (DFT) calculations to probe the low-dimensional electronic structure of Na-doped Eu 11 Zn 4 Sn 2 As 12 .…”

“…However, Zintl phases with layered structures are a vast and underexplored class of materials with directional bonding and great structural variety, making them excellent candidates for the quest to uncover low-dimensional electronic structures in bulk semiconductors. ,,, The combination of ionic and covalent bonding in Zintl compounds gives rise to diverse bonding motifs that can be tuned to adjust the electronic structures, providing more opportunities to engineer low-dimensional transport. Several layered Zintl phases, including Yb 2– x Eu x CdSb 2 , Eu 2 ZnSb 2 , and YbZn 2 Sb 2 , have already been shown to be promising thermoelectric materials and may find other applications (e.g., in catalysis) if their electronic structures can be better understood. − Eu 11 Zn 4 Sn 2 As 12 is an example of a layered Zintl phase with complex, directional bonding (Figure ), a commensurately modulated structure with crystallographic disorder that has the potential for a wide variety of uses. , …”

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides

“…Lowering of the reaction temperature to stabilize complex metastable or stable compounds is a common goal for solid state synthesis, [2][3][4][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] such as formation of metastable forms of RE oxychlorides via low-temperature pyrohydrolysis of (NH4)3REC16. 49 The mixing of the rare-earth and transition metals in the silicide precursors is somewhat akin to eutectic fluxes used in the Latturner group to make metal-rich intermetallics, [29][30][31][32][33][34] as well as flux syntheses of complex intermetallics performed by other groups.…”

“…49 The mixing of the rare-earth and transition metals in the silicide precursors is somewhat akin to eutectic fluxes used in the Latturner group to make metal-rich intermetallics, [29][30][31][32][33][34] as well as flux syntheses of complex intermetallics performed by other groups. [2][3][4][35][36][37][38][39][40][41][42][43][44][45][46][47][48] In-situ powder X-ray diffraction study was used to elucidate the mechanism of formation of such quaternaries. Detailed structural characterization by single crystal X-ray diffraction and 29 Si and 45 Sc solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies are reported.…”