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The first exploration of the impact of Yb 11 Sb 10 and Yb 10 MnSb 9 secondary phases in Yb 14 MnSb 11 , explaining years of confusing thermoelectric data.
Abstract Complex shapes are created from Yb 14 MnSb 11 , a high‐temperature thermoelectric Zintl phase, via a two‐step process: i) layer‐by‐layer 3D‐extrusion of ink containing partially‐reacted powders which are ball‐milled from a blend of Yb, MnSb, and Sb powders; ii) heat treatment to synthesize the ternary compound Yb 14 MnSb 11 and densify the extruded powders. A high phase purity for Yb 14 MnSb 11 (83–94%) is achieved in both cast and 3D‐extruded ink specimens via a solid‐state reaction between Yb, MnSb, and Yb 4 Sb 3 during reactive sintering. Pressure‐free sintering at temperatures of 1200–1400 °C densifies the powders to 82% relative density but can also induce the decomposition of the Yb 14 MnSb 11 phase due to Yb sublimation. A process window with optimized sintering temperature and time is identified, achieving both low porosity and high phase purity and reaching a maximum zT = 0.61 at 1000 °C, about half of the maximum zT value for bulk Yb 14 MnSb 11 made via conventional processes (pressure sintering of precursor powders). The present approach – direct ink writing of ball‐milled powders, combined with reactive sintering – is a scalable and affordable method to fabricate thermoelectric legs with intricate 3D shapes, for enhanced performances in high‐temperature thermoelectric applications.
The electrochemical oxidation of water to oxygen gas is the primary counter reaction to the formation of hydrogen gas via water splitting. In acidic media, the only well-established and active oxygen evolution catalysts are expensive noble metal oxides such as IrO x and RuO x , necessitating the development of practical oxygen evolution catalysts that are stable in acidic media. In this study, we prepared stoichiometric, phase-pure CoSb 2 O 6 and MnSb 2 O 6 electrodes using electrochemical synthesis and investigated their ability to oxidize water in 0.5 M H 2 SO 4 (pH 0.3). In addition, their stabilities during the oxygen evolution reaction (OER) were carefully examined by comparing their morphologies, crystallinities, compositions, and surface compositions before and after the OER. The chlorine evolution reaction on CoSb 2 O 6 and MnSb 2 O 6 in acidic media was also examined so that their performances can be compared with previously reported non-stoichiometric CoSb 2 O 6 and MnSb 2 O 6 electrodes. The electrochemical properties and stabilities of stoichiometric, phase-pure CoSb 2 O 6 and MnSb 2 O 6 reported in this study can provide useful insights into the development and understanding of acid-stable, non-noble metal oxide-based OER catalysts.
The creation and exploration of new materials under extreme pressure–temperature conditions has become increasingly reliant on laser-heated diamond anvil cell (LHDAC) techniques, which provide direct access to previously unexplored regions of multinary phase diagrams. Whereas numerous high-pressure phases have been identified in situ, systematic recovery and post-synthesis physical property characterization of these materials remain significant challenges. In this work, we describe the setup and implementation of an LHDAC-based synthesis and recovery workflow and demonstrate its application to metastable MnSb 2 and YbZn 2 phases. Synchrotron x-ray diffraction and spatial mapping confirm dominant formation of the targeted phases, whereas laboratory-based refinement quantifies phase fractions despite intrinsic microstrain and minor secondary phases. High-pressure transport measurements on recovered samples reveal pressure-tunable electronic instabilities in both systems. In MnSb 2 , pressure suppresses two high-temperature magnetic ordering anomalies, observed in transport, by ∼5 GPa and, for higher pressures, induces a new low-temperature feature that increases with further pressure increase. In hexagonal high-pressure YbZn 2 , an electronic reconstruction emerges at ∼11 GPa, characterized by semiconducting-like behavior from ∼30 to 300 K and a broad low-temperature coherence crossover near 30 K. Our results establish LHDAC synthesis not only as a structural discovery tool but also as an experimental platform for investigating correlated quantum states stabilized far from equilibrium thermodynamic conditions.
We report the magnetic imaging of ferromagnetic domains in the van der Waals single crystal MnSb 2 Te 4 from two different sources using cryogenic magnetic force microscopy. The magnetic field dependence of the domains reveals very weak pinning of domain walls in MnSb 2 Te 4 , resulting in a negligibly small magnetic hysteresis loop. Furthermore, the temperature dependence of the domain contrast reveals a mean field like behavior, in good agreement with that of bulk magnetization measurements.
Here, we study the ground state and spin excitations in Ba 3 MnSb 2 O 9 , an easy-plane S = 5/2 triangular lattice antiferromagnet. By combining single-crystal neutron scattering, electric spin resonance (ESR), and spin wave calculations, we determine the frustrated quasi-two-dimensional spin Hamiltonian parameters describing the material. While the material has a slight monoclinic structural distortion, which could allow for isosceles-triangular exchanges and biaxial anisotropy by symmetry, we observe no deviation from the behavior expected for spin waves in the in-plane $120$° state. Even the easy-plane anisotropy is so small that it can only be detected by ESR in our study. In conjunction with the quasi-two-dimensionality, our study establishes that Ba 3 MnSb 2 O 9 is a nearly ideal triangular lattice antiferromagnet with the quasiclassical spin S = 5/2, which suggests that it has the potential for an experimental study of Z- or Z 2 -vortex excitations.
Sr(MnSb)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Sr2+ is bonded to six equivalent Sb3- atoms to form SrSb6 octahedra that share corners with twelve equivalent MnSb4 tetrahedra, edges with six equivalent SrSb6 octahedra, and edges with six equivalent MnSb4 tetrahedra. All Sr–Sb bond lengths are 3.38 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form MnSb4 tetrahedra that share corners with six equivalent SrSb6 octahedra, corners with six equivalent MnSb4 tetrahedra, edges with three equivalent SrSb6 octahedra, and edges with three equivalent MnSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–51°. There are three shorter (2.77 Å) and one longer (2.78 Å) Mn–Sb bond lengths. Sb3- is bonded to three equivalent Sr2+ and four equivalent Mn2+ atoms to form a mixture of distorted corner and edge-sharing SbSr3Mn4 pentagonal bipyramids.
MnSb is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mn2+ is bonded to six equivalent Sb2- atoms to form a mixture of edge, corner, and face-sharing MnSb6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Mn–Sb bond lengths are 2.75 Å. Sb2- is bonded in a 6-coordinate geometry to six equivalent Mn2+ atoms.
MnSb is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Mn2+ is bonded in a body-centered cubic geometry to eight equivalent Sb2- atoms. All Mn–Sb bond lengths are 2.92 Å. Sb2- is bonded in a body-centered cubic geometry to eight equivalent Mn2+ atoms.
MnSb is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mn2+ is bonded to four equivalent Sb2- atoms to form corner-sharing MnSb4 tetrahedra. All Mn–Sb bond lengths are 2.68 Å. Sb2- is bonded to four equivalent Mn2+ atoms to form corner-sharing SbMn4 tetrahedra.
MnSb is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mn2+ is bonded to six equivalent Sb2- atoms to form a mixture of corner and edge-sharing MnSb6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mn–Sb bond lengths are 2.80 Å. Sb2- is bonded to six equivalent Mn2+ atoms to form a mixture of corner and edge-sharing SbMn6 octahedra. The corner-sharing octahedral tilt angles are 0°.
The tunability of Dirac semimetals with antiferromagnetic Mn layers is of great interest. The observed sign change of interlayer magnetic coupling between CaMnBi 2 and SrMnBi 2 suggests ionic substitution as a potential tuning mechanism. If so, novel behavior near the compensation point could be expected. Here, to explore this, we study a mixed-cation analog, Ca 0.6 Sr 0.4 MnSb 2 , where Bi is replaced by Sb. Conventional inelastic neutron scattering is impractical due to the small crystal size (m ≈ 0.28 g) available for compositional studies; however, we find that using a neutron diffractometer with a wide-angle area detector we can obtain a good quality spin-wave signal, which is shaped by energy-momentum conservation and retains spectroscopic information even without direct energy analysis. Spin-wave modeling reveals an interlayer coupling quantitatively similar to SrMnSb 2 , indicating it is not directly tuned by ionic size and that the sign change in Bi-based compounds likely arises from the observed change in lattice symmetry. Beyond this key insight, our results present an efficient method for parametric and compositional studies of spin dynamics in small crystals.
CaMn2Sb2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ca2+ is bonded to six equivalent Sb3- atoms to form CaSb6 octahedra that share corners with twelve equivalent MnSb4 tetrahedra, edges with six equivalent CaSb6 octahedra, and edges with six equivalent MnSb4 tetrahedra. All Ca–Sb bond lengths are 3.23 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form MnSb4 tetrahedra that share corners with six equivalent CaSb6 octahedra, corners with six equivalent MnSb4 tetrahedra, edges with three equivalent CaSb6 octahedra, and edges with three equivalent MnSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–53°. There are three shorter (2.75 Å) and one longer (2.77 Å) Mn–Sb bond lengths. Sb3- is bonded to three equivalent Ca2+ and four equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing SbCa3Mn4 pentagonal bipyramids.
YbMn2Sb2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Yb2+ is bonded to six equivalent Sb3- atoms to form YbSb6 octahedra that share corners with twelve equivalent MnSb4 tetrahedra, edges with six equivalent YbSb6 octahedra, and edges with six equivalent MnSb4 tetrahedra. All Yb–Sb bond lengths are 3.21 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form MnSb4 tetrahedra that share corners with six equivalent YbSb6 octahedra, corners with six equivalent MnSb4 tetrahedra, edges with three equivalent YbSb6 octahedra, and edges with three equivalent MnSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–53°. There are three shorter (2.74 Å) and one longer (2.77 Å) Mn–Sb bond lengths. Sb3- is bonded to three equivalent Yb2+ and four equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing SbYb3Mn4 pentagonal bipyramids.
BaMn2Sb2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba2+ is bonded in a body-centered cubic geometry to eight equivalent Sb3- atoms. All Ba–Sb bond lengths are 3.66 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form a mixture of edge and corner-sharing MnSb4 tetrahedra. All Mn–Sb bond lengths are 2.70 Å. Sb3- is bonded in a 4-coordinate geometry to four equivalent Ba2+ and four equivalent Mn2+ atoms.
EuMn2Sb2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Eu2+ is bonded to six equivalent Sb3- atoms to form EuSb6 octahedra that share corners with twelve equivalent MnSb4 tetrahedra, edges with six equivalent EuSb6 octahedra, and edges with six equivalent MnSb4 tetrahedra. All Eu–Sb bond lengths are 3.28 Å. Mn2+ is bonded to four equivalent Sb3- atoms to form MnSb4 tetrahedra that share corners with six equivalent EuSb6 octahedra, corners with six equivalent MnSb4 tetrahedra, edges with three equivalent EuSb6 octahedra, and edges with three equivalent MnSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–52°. There are three shorter (2.76 Å) and one longer (2.77 Å) Mn–Sb bond lengths. Sb3- is bonded to three equivalent Eu2+ and four equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing SbEu3Mn4 pentagonal bipyramids.
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