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DOE OSTI2022

Superconducting properties of the spin Hall candidate Ta 3 Sb with eightfold degeneracy

We report the synthesis and characterization of phase pure Ta 3 Sb, a material predicted to be topological with eightfold degenerate fermionic states [Bradlyn et al., Science 353, aaf5037 (2016)] and to exhibit a large spin Hall effect [Derunova et al., Sci. Adv. 5, eaav8575 (2019)]. We observe superconductivity in Ta 3 Sb with T c ~0.67 K in both electrical resistivity ρ(T) and specific heat c(T) measurements. Field-dependent measurements yield the superconducting phase diagram with an upper critical field of H c2 (0) ~0.95 T, corresponding to a superconducting coherence length of ξ ≈ 18.6 nm. The gap ratio deduced from specific heat anomaly, 2Δ 0 /k B T c is 3.46, a value close to the Bardeen-Cooper-Schrieffer value of 3.53. From a detailed analysis of both the transport and thermodynamic data within the Ginsburg-Landau (GL) framework, a GL parameter of κ ≈ 90 is obtained, identifying Ta 3 Sb as an extreme type-II superconductor. The observation of superconductivity in an eightfold degenerate fermionic compound with topological surface states and predicted large spin Hall conductance positions Ta 3 Sb as an appealing platform to further explore exotic quantum states in multifold degenerate systems.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Large magnetoresistance and first-order phase transition in antiferromagnetic single-crystalline EuAg 4 Sb 2

Here, we present the results of a thorough investigation of the physical properties of EuAg 4 Sb 2 single crystals using magnetization, heat capacity, and electrical resistivity measurements. High-quality single crystals, which crystallize in a trigonal structure with space group 𝑅⁢$\bar{3}$𝑚, were grown using a conventional flux method. Temperature-dependent magnetization measurements along different crystallographic orientations confirm two antiferromagnetic phase transitions around 𝑇 𝑁⁢1 = 10.5K and 𝑇 𝑁⁢2 = 7.5K. Isothermal magnetization data exhibit several metamagnetic transitions below these transition temperatures. Antiferromagnetic phase transitions in EuAg 4 Sb 2 are further confirmed by two sharp peaks in the temperature-dependent heat capacity data at 𝑇 𝑁⁢1 and 𝑇 𝑁⁢2 , which shift to lower temperature in the presence of an external magnetic field. Our systematic heat capacity measurements utilizing a long-pulse and single-slope analysis technique allow us to detect a first-order phase transition in EuAg 4 Sb 2 at 7.5 K. The temperature-dependent electrical resistivity data also manifest two features associated with magnetic order. The magnetoresistance exhibits a broad hump due to a field-induced metamagnetic transition. Remarkably, the magnetoresistance keeps increasing without showing any tendency to saturate as the applied magnetic field increases, and it reaches ∼20 000% at 1.6 K and 60 T. At high magnetic fields, several magnetic quantum oscillations are observed, indicating a complex Fermi surface. A large negative magnetoresistance of about −55% is also observed near 𝑇 𝑁⁢1 . Moreover, the 𝐻−𝑇 phase diagram constructed using magnetization, heat capacity, and magnetotransport data indicates complex magnetic behavior in EuAg 4 Sb 2 .

36 MATERIALS SCIENCE↗

DOE OSTI2020

$β$-delayed-neutron studies of 135,136 Sb and 140 I performed with trapped ions

In this work, Beta-delayed-neutron $(βn)$ spectroscopy was performed using the Beta-decay Paul Trap and an array of radiation detectors. The $βn$ branching ratios and energy spectra for 135,136 Sb and 140 I were obtained by measuring the time of flight of recoil ions emerging from the trapped ion cloud. These nuclei are located at the edge of an isotopic region identified as having $βn$ branching ratios that impact the $r$-process abundance pattern around the A ≈ 130 peak. For 135,136 Sb and 140 I, $βn$ branching ratios of 14.6(13)%, 17.6(29)%, and 7.6(28)% were determined, respectively. The $βn$ energy spectra obtained for 135 Sb and 140 I are compared with results from direct neutron measurements, and the $βn$ energy spectrum for 136 Sb has been measured for the first time.

42 ENGINEERING↗

DOE OSTI2023

Antiferromagnetic Fe Te 2 1 T - phase formation at the Sb 2 Te 3 / Ni 80 Fe 20 interface

Bilayer topological insulator/ferromagnet (TI/FM) heterostructures are promising for spintronic applications due to their low switching energy and therefore power efficiency. Until recently, the reactivity of TI with FM films was overlooked in the spin orbit-torque literature, even though there are reports that it is energetically favorable for TIs to react with transition metals and form interfacial layers. Here, in this study we fabricated a TI/FM heterostructure comprised of molecular beam epitaxy grown Sb 2 Te 3 and DC sputtered Ni 80 Fe 20 . Broadband ferromagnetic resonance revealed spin-pumping evident by the significant enhancement in Gilbert damping, which is likely a signature of the topological surface states or the presence of large spin-orbit-coupling in the adjacent Sb 2 Te 3 . With low-temperature magnetometry, an exchange bias is observed which indicates an exchange interaction between an antiferromagnet (AFM) and an adjacent FM. Cross-section high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) characterization of the Sb 2 Te 3 - Ni 80 Fe 20 bilayer revealed a complex interface showing diffusion of Fe and Ni into the Sb 2 Te 3 film yielding the formation of a FeTe 2 1T-type structural phase. Furthermore, density functional theory calculations revealed that the FeTe 2 1T-phase has an AFM ground state. Due to experimental limitations in the electron energy loss spectroscopy measurements precise chemistry of the interfacial phase could not be determined, therefore it is possible that the FeTe 2 1T and/or an intermixed (Fe 1-x Ni x )Te 2 1T is the AFM interfacial phase contributing to exchange bias in the system. This work emphasizes the chemical complexity of TI/FM interfaces that host novel, metastable magnetic topological phases and require more in-depth studies of other similar interfaces.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2023

Structural transition and anisotropic magnetism in disordered Zintl phase Eu 7 Ga 6 Sb 8

Single crystals of the Zintl compound Eu 7 Ga 6 Sb 8 were synthesized using a Ga-Sb flux. We report the temperature (T) and magnetic field (H) dependence of the magnetic susceptibility (χ), magnetization (M), resistivity (ρ), specific heat (C), and thermal expansion (α). We also report high-resolution powder x-ray diffraction data that support a structural phase transition with accompanying signatures seen in C(T), ρ(T), and α(T). We find Eu 7 Ga 6 Sb 8 exhibits antiferromagnetic ordering at T N1 = 9.0 K from anomalies seen in χ(T), C(T), and α(T), as well as a potential reorientation of Eu 2+ spins at T N2 = 7.5 K and T N3 = 7.2 K. In conclusion, density functional theory calculations predict Eu 7 Ga 6 Sb 8 to be semiconducting; however, electrical resistivity measurements show bad-metal behavior that indicates the presence of disorder.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Solid-phase heteroepitaxy of oriented Sb 2 Se 3 on GaAs for birefringent thin films

Here, we investigate the amorphous-to-crystalline transformation of antimony selenide (Sb 2 Se 3 ) on UHV-prepared GaAs (001) substrates. In the bulk orthorhombic form, Sb 2 Se 3 is a layered quasi-1D semiconductor with highly anisotropic properties of interest for optical and electronic devices. We find that an amorphous layer deposited by molecular beam epitaxy annealed at or above 230 °C yields a textured-epitaxial structure among some randomly oriented domains. The textured-epitaxial Sb 2 Se 3 grains are oriented with the covalently bonded “1D axis” constrained in-plane to GaAs [110] and with multiple van der Waals (hk0) orientations out-of-plane. The same texture was achieved exclusively without randomly oriented grains using continuous-wave laser radiation, highlighting the use of thermal and optical methods to yield anisotropic crystalline Sb 2 Se 3 films directly from the amorphous phase. Polarized reflectance and polarized microscopy confirm the unique state of in-plane birefringence in the crystallized thin film. Overall, we show that solid-phase heteroepitaxy provides additional pathways to the integration of low-symmetry chalcogenide semiconductors for demanding applications where the inherent anisotropy needs to be preserved.

Xiao, Kelly [Stanford Univ., CA (United States)] (↗

DOE OSTI2020

Materials Data on Sb(MoS)2 by Materials Project

Sb(MoS)2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded in a 6-coordinate geometry to two equivalent Sb3- and four S2- atoms. Both Mo–Sb bond lengths are 2.91 Å. There are a spread of Mo–S bond distances ranging from 2.37–2.61 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded in a 3-coordinate geometry to three equivalent Sb3- and three equivalent S2- atoms. There are one shorter (2.88 Å) and two longer (2.92 Å) Mo–Sb bond lengths. There are two shorter (2.37 Å) and one longer (2.39 Å) Mo–S bond lengths. Sb3- is bonded in a 5-coordinate geometry to five Mo+3.50+ atoms. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three equivalent Mo+3.50+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to four Mo+3.50+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sb(OF3)2 by Materials Project

SbF6O2 crystallizes in the cubic Ia-3 space group. The structure is zero-dimensional and consists of sixteen water molecules and eight SbF6 clusters. In each SbF6 cluster, Sb is bonded in an octahedral geometry to six equivalent F atoms. All Sb–F bond lengths are 1.93 Å. F is bonded in a single-bond geometry to one Sb atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sb(PO3)4 by Materials Project

Sb(PO3)4 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Sb(PO3)4 sheet oriented in the (1, 0, 0) direction. Sb5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sb–O bond distances ranging from 2.13–2.36 Å. There are four inequivalent P+4.75+ sites. In the first P+4.75+ site, P+4.75+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.48–1.63 Å. In the second P+4.75+ site, P+4.75+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the third P+4.75+ site, P+4.75+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the fourth P+4.75+ site, P+4.75+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.51–1.59 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P+4.75+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P+4.75+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Sb5+ and one P+4.75+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one P+4.75+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Sb5+ and one P+4.75+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one Sb5+ and one P+4.75+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to one Sb5+ and one P+4.75+ atom. In the eighth O2- site, O2- is bonded in a distorted single-bond geometry to one Sb5+ and one P+4.75+ atom. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P+4.75+ atoms. In the tenth O2- site, O2- is bonded in a distorted single-bond geometry to one Sb5+ and one P+4.75+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P+4.75+ atoms. In the twelfth O2- site, O2- is bonded in a bent 120 degrees geometry to two P+4.75+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sb(PO3)5 by Materials Project

Sb(PO3)5 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Sb(PO3)5 sheet oriented in the (1, 0, 0) direction. Sb5+ is bonded to six O2- atoms to form SbO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sb–O bond distances ranging from 1.97–2.09 Å. There are five inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. There are a spread of P–O bond distances ranging from 1.46–1.69 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of P–O bond distances ranging from 1.53–1.60 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. There are a spread of P–O bond distances ranging from 1.45–1.69 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.47–1.72 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–50°. There are a spread of P–O bond distances ranging from 1.53–1.60 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sb5+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Sb5+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sb5+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sb(PO3)5 by Materials Project

Sb(PO3)5 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one Sb(PO3)5 sheet oriented in the (0, 0, 1) direction. Sb5+ is bonded to six O2- atoms to form SbO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Sb–O bond distances ranging from 1.94–2.06 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.47–1.74 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of P–O bond distances ranging from 1.46–1.70 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent SbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–49°. There are a spread of P–O bond distances ranging from 1.53–1.59 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Sb5+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sb5+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2023

High‐Throughput Study of Amorphous Stability and Optical Properties of Superlattice‐Like Ge–Sb–Te Thin Films

A high‐throughput ion beam sputtering system is used to synthesize compositional gradient superlattice‐like (SLL) thin film libraries of Ge–Sb–Te alloys over the entire phase diagram. Here, the optical properties and structural evolution of the Ge–Sb–Te combinatorial SLL thin film are investigated. A systematic screening over the annealing temperature, annealing time, and modulation period has elucidated the critical factors that affect the stability of the metastable phase and optical properties. It is found that amorphous stability and optical constant are highly dependent on the modulation period and chemical composition of the thin film. This data‐driven approach offers new perspectives for accelerating the development of new materials with excellent optical and amorphous stability and for exploring their mechanisms, by greatly expanding the dataset of Ge–Sb–Te alloys with SLL structures through high‐throughput experiments.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Tunable high spin Chern-number insulator phases in strained Sb monolayer

High spin Chern-number insulators (HSCI) have emerged as a novel 2D topological phase of condensed matter that is beyond the classification of topological quantum chemistry. The HSCI phase with two pairs of gapless helical edge states is robust even in the presence of spin–orbit coupling due to the protection of a “hidden” feature spectrum topology. Here, in this work, we report the observation of a semimetallic Sb monolayer carrying the same band topology as HSCI with the spin Chern number equal to 2. Our calculations further indicate a moderate lattice strain can make Sb monolayer an insulator or a semimetal with a tunable spin Chern number from 0 to 3. The results suggest strained Sb monolayers as a promising platform for exploring exotic properties of the HSCI topological matter.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Phase evolution and amorphous stability upon solid-state reaction in superlattice like Ge–Sb–Te combinatorial thin-film

In this paper, the superlattice-like (SLL) Ge–Sb–Te combinatorial thin films were prepared by using a high-throughput ion beam sputtering system. The phase evolution and amorphous stability of such films undergoing heat treatment as a function of the coating sequence and modulation period were systematically studied. The composition structure diagram was constructed via an automated process of data obtained by high-throughput synchrotron micro-X-ray diffraction and lab-based micro-X-ray fluorescence. Furthermore, the element distribution and microstructure in the depth direction of the SLL thin films were characterized with time-of-flight secondary ion mass spectrometry and transmission electron microscopy, respectively. These studies demonstrated that the coating sequence has a significant effect on the element distribution in the as-deposited SLL thin films and the structure of the final product upon solid-state reaction. Reducing the modulation period of the SLL thin film improves the stability of the amorphous Ge–Sb–Te phase. This work lays a solid foundation for the rational design of SLL Ge–Sb–Te thin films to improve their performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

High Thermoelectric Performance in 2D Sb 2 Te 3 and Bi 2 Te 3 Nanoplate Composites Enabled by Energy Carrier Filtering and Low Thermal Conductivity

Thermoelectrics are an important class of materials with great potential in alternative energy applications. In this study, two-dimensional (2D) nanoplates of the layered chalcogenides, Sb 2 Te 3 and Bi 2 Te 3 , are synthesized and composites of the two are investigated for their thermoelectric properties. The two materials, Sb 2 Te 3 and Bi 2 Te 3 , were synthesized as hexagonal, 2D nanoplates via a colloidal polyol route. The as-synthesized Sb 2 Te 3 and Bi 2 Te 3 vary drastically from one another in their lateral and vertical dimensions as revealed by scanning electron microscopy and atomic force microscopy. The single crystalline nanoplate nature is deduced by high-resolution transmission electron microscopy and selected area electron diffraction. Nanoplates have well-defined hexagonal facets as seen in the scanning and transmission electron microscopy images. The nanoplates were consolidated as an anisotropic nanostructured pellet via spark plasma sintering. Preferred orientation observed in the powder X-ray diffraction pattern and scanning electron microscopy images of the fractured pellets confirm the anisotropic structure of the nanoplates. Thermoelectric properties in the parallel and perpendicular directions were measured, revealing strong anisotropy with a significant reduction to thermal conductivity in the perpendicular direction due to increased phonon scattering at nanoplate interfaces. All compositions, except that of the 25% Bi 2 Te 3 nanoplate composite, behave as degenerate semiconductors with increasing electrical resistivity as the temperature increases. The Seebeck coefficient is also increased dramatically in the nanocomposites, the highest reaching 210 μV/K for 15% Bi 2 Te 3 . The increase in Seebeck is attributed to energy carrier filtering at the nanoplate interfaces. Overall, these enhanced thermoelectric properties lead to a drastic increase in the thermoelectric performance in the perpendicular direction, with zT ~ 1.26, for the 15% Bi 2 Te 3 nanoplate composite at 450 K.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Colloidal Synthesis of Palladium Nanocluster‐Decorated Cs 3 Sb 2 Cl 9 Perovskite Heterostructural Nanorods for Enhanced CO 2 Photoreduction

Developing efficient and sustainable photocatalysts for CO 2 reduction remains a significant challenge, particularly with environmentally benign materials. Here, in this study, we report the first one-step synthesis of metal–lead-free perovskite heterostructural nanocrystals by decorating Cs 3 Sb 2 Cl 9 perovskite nanorods with size-controlled Pd nanoclusters via a one-step hot-injection method. The resulting Pd-Cs 3 Sb 2 Cl 9 heteronanorods (HNRs) exhibit strong interfacial electronic coupling, enhanced charge separation, and excellent colloidal stability. Transient absorption spectroscopy and DFT calculations reveal a built-in electric field that drives directional electron transfer from the perovskite host to the Pd domains. Under UV irradiation, the Pd-Cs 3 Sb 2 Cl 9 HNRs demonstrate excellent CO 2 photoreduction activity with high CH 4 selectivity, achieving a record apparent quantum yield (AQY) of 2.62% among halide perovskite nanocrystal-based systems with a large electronic yield of 689.3 ± 12.2 µmol·g cat −1 . In situ spectroscopic monitoring and Gibbs free energy analysis further unveil a Pd-facilitated reaction pathway involving stabilization of key intermediates. This work introduces a new class of lead-free perovskite-based heterostructures through a facile one-step synthesis strategy and offers a new design principle for next-generation photocatalysts for solar fuel production.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2020

Clathrate XI K 58 Zn 122 Sb 207 : A New Branch on the Clathrate Family Tree

Abstract The compositional screening of K‐Zn‐Sb ternary system aided by machine learning, rapid exploratory synthesis using KH salt‐like precursor and in situ powder X‐ray diffraction yielded a novel clathrate type XI K 58 Zn 122 Sb 207 . This clathrate consists of a 3D Zn‐Sb framework hosting K + ions inside polyhedral cages, some of which are reminiscent of known clathrate types while others are unique to this structure type. The complex non‐centrosymmetric structure in the tetragonal space group was solved by means of single crystal X‐ray diffraction as a 6‐component twin due to pseudocubic symmetry and further confirmed by high‐resolution synchrotron powder X‐ray diffraction and state‐of‐the‐art scanning transmission electron microscopy. The electron‐precise composition of this clathrate yields narrow‐gap p ‐type semiconductor with extraordinarily low thermal conductivity due to displacement or “rattling” of K cations inside oversized cages and as well as to twinning, stacking faults and antiphase boundary defects.

Cox, Tori↗

DOE OSTI2020

Clathrate XI K 58 Zn 122 Sb 207 : A New Branch on the Clathrate Family Tree

Cox, Tori↗