Title: Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb 3 AlSb 3
A rare-earth-containing compound, ytterbium aluminium antimonide, Yb 3 AlSb 3 (Ca 3 AlAs 3 -type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb 2+ ) 3 [(Al 1− )( 1b – Sb 2− ) 2 ( 2b – Sb 1− )], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb 4 tetrahedra, [AlSb 2 Sb 2/2 ] 6− , with Yb 2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported. more »« less
Perez, Christopher J.; Wood, Maxwell; Ricci, Francesco; Yu, Guodong; Vo, Trinh; Bux, Sabah K.; Hautier, Geoffroy; Rignanese, Gian-Marco; Snyder, G. Jeffrey; Kauzlarich, Susan M.
(, Science Advances)
null
(Ed.)
The Zintl phases, Yb 14 M Sb 11 ( M = Mn, Mg, Al, Zn), are now some of the highest thermoelectric efficiency p-type materials with stability above 873 K. Yb 14 MnSb 11 gained prominence as the first p-type thermoelectric material to double the efficiency of SiGe alloy, the heritage material in radioisotope thermoelectric generators used to power NASA’s deep space exploration. This study investigates the solid solution of Yb 14 Mg 1− x Al x Sb 11 (0 ≤ x ≤ 1), which enables a full mapping of the metal-to-semiconductor transition. Using a combined theoretical and experimental approach, we show that a second, high valley degeneracy ( N v = 8) band is responsible for the groundbreaking performance of Yb 14 M Sb 11 . This multiband understanding of the properties provides insight into other thermoelectric systems (La 3− x Te 4 , SnTe, Ag 9 AlSe 6 , and Eu 9 CdSb 9 ), and the model predicts that an increase in carrier concentration can lead to zT > 1.5 in Yb 14 M Sb 11 systems.
Garay, Luis; Borgsmiller, Leah; Zavanelli, Duncan; Snyder, G Jeffrey; Fettinger, James; Kauzlarich, Susan
(, Dryad)
Abstract: Single crystals of Eu5-xYbxAl3Sb6 and Eu5-x-ySrxYbyAl3Sb6 were synthesized by flux methods and their structures determined by single-crystal X-ray diffraction, confirming the monoclinic C2/m symmetry. The Al content in these phases can be increased from 3 to 4 by metallurgical mixing of the elements to form polycrystalline powders. A comparative study of polycrystalline synthesized Eu5Al4Sb6 and its Sr- and Yb-substituted solid solutions, along with the pseudo-quinary phase Eu2.5Sr2Yb0.5Al4Sb6, is presented. Substituting Eu2+ with the more ionic Sr2+ enhances mobility and increases the magnitude of the Seebeck coefficient, while the more covalent Yb2+ drives the system metallic, lowering Seebeck values but improving zT to 0.8 at 873 K. The quinary phase further suppresses bipolar conduction, delaying the high-temperature downturn observed in both ternary solid solutions. Across all compositions, thermal conductivities remain exceptionally low (<1 W m⁻¹ K⁻¹), enabling promising figures of merit. Methods: The datasets (Powder X-ray diffraction and Thermoelectric property measurements) for the phase pure powders are provided. Compositions are provided below. Synthesis: Phase pure powders of composition Eu5.08Al4Sb4, Eu5Al4Sb6, Eu5-xAxAl4Sb6(A = Sr:x= 0.5, 2.5, 5; A = Yb:x= 0.5, 1, 1.5, 2, 5) and Eu2.5Sr2Yb0.5Al4Sb6Powder X-ray Diffraction (PXRD): PXRD data were collected at room temperature in air on ground single crystals and bulk powders of both solid solutions using a Bruker D8 Advance Eco diffractometer with Cu Kα radiation, 1000 W (40 kV, 25 mA), over 2θ = 15–85°, with a step size of 0.02°, and a scan rate of 1 s per step. Polycrystalline samples and ground single crystals were prepared on a zero-background holder using isopropanol. Thermal Conductivity Thermal Diffusivity (D) was measured on thin (1.19 to 1.2 mm thick) slices of Eu5-xAxAl4Sb6 (A = Sr and Yb) pellets using a Netzsch LFA 457 Microflash under a flow of high-purity Ar with a polished piece of Zr ribbon wrapped around the sample holder to act as an oxygen catcher. The thermal conductivity (κ) was determined using the equation: κ = D x ρ x Cp. The Dulong-Petit heat capacity value, Cp, was calculated from 3R/atom (R = gas constant). The pellets’ density (ρ) was measured in replicate using the Archimedes method with toluene as the liquid. All samples were > 95% of their theoretical crystallographic densities, calculated using the Arrhenius method. Electrical Resistivity and Seebeck A Linseis LSR-3 instrument was used to measure resistivity and the Seebeck coefficient employing the four-probe method from 350 K to 800 K under a He atmosphere. The instrument was calibrated with a constantan standard before use. The sample geometries were bar-shaped (10.5 mm x 4 mm x 2 mm) and polished before measurements with 8 mm probes. Multiple samples were measured to ensure reproducibility, and the data were cross-checked with measurements taken at Northwestern University. At Northwestern, electrical resistivity and Hall effect data were measured using a home-built Hall instrument. This set-up uses a four-point van der Pauw resistivity measurement with molybdenum leads and a current of 100 mA. Seebeck coefficient data were collected using a home-built two-probe Seebeck instrument with chromel/Nb thermocouples. TechnicalInfo: # One cation makes a difference: structure-thermoelectric interplay in pseudo-rock salt intermetallic Eu5-*x*A*x*Al3Sb6 (A = Sr and Yb) Dataset DOI: [10.5061/dryad.mkkwh71f1](https://doi.org/10.5061/dryad.mkkwh71f1) ## Description of the data and file structure **PXRD data collection (located in folder PXRD)** PXRD data were collected at room temperature in air on ground single crystals and bulk powders of both solid solutions using a Bruker D8 Advance Eco diffractometer with Cu Kα radiation, 1000 W (40 kV, 25 mA), over 2θ = 15–85°, with a step size of 0.02°, and a scan rate of 1 s per step. Polycrystalline samples were prepared on a zero-background holder using isopropanol. **Thermal Conductivity (located in folder TE properties)** Thermal Diffusivity (*D)* was measured on thin (1.19 to 1.2 mm thick) slices of Eu5-*x*A*x*Al4Sb6 (A = Sr and Yb) pellets using a Netzsch LFA 457 Microflash under a flow of high-purity Ar with a polished piece of Zr ribbon wrapped around the sample holder to act as an oxygen catcher. The thermal conductivity (κ) was determined using the equation: κ = *D* x ρ x C~p~. The Dulong-Petit heat capacity value, C~p~, was calculated from 3*R*/atom (R = gas constant). The pellets’ density (ρ) was measured in replicate using the Archimedes method with toluene as the liquid. All samples were > 95% of their theoretical crystallographic densities, calculated using the Arrhenius method. **Electrical Resistivity, Seebeck, and Hall Data Collection** A Linseis LSR-3 instrument was used to measure resistivity and the Seebeck coefficient employing the four-probe method from 350 K to 800 K under a He atmosphere. The instrument was calibrated with a constantan standard before use. The sample geometries were bar-shaped (10.5 mm x 4 mm x 2 mm) and polished before measurements with 8 mm probes. Multiple samples were measured to ensure reproducibility, and the data were cross-checked with measurements taken at Northwestern University. At Northwestern, electrical resistivity and Hall effect data were measured using a home-built Hall instrument. This set-up uses a four-point van der Pauw resistivity measurement with molybdenum leads and a current of 100 mA. Seebeck coefficient data were collected using a home-built two-probe Seebeck instrument with chromel/Nb thermocouples. ### Files and variables #### File: EuSrYbAlSb6_ChemMater_D.zip **Description:** There are 2 folders for each type of data: Powder X-ray Diffraction (**PXRD**) data for the polycrystalline synthesized samples indicated above; (**TE Properties**) Thermoelectric properties provides the electrical resistivity and Seebeck coefficient as a function of temperature for the polycrystalline samples. #### PXRD folder has 3 sub-folders: EuYbSr, Sr, Yb. The sub-folders contain dataset (.cvs) indicated by the cation composition of the polycrystalline synthesized sample. **Sub-Folder** **EuYbSr**: contains the PXRD data for Eu~2.5~Sr~2~Yb~0.5~Al~4~Sb~6~ **Sub-Folder** **Sr**: contains the PXRD data for Eu~2.5~Sr~2.5~Al~4~Sb~6~; Eu~4.5~Sr~0.5~Al~4~Sb~6~; Sr~5~Al~4~Sb~6~ **Sub-Folder** **Yb**: contains the PXRD data for Yb~5~Al~4~Sb~6;~ Eu~4~Yb~1~Al~4~Sb~6~; Eu~3~Yb~2~Al~4~Sb~6~; Eu~3.5~Yb~1.5~Al~4~Sb~6~; Eu~4.5~Yb~0.5~Al~4~Sb~6~ Each *.cvs dataset is indicated by the sample composition. Each dataset contains a header with the composition; column 1: 2-theta (degree); column 2: intensity (arbitrary units (a.u.)). #### **TE** **Properties** folder has 4 sub-folders: **Eu,** **EuYbSr**, **Sr**, **Yb**. The sub-folders contain dataset (*.cvs) indicated by the cation composition of the polycrystalline synthesized sample. Each *.cvs file has the composition of the element in the A column, and Temperature/K and Resistivity/ mOhm•cm; Seebeck Coefficient/ µV/K; Thermal Conductivity/W •m^-1^ •K^-1^ and ( if collected) carrier concentration/ h/cm^3^ and Hall mobility /cm^2^•V^-1^•s^-1^ **Sub-Folder Eu**: contains TE data for Eu~5~Al~4~Sb~6~; Eu~5.08~Al~4~Sb~6~; **Sub-Folder EuYbSr:** contains TE data for Eu~2.5~Sr~2.0~Yb~0.5~Al~4~Sb~6~ **Sub-Folder Sr:** contains TE data for Sr~5~Al~4~Sb~6~; Eu~2.5~Sr~2.5~Al~4~Sb~6~; Eu~4.5~Sr~0.5~Al~4~Sb~6~; **Sub-Folder Yb:** contains TE data for Yb~5~Al~4~Sb~6;~ Eu~4~Yb~1~Al~4~Sb~6~; Eu~3~Yb~2~Al~4~Sb~6~; Eu~3.5~Yb~1.5~Al~4~Sb~6~; Eu~4.5~Yb~0.5~Al~4~Sb~6~; ####
Garay, Luis; Gonzalez_Jimenez, Jose L; Fettinger, James C; Gunther, S Olivia; Branson, Jacob A; Minasian, Stefan G; Xie, Weiwei; Kauzlarich, Susan M
(, Inorganic Chemistry)
Zintl phases containing rare-earth metals have gained attention due to their magnetic, electronic, and thermoelectric properties. Eu5.08Al3Sb6 is a new structure type (monoclinic space group C2/m) that can be described as a pseudorock-salt EuSb motif with the Eu-centered Sb octahedra at the origin of the unit cell, and on the C-face center, containing either Eu (8%) or an Al4 tetrahedron modeled as a dual tetrahedron (37.5%). The complete solid solution of Eu5.08-x Sr x Al3Sb6 can be prepared; however, the cation totals vacillate from 5 to 5.24 depending on the Al content. Al K-edge XANES shows a shift to higher energy relative to the Al metal but at slightly lower energy relative to AlSb, indicating an intermediate oxidation state closer to +3 than 0. The lack of an Al K-edge shift with the incorporation of Sr suggests that changes in Sr content do not have a meaningful impact on the electronics of the Al tetrahedra. Investigation of the solid solution structures provides evidence for classifying this structure type as a polar intermetallic phase with variable composition. Magnetization measurements were collected for the solid solution and show complex magnetic ordering with competing ferromagnetic and antiferromagnetic interactions as the Sr content increases.
Rine, Jeremy; Yang, Yongqi; Shu, Zhixue; Zhao, Jianda; Xie, Weiwei; Kong, Tai
(, Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials)
A new compound, Ba 3 Ga 2 O 5 Cl 2 , isostructural with Ba 3 Fe 2 O 5 Cl 2 , was synthesized by solid-state reaction in air. Through single-crystal and powder X-ray diffraction analysis, the crystal structure was determined to be cubic with chiral space group I 2 1 3 and unit-cell parameter a = 9.928 (1) Å. The Ga 3+ ions in Ba 3 Ga 2 O 5 Cl 2 are coordinated by O atoms and form GaO 4 tetrahedra. Ten neighboring GaO 4 tetrahedra are further bridged through corner sharing and rotation along the body diagonal, producing the chiral structure. Magnetization measurements indicate temperature-independent diamagnetic behavior, which is qualitatively consistent with core diamagnetism from all the constituent elements.
Opara, Ivan Chinonso; Fettinger, James C; Star, Kurt E; Bux, Sabah K; Shen, Zihao; Taufour, Valentin; Kauzlarich, Susan M
(, Zeitschrift für anorganische und allgemeine Chemie)
The ternary phase, Yb14CdSb11, has been synthesized by flux and polycrystalline methods. The crystal structure is determined via single-crystal X-ray diffraction, revealing that it crystallizes in the Ca14AlSb11 structure type (I41/acd space group with unit cell parameters of a = 16.5962(2) & Aring; and c = 22.1346(5) & Aring;, 90 K, Z = 8, R1 = 2.65%, and wR2 = 4.58%). The polycrystalline form of the compound is synthesized from a stoichiometric reaction of Yb4Sb3, CdSb, Yb, and Sb. The elemental composition is confirmed using scanning electron microscopy and energy-dispersive spectroscopy, and phase purity is verified by powder X-ray diffraction. Thermoelectric measurements, including resistivity, Seebeck coefficient, thermal conductivity, Hall carrier concentration, and Hall mobility, are conducted from 300 to 1273 K. Yb14CdSb11 exhibits a peak zT = 0.90 at 1200 K. Carrier concentration and Hall mobility range from 6.99 x 1020-1.01 x 1021 cm-3 and 4.45-9.35 x 10-1 cm2 V-1 s-1, respectively. This carrier concentration is lower than that reported for the Zn or Mn analogs leading to a lower thermoelectric figure of merit at high temperatures. However, with appropriate doping, this phase should also be a promising p-type candidate for high-temperature energy conversion applications.
Shang, Rongqing, Nguyen, An T., He, Allan, and Kauzlarich, Susan M. Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb 3 AlSb 3. Retrieved from https://par.nsf.gov/biblio/10250592. Acta Crystallographica Section C Structural Chemistry 77.6 Web. doi:10.1107/S2053229621005192.
Shang, Rongqing, Nguyen, An T., He, Allan, & Kauzlarich, Susan M. Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb 3 AlSb 3. Acta Crystallographica Section C Structural Chemistry, 77 (6). Retrieved from https://par.nsf.gov/biblio/10250592. https://doi.org/10.1107/S2053229621005192
Shang, Rongqing, Nguyen, An T., He, Allan, and Kauzlarich, Susan M.
"Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb 3 AlSb 3". Acta Crystallographica Section C Structural Chemistry 77 (6). Country unknown/Code not available. https://doi.org/10.1107/S2053229621005192.https://par.nsf.gov/biblio/10250592.
@article{osti_10250592,
place = {Country unknown/Code not available},
title = {Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb 3 AlSb 3},
url = {https://par.nsf.gov/biblio/10250592},
DOI = {10.1107/S2053229621005192},
abstractNote = {A rare-earth-containing compound, ytterbium aluminium antimonide, Yb 3 AlSb 3 (Ca 3 AlAs 3 -type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb 2+ ) 3 [(Al 1− )( 1b – Sb 2− ) 2 ( 2b – Sb 1− )], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb 4 tetrahedra, [AlSb 2 Sb 2/2 ] 6− , with Yb 2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported.},
journal = {Acta Crystallographica Section C Structural Chemistry},
volume = {77},
number = {6},
author = {Shang, Rongqing and Nguyen, An T. and He, Allan and Kauzlarich, Susan M.},
editor = {null}
}
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