One cation makes a difference: structure-thermoelectric interplay in pseudo-rock salt intermetallic Eu5-xAxAl3Sb6 (A = Sr and Yb)
Data files
Feb 17, 2026 version files 203.98 KB
-
EuSrYbAlSb6_ChemMater_D.zip
199.60 KB
-
README.md
4.37 KB
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.
Dataset DOI: 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-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, 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 Eu2.5Sr2Yb0.5Al4Sb6
Sub-Folder Sr: contains the PXRD data for Eu2.5Sr2.5Al4Sb6; Eu4.5Sr0.5Al4Sb6; Sr5Al4Sb6
Sub-Folder Yb: contains the PXRD data for Yb5Al4Sb6; Eu4Yb1Al4Sb6; Eu3Yb2Al4Sb6; Eu3.5Yb1.5Al4Sb6; Eu4.5Yb0.5Al4Sb6
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/cm3 and Hall mobility /cm2•V-1•s-1
Sub-Folder Eu: contains TE data for Eu5Al4Sb6; Eu5.08Al4Sb6;
Sub-Folder EuYbSr: contains TE data for Eu2.5Sr2.0Yb0.5Al4Sb6
Sub-Folder Sr: contains TE data for Sr5Al4Sb6; Eu2.5Sr2.5Al4Sb6; Eu4.5Sr0.5Al4Sb6;
Sub-Folder Yb: contains TE data for Yb5Al4Sb6; Eu4Yb1Al4Sb6; Eu3Yb2Al4Sb6; Eu3.5Yb1.5Al4Sb6; Eu4.5Yb0.5Al4Sb6;
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 Eu2.5Sr2Yb0.5Al4Sb6
Powder 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.