DOI: 10.5061/dryad.mkkwh71f1
title: One cation makes a difference: structure-thermoelectric interplay in pseudo-rock salt intermetallic Eu5-<em>x</em>A<em>x</em>Al3Sb6 (A = Sr and Yb)

description: 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 (&lt;1 W m⁻¹ K⁻¹), enabling promising figures
 of merit.
description: The datasets (Powder X-ray diffraction and Thermoelectric
 property measurements) for the phase pure powders are provided.
 Compositions are provided below.
 <strong>Synthesis</strong>: Phase pure powders of
 composition
 <strong>Eu<sub>5.08</sub>Al<sub>4</sub>Sb<sub>4</sub>, Eu<sub>5</sub>Al<sub>4</sub>Sb<sub>6</sub></strong>, <strong>Eu<sub>5-<em>x</em></sub>A<em><sub>x</sub></em>Al<sub>4</sub>Sb<sub>6</sub></strong> <strong>(A = Sr:</strong> <em><strong>x</strong></em> <strong>= 0.5, 2.5, 5; A = Yb:</strong> <em><strong>x</strong></em> <strong>= 0.5, 1, 1.5, 2, 5) and Eu<sub>2.5</sub>Sr<sub>2</sub>Yb<sub>0.5</sub>Al<sub>4</sub>Sb<sub>6</sub></strong> <strong>Powder X-ray Diffraction (PXRD):</strong> 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. <strong>Thermal Conductivity</strong> Thermal Diffusivity (<em>D)</em> was measured on thin (1.19 to 1.2 mm thick) slices of Eu<sub>5-<em>x</em>A<em>x</em>Al4</sub>Sb<sub>6</sub> (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 = <em>D</em> x ρ x C<sub>p</sub>. The Dulong-Petit heat capacity value, C<sub>p</sub>, was calculated from 3<em>R</em>/atom (R = gas constant).  The pellets’ density (ρ) was measured in replicate using the Archimedes method with toluene as the liquid. All samples were &gt; 95% of their theoretical crystallographic densities, calculated using the Arrhenius method. <strong>Electrical Resistivity and Seebeck</strong> 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.
description: # 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 &gt; 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~; ####