DOI: 10.5061/dryad.1zcrjdg3q
title: Optimization of the composition Eu5+xAl3+ySb6 and thermoelectric figure of merit

description: Eu5.08Al3Sb6 can be described as a pseudo rock salt-like “(Eu/Al4)Sb”
 structure. The polycrystalline synthesis of Eu5+xAl3+ySb6 was optimized.
 The compositions exhibit n-type transport behavior, ultra-low thermal
 conductivity, and a high Seebeck coefficient. The Eu5.08Al4Sb6 shows a
 promising zT of 0.8 at a temperature of 873 K.
description: # Optimization of the composition Eu5+xAl3+ySb6 and thermoelectric figure
 of merit
 [https://doi.org/10.5061/dryad.1zcrjdg3q](https://doi.org/10.5061/dryad.1zcrjdg3q) ## Description of the data and file structure The data sets are: (1) powder x-ray diffraction (PXRD): PXRD_ChemComm.zip, thermal gravimetric (TG)- Differential scanning calorimetry (DSC): TGDSC_ChemComm.zip and transport data: TransportData_ChemComm.zip **Powder X-ray Diffraction (PXRD):** PXRD_ChemComm.zip PXRD data were collected with a Bruker D8 Advance Eco Diffractometer using Cu Kα radiation from 2θ = 20° —80°  with a step size of 0.02 ˚ and scan rate of 1 s/step at room temperature in air. The polycrystalline samples were ground inside an Ar-filled glove box and plated on a zero-background holder with isopropanol. **Thermogravimetric (TG)/Differential Scanning Calorimetry (DSC):** TGDSC_ChemComm.zip Melting point studies of aluminum excess were done on polished pellet pieces of Eu5+*x*Al3+*y*Sb6 using TG/DSC (STA 449 F3 Jupiter, Netzsch) from room temperature up to 800°C with a heating rate of 10K/min under a 50 mL/min flow of Ar.  A piece of Aluminum metal (Aluminum shot, approx. 4-8mm (0.2-0.3in), Puratronic™, 99.999% (metals basis)) was used as a reference. **Thermal Conductivity:** TransportData_ChemComm.zip Thermal Diffusivity (*D) was measured on thin (1.19 to 1.2 mm thick) slices of Eu5+*x*Al3+*y*Sb6 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 from the equation: κ = *D* x ρ X Cp. All the pellets’ density (ρ) was measured multiple times using the Archimedes method using toluene as the liquid. All samples were &gt; 95% of their theoretical crystallographic densities, calculated using the Arrhenius method. **Transport Measurements:** TransportData_ChemComm.zip  A Linseis LSR-3 instrument was used to measure resistivity and Seebeck coefficient employing the four-probe method from 350K to 800K under He atmosphere. The sample geometries were bar-shaped ( 10.5mm x 4mm x 2mm) using 8 mm probes and polished before measurements. Multiple samples were measured to ensure reproducibility, and the data was cross-checked using measurements at JPL and Northwestern. The Seebeck coefficient was measured using a light pulse technique as described above using W/Nb thermocouples. Electrical resistivity (ρ) was measured using the van der Pauw (VDP) technique with a current of 10 mA. Electrical resistivity and Hall effect data were measured using a home-built Hall effect instrument for the samples measured at Northwestern.1 This set-up utilizes a four-point Van der Pauw resistivity measurement with molybdenum leads and a current of 100 mA. Seebeck coefficient data was collected using a home-built two-probe Seebeck instrument with chromel/Nb thermocouples. ### Files and variables #### File: PXRD_ChemComm.zip **Description:** Powder X-ray diffraction data files, collected according to the description provided above. **Variables:** x, y where x = two-theta (˚) and y = X-ray diffraction Intensity (arbitrary units) **Files:** Eu5_08Al3_3Sb6.xy = sample composition Eu5.08Al3.3Sb6 Eu5_08Al4Sb6.xy = sample composition Eu4.08Al4Sb6 Eu5Al3_3Sb6.xy = sample composiiton Eu5Al3.3Sb6 Eu5Al3Sb6.xy = sample composition, Eu5Al3Sb6 Eu5Al4Sb6.xy = sample composition Eu5Al4Sb6 #### File: TGDSC_ChemComm.zip **Description:** Thermogravimetric and differential scanning calorimetry data collected according to the description provided above. **Variables:** Temperature/˚C; Time/min; DSC/(mW/mg); Mass/%; Gas Flow (purge2)/(ml/min); Gas Flow(protective)/(ml/min); Sensit./(uV/mW) **Files:** ExpDat_Aluminum_shot_800C_1.csv = (segment 1) experimental data for aluminum shot taken from 20 ˚C to 800 ˚C. ExpDat_Aluminum_shot_800C_2.csv = (segment 2) experimental data for aluminum shot taken from 800 ˚C to 20˚C. ExpDat_Eu5_08Al3_3Sb6_800C_1.csv = (segment 1) experimental data for sample composition Eu5.08Al3.3Sb6 taken from 20 ˚C to 800 ˚C. ExpDat_Eu5_08Al3_3Sb6_800C_2.csv = (segment 2) experimental data for sample composition Eu5.08Al3.3Sb6 taken from 800 ˚C to 20˚C. ExpDat_Eu5_08Al4Sb6_800C_1.csv = (segment 1) experimental data for sample composition Eu5.08Al4Sb6 taken from 20 ˚C to 800 ˚C. ExpDat_Eu5_08Al4Sb6_800C-2.csv = (segment 2) experimental data for sample composition Eu5.08Al4Sb6 taken from 800 ˚C to 20˚C. ExpDat_Eu5Al3_3Sb6_800C_1.csv = (segment 1) experimental data for sample composition Eu5Al3.3Sb6 taken from 20 ˚C to 800 ˚C. ExpDat_Eu5Al3_3Sb6_800C_2.csv = (segment 2) experimental data for sample composition Eu5Al3.3Sb6 taken from 800 ˚C to 20 ˚C. ExpDat_Eu5Al4Sb6_800C_1.csv = (segment 1) experimental data for sample composition Eu5Al4Sb6 taken from 20 ˚C to 800 ˚C. ExpDat_Eu5Al4Sb6_800C_2.csv = (segment 2) experimental data for sample composition Eu5Al4Sb6 taken from 800 ˚C to 20 ˚C. #### File: TransportData_ChemComm.zip **Description:** Hall data and Seebeck data files containing Temperature dependent Hall resistivity, mobility, resistivity, Seebeck. *Variables for Hall Data:* Sample thickness in mm; Temperature/(˚C) ; Temperature/(K); Resistivity/(mohm.cm); Conductivity/(S/cm); Carrier Concentration/(/cm3); Hall Mobility/ (cm2/Vs); Hall Resistivity = R_H/(cm3/C); temperature for resistance = T_Res/(˚C); temperature for Hall data collection = T_Hall/(˚C); Resistance Standard deviation = Res*_*Std/(%); Hall resistance standard deviation = RH*_*Std/(%); Hall mobility standard deviation = muH Std/(%); Applied magnetic field = B field/(Gauss); applied current for resistivity = I_Res/(mA); van der Pauw ration = vdP ratio; resistivity time = Res. Time= time and date for the measurement; Hall time = Hall. Time = time and date for the Hall measurement; lead resistance for the 4 leads = Lead Res. 1, Lead Res. 2, Lead Res. 3, and Lead Res. 4 in Ohm; Probe to ground resistance = Probe-GND REsistance/(Ohm); thermocouple 1 = TC1/(˚C) was not used; thermocouple 2 = TC2/(˚C) was not used. **Variables for Seebeck Data**: Temperature = T/(˚C); Seebeck coefficient = seebfit/(uV/K) **Files:** Eu5_08Al3_3Sb6_HallData.csv = Hall data for sample composition Eu5.08Al3.3Sb6 taken from 20 ˚C to 550 ˚C. Eu5_08Al4Sb6_HallData.csv = Hall data for sample composition Eu5.08Al4Sb6 taken from 20˚C to 550 ˚C. Eu5Al3_3Sb6_HallData.csv = Hall data for sample composition Eu5Al3.3Sb6 taken from 20˚C to 550 ˚C. Eu5Al4Sb6_HallData.csv= Hall data for sample composition Eu5Al4Sb6 taken from 20˚C to 550˚C. Eu5_08Al3_3Sb6_Seebeck.csv = Seebeck data for sample composition Eu5.08Al3.3Sb6 taken from 50 ˚C to 600 ˚C. Eu5_08Al4Sb6_Seebeck.csv = Seebeck data for sample composition Eu5.08Al5Sb6 taken from 50 ˚C to 600 ˚C. Eu5Al3_3Sb6_Seebeck.csv = Seebeck data for sample composition Eu5Al3.3Sb6 taken from 50˚C to 600 ˚C. Eu5Al4Sb6_Seebeck.csv = Seebeck data for sample composition Eu5Al4Sb6 taken from 50˚C to 600 ˚C. **ThermalConductivity Folder:** thermal diffusivity data of all samples; conversion to thermal conductivity data provided in LJGEu5Al3Sb6*_*TD_TC.xlsx file. **Variables:** Sample thickness = #Thickness_RT/(mm); sample diameter = #Diameter/(mm); argon gas flow = #Gas flow/(ml/min); shot number; data collection time = #Time/(min); temperature = #Temperature/(˚C); diffusivity data = #Diffusivity/(mm^2/s); standard deviation based on 3 shots = #Std_Dev/(mm^2/s) Files:  Eu5_08Al3_3Sb6TD.csv = thermal diffusivity data for sample composition Eu5.08Al3.3Sb6 taken from 10 ˚C to 550 ˚C. Eu5_08Al4Sb6_TD.csv = thermal diffusivity data for sample composition Eu5.08Al4Sb6 taken from 10 ˚C to 550 ˚C. Eu5Al3_3Sb6_TD.csv = thermal diffusivity data for sample composition Eu5.08Al3.3Sb6 taken from 10 ˚C to 550 ˚C. Eu5Al4Sb6_TD.csv = thermal diffusivity data for sample composition Eu5Al4Sb6 taken from 10 ˚C to 550 ˚C. LJGEu5Al3Sb6_TD_TC.xlsx = Data file providing the conversion of all compositions from thermal diffusivity data to thermal conductivity values. All compositions indicated with headers with temperature = T/(˚C); temperature = T/(K); diffusivity (mm2/s); density /(gm/cm3); Heat Capacity/ ; Thermal Conductivity/(W/mK); Thermal Conductivity/(mW/cmK);