DOI: 10.5061/dryad.37pvmcvzv
title: Data from: Diffuson-driven lattice thermal conductivity in Zintl arsenides: disrupting mass-thermal conductivity relation for high thermoelectric performance

description: Zintl compounds of the Ca14AlSb11 structure type, especially Yb14MSb11 (M
 = Mg, Mn, Zn), have emerged as leading contenders for high-temperature
 thermoelectric applications because of their very low thermal conductivity
 and excellent electronic properties. In comparison, the lighter
 arsenic-based compounds have received less attention, as they are
 generally thought to have poor thermoelectric performance due to higher
 thermal conductivity. In this study, we synthesized 4 compounds, Eu14MAs11
 (M = Mg, Zn, Cd) and Eu14Zn1.2As11, and refined their powder diffraction
 patterns using Rietveld refinement. We measured the transport properties
 of these compounds to demonstrate that diffuson conduction is common
 across these compositions, resulting in a lattice thermal conductivity of
 about 0.55 W m-1 K-1 at 298 K and challenging the usual relationship
 between mass and lattice thermal conductivity. The combination of low
 thermal conductivity and high valley degeneracy enables these materials to
 reach impressive thermoelectric performance, with Eu14MgAs11 achieving a
 maximum zT of 1.3 at 1250 K.
description: # Data from: Diffuson-driven lattice thermal conductivity in Zintl
 arsenides: disrupting mass-thermal conductivity relation for high
 thermoelectric performance Dataset DOI:
 [10.5061/dryad.37pvmcvzv](https://doi.org/10.5061/dryad.37pvmcvzv) ##
 Description of the data and file structure Four compounds were synthesized
 and characterized: Eu~14~MgAs~11~, Eu~14~CdAs~11~, Eu~14~Zn~1.2~As~11~,
 Eu~14~ZnAs~11~. **Synthesis:** The compounds were synthesized with binary
 phases, EuA and *M*~2~As~3~ (*M* = Mg, Cd, Zn). For the Eu~14~MgAs~11~
 phase, EuH~2~ was also employed to achieve phase pure product.
 Stoichiometric mixtures were milled in a 650 cm^3^ steel grinding vial
 with two 12.7 mm balls employing a SPEX mixer-mill. The resulting powder
 was transferred to a tantalum tube and sealed using an Ar-fille arc
 welder. The tantalum tube was further sealed in a fused silica tube under
 vacuum and annealed in a furnace at 1100 °C for 96 h. **Powder X-ray
 Diffraction (PXRD):** The powder sample was ground with a mortar and
 pestle and sieved through a 100-mesh screen for X-ray diffraction
 measurements. The fine powder was taken on a zero background off-axis
 SiO~2~ plate by using solvent-smearing techniques with ethanol. PXRD
 experiments were performed using a Bruker D8 ADVANCE ECO instrument at
 room temperature. Data were collected from 15° to 80° 2θ with a step size
 of 0.01638° 2θ using Cu K~α1~ and K~α2~ radiations with Ni filter to
 remove Cu K~b~. **Spark Plasma Sintering:** The finely ground powder was
 loaded into a 12.7 mm internal diameter graphite die (Cal Nano) with
 graphite plungers and graphite foils on each side inside an argon
 atmosphere within the glove box. The die was then inserted into a spark
 plasma sintering device (Dr. Lab Sinter Jr., Fuji Corp.) for pressing
 under a 50% Air/Ar environment. The powder was heated to 850 °C over 10
 minutes, with the applied force increasing from 6 to 10.5 kN during this
 period. It was then sintered to 900 °C in 1 minute and held at this
 temperature for 30 minutes to consolidate the sample. The resulting
 pellets achieved densities greater than 98% of the theoretical density, as
 measured by the Archimedes method. **Resistivity Measurements:**
 Resistivity measurements were conducted on densified pellets with a
 diameter of 12.7 mm at the Jet Propulsion Laboratory (JPL) using a Van der
 Pauw method. Resistivity was converting into conductivity for the data
 analysis. **Seebeck Coefficient Measurements:** The Seebeck coefficient
 was measured at the Jet Propulsion Laboratory (JPL) using a custom-built
 apparatus generating light pulses via the light-pipe methods with
 tungsten-niobium thermocouples under high vacuum. **Thermal Conductivity
 Measurements:** The thermal diffusivity of the pressed pellet was measured
 from 298 K to 1272 K using a Netzsch LFA-457 unit. The dense pellet was
 polished to achieve a uniform, consistent thickness. It was coated with
 graphite to ensure high emissivity of the laser flash. The total thermal
 conductivity, k, was calculated from the equation k = DC~p~*d*, where D is
 the measured diffusivity; C~p~ is the heat capacity; *d* is the room
 temperature density obtained from the Archimedes method. Heat capacity was
 estimated using the Dulong−Petit law. **Carrier Concentration and Hall
 Mobility:** Hall coefficient measurements were conducted on densified
 pellets with a diameter of 12.7 mm at the Jet Propulsion Laboratory (JPL)
 using a Van der Pauw method with a applied magnetic field of 1.0 T and a
 current of 100 mA. ### Files and variables #### File: Data.zip **File
 Description:** The file contains 4 data sets corresponding to the 4
 compositions measured, saved as both *.xlsx and *.csv files. The files are
 named according to the composition: Eu~14~MgAs~11~, Eu~14~CdAs~11~,
 Eu~14~ZnAs~11~, and Eu~14~Zn~1.2~As~11~ **Data Description:** Each file
 contains PXRD (2-theta (°), intensity (arbitrary units)); Conductivity vs
 T (Temperature (K), Conductivity (S cm ^-1^); Seebeck vs T (Temperature
 (K), Seebeck Coefficient (µV/K)); Carrier Concentration vs T (Temperature
 (K), Carrier Concentration (h+ , cm ^-3^)), and Hall Mobility vs T
 (Temperature (K), Hall Mobility (cm^2^ V ^-1^ s ^-1^).