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1. Magnetism and Thermoelectric Properties of the Zintl Semiconductor: Eu ₂₁ Zn ₄ As ₁₈

   https://doi.org/10.1021/acs.chemmater.4c02200  

   Islam, Md Minhajul; Wróblewska, Maria; Shen, Zihao; Toberer, Eric S; Taufour, Valentin; Kauzlarich, Susan M (December 2024, Chemistry of Materials)

   Compositional diversity and intriguing structural features have made Zintl phases excellent candidates as thermoelectric materials. Zintl phase with 21-4-18 composition has shown high thermoelectric performance in the mid- to high-temperature ranges. The complex crystal structure and favorable transport properties of these compounds indicate the potential for high thermoelectric efficiency. Arsenic-based Eu21Zn4As18, belonging to the Ca21Mn4Sb18 structure type, exhibits a semiconductor-like p-type transport behavior and has a calculated band gap of 0.49 eV. The compound is paramagnetic at high temperatures, with an antiferromagnetic transition occurring at T-N = similar to 10 K. The moment obtained from the Curie-Weiss data fit aligns with Eu2+ ions. At the same time, the field-dependent measurement at 2 K indicates complex magnetic ordering with a saturation moment consistent with Eu2+ ions. Pristine Eu21Zn4As18 exhibits an ultralow lattice thermal conductivity of 0.40 W m(-1) K-1 at 873 K. Electronic transport properties measurement shows evidence of bipolar conduction across much of the measured temperature range (450-780 K). However, the Seebeck coefficient remains extremely high (>440 mu V K-1) across this range, indicating the potential for high zT if an appropriate dopant is found. This work represents the first report on the temperature-dependent thermal conductivity, Seebeck coefficient, and thermoelectric efficiency of the arsenic-containing Zintl phase with 21-4-18 composition, showcasing its promise for further optimization of the thermoelectric performance. 

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2. Eu ₁₁ Zn ₄ Sn ₂ As ₁₂ : A Ferromagnetic Zintl Semiconductor with a Layered Structure Featuring Extended Zn ₄ As ₆ Sheets and Ethane-like Sn ₂ As ₆ Units

   https://doi.org/10.1021/acs.chemmater.8b02749  

   Devlin, Kasey P.; Kazem, Nasrin; Zaikina, Julia V.; Cooley, Joya A.; Badger, Jackson R.; Fettinger, James C.; Taufour, Valentin; Kauzlarich, Susan M. (September 2018, Chemistry of Materials)
3. Role of Copper Doping in Modulating the Thermoelectric Properties of Eu ₁₁ Zn ₄ Sn ₂ As ₁₂

   https://doi.org/10.1021/acsaem.6c00664  

   Miramontes_Ruiz, Christopher; Wróblewska, Maria; Toberer, Eric S; Kauzlarich, Susan M (June 2026, ACS Applied Energy Materials)
4. Complex Structural Disorder in Thermoelectric Zintl Phases Eu ₂₁ M ₄ As ₁₈ ( M = Mn, Zn)

   https://doi.org/10.1002/zaac.202500070  

   Ishtiyak, Mohd; Watts, Spencer R; Pokhvata, Olha; Kandabadage, Thimira; Baranets, Sviatoslav (September 2025, Zeitschrift für anorganische und allgemeine Chemie)

   Ternary Zintl arsenides Eu₂₁Mn₄As₁₈, Eu₂₁Zn₄As₁₈, and quaternary solid solution Eu₂₁Mn₄As_15.4Sb_2.6have been synthesized and structurally characterized using single‐crystal X‐ray diffraction. Eu₂₁Mn₄As₁₈and Eu₂₁Mn₄As_15.4Sb_2.6are reported here for the first time, whereas new structural insights are presented for the previously known Eu₂₁Zn₄As₁₈. All title compounds crystallize in the Sr₂₁Mn₄Sb₁₈structure type (space groupC2/m) and exhibit pronounced positional disorder affecting both cationic and anionic sites. This includes disorder on Eu atoms and As₂dimers, as well as splitM(M = Mn, Zn) sites within the anionic [M₈As₂₂]⁴⁸⁻clusters. Despite the disorder, the Zintl concept remains applicable to the novel Eu₂₁Mn₄As₁₈phase, and the charge‐balanced composition can be expressed as 2 × Eu₂₁Mn₄As₁₈= [Eu²⁺]₄₂{[Mn₈As₂₂]^48‐}{[As₂]^4‐}₃[As^3‐]₈. Electronic structure calculations performed on the disorder‐free model of Eu₂₁Zn₄As₁₈predict a bandgap of ≈1.1 eV. 

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5. Data from: Role of copper doping in modulating the thermoelectric properties of Eu₁₁Zn₄Sn₂As₁₂

   https://doi.org/10.5061/dryad.d7wm37qgk  

   Miramontes, Christopher; Wróblewska, Maria; Toberer, Eric; Kauzlarich, Susan (January 2026, Dryad)

   Abstract: Eu11Zn4Sn2As12 is a p-type semiconductor that has been proposed to undergo 3D-to-2D electronic transport as the carrier concentration increases. This commensurately modulated structure in space group R3̅m has been shown to improve its thermoelectric properties upon Na doping, concurrently decreasing electrical resistivity while maintaining a large Seebeck coefficient. In this study, Eu11Zn4Sn2As12 was doped with Cu with the goal of substituting in the [Zn2As3]5− defect hexagonal layers to improve electrical transport. Thermal conductivity, carrier concentration, mobility, electrical resistivity, and the Seebeck coefficients as a function of temperature from 300 to 600 K were measured as a function of Cu content. A maximum zT600K of 0.24 for Eu11Zn4-xCuxSn2As12, x = 0.6, was reached. Methods: The samples, Eu₁₁Zn_4-xCuxSn2As₁₂ (x = 0.0, 0.2, 0.4, 0.6) were synthesized and analyzed by powder X-ray diffraction and pressed into dense pellets by Spark Plasma Sintering. The pellets were ≥ 98 % dense by the Archimedes method. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy were obtained and provided in the publication's supporting information. Thermal conductivity, carrier concentration, mobility, electrical resistivity, and the Seebeck coefficients were collected as a function of temperature from 300 to 600 K. Powder X-Ray Diffraction: The sintered sample pellets were ground in a mortar and pestle for PXRD analysis. Samples were plated onto a zero-background X-ray quartz plate, and diffraction was performed with a Bruker D8 Advance Eco diffractometer with Cu Kα radiation (λ = 1.5405 Å) at 40 kV and 25 mA at room temperature. Data was collected with a 0.01 step size and a 2θ range from 20° - 80°. Thermal Conductivity: A Netzsch Laser Flash Analysis (LFA) 475 Microflash instrument was used to measure the thermal diffusivity of the pellets (polished flat and parallel and sprayed with graphite to ensure laser absorption). Thermal conductivity was calculated using thermal diffusivity using the equation κ = λδCp, where κ is thermal conductivity, λ is thermal diffusivity, δ is the sample density, and Cp is the Dulong-Petit heat capacity. Seebeck, Resistivity, and Hall Measurement: Seebeck coefficient measurements were obtained from a custom-built instrument under nitrogen atmosphere and pressure of 300 Torr from 300 to 600K. Resistivity and Hall measurements were obtained with an in-house-built instrument using the van der Pauw geometry. Hall coefficient measurements used 80 mA current and 1 T magnetic field. TechnicalInfo: # Data from: Role of copper doping in modulating the thermoelectric properties of Eu~11~Zn~4~Sn~2~As~12~ Dataset DOI: [10.5061/dryad.d7wm37qgk](https://doi.org/10.5061/dryad.d7wm37qgk) ## Description of the data and file structure The folder entitled Eu11Zn4Sn2As12_Cu_Doping.zip contains 4 *.csv* files, one for each composition of Eu~11~Zn~4−x~*Cu~x~Sn~2~As~12~ (*x* = 0.0, 0.2, 0.4, 0.6) The data are provided in column with room Temperature powder X-ray diffraction, electrical resistivity as a function of temperature (300-600 K), Seebeck coefficients as a function of temperature (300-600 K), thermal conductivity as a function of temperature (300-600 K), carrier concentration as a function of temperature (300-600 K), and Hall mobility as a function of temperature (300-600 K). #### Folder: Eu11Zn4Sn2As12_Cu_Doping.zip **Description:** Contains 4 *.csv files: * Eu11Zn4-xCuxSn2As12_x=0 * Eu11Zn4-xCuxSn2As12_x=0.2 * Eu11Zn4-xCuxSn2As12_x=0.4 * Eu11Zn4-xCuxSn2As12_x=0.6 ## Files and variables File: Eu11Eu4-xCuxSn2As12_x=0.0\ Room temperature powder X-ray diffraction (PXRD) data are provided in columns A and B, with two-theta/degree (column A) and intensity/arbitrary units (au) (column B). Column C is empty. Resistivity vs Temperature data are provided in columns D and E), with Temperature/K (column D) and resistivity/mOhm cm (column E). Column F is empty. Seebeck coefficient vs Temperature data is provided in Columns G and H, with Temperature/K and Seebeck coefficient/µV/K. Column I is empty. Thermal conductivity vs Temperature data are provided in columns J and K, with Temperature/K (column J) and thermal conductivity/W/m K (column K). Column L is empty. Carrier concentration vs Temperature data are found in columns M and N, with Temperature/K (column M) and carrier concentration/h^+^ cm ^-3^ (column N). Hall mobility vs Temperature is provided in columns O and P, with Temperature/K (column O) and Hall mobility/cm^2^ V ^-1^ s ^-1^ (column P). File: Eu11Eu4-xCuxSn2As12_x=0.2\ Room temperature powder X-ray diffraction (PXRD) data are provided in columns A and B, with two-theta/degree (column A) and intensity/arbitrary units (au) (column B). Column C is empty. Resistivity vs Temperature data are provided in columns D and E), with Temperature/K (column D) and resistivity/mOhm cm (column E). Column F is empty. Seebeck coefficient vs Temperature data (measured twice to show reproducibiity) is provided in Columns G-J, with Temperature/K and Seebeck coefficient/µV/K. Column K is empty. Thermal conductivity vs Temperature data are provided in columns L and M, with Temperature/K (column L) and thermal conductivity/W/m K (column M). Column N is empty. Carrier concentration vs Temperature data are found in columns O and P, with Temperature/K (column O) and carrier concentration/h^+^ cm ^-3^ (column P). Hall mobility vs Temperature is provided in columns Q and R, with Temperature/K (column Q) and Hall mobility/cm^2^ V ^-1^ s ^-1^ (column R). File: Eu11Zn4-xCuxSn2As12_x=0.4\ Room temperature powder X-ray diffraction (PXRD) data are provided in columns A and B, with two-theta/degree (column A) and intensity/arbitrary units (au) (column B). Column C is empty. Resistivity vs Temperature data are provided in columns D and E), with Temperature/K (column D) and resistivity/mOhm cm (column E). Column F is empty. Seebeck coefficient vs Temperature data (measured twice to show reproducibiity) is provided in Columns G-J, with Temperature/K and Seebeck coefficient/µV/K. Column K is empty. Thermal conductivity vs Temperature data are provided in columns L and M, with Temperature/K (column L) and thermal conductivity/W/m K (column M). Column N is empty. Carrier concentration vs Temperature data are found in columns O and P, with Temperature/K (column O) and carrier concentration/h^+^ cm ^-3^ (column P). Hall mobility vs Temperature is provided in columns Q and R, with Temperature/K (column Q) and Hall mobility/cm^2^ V ^-1^ s ^-1^ (column R). File: Eu11Zn4-xCuxSn2As12_x=0.6\ Room temperature powder X-ray diffraction (PXRD) data are provided in columns A and B, with two-theta/degree (column A) and intensity/arbitrary units (au) (column B). Column C is empty. Resistivity vs Temperature data are provided in columns D and E), with Temperature/K (column D) and resistivity/mOhm cm (column E). Column F is empty. Seebeck coefficient vs Temperature data is provided in Columns G and H, with Temperature/K and Seebeck coefficient/µV/K. Column I is empty. Thermal conductivity vs Temperature data are provided in columns J and K, with Temperature/K (column J) and thermal conductivity/W/m K (column K). Column L is empty. Carrier concentration vs Temperature data are found in columns M and N, with Temperature/K (column M) and carrier concentration/h^+^ cm ^-3^ (column N). Hall mobility vs Temperature is provided in columns O and P, with Temperature/K (column O) and Hall mobility/cm^2^ V ^-1^ s ^-1^ (column P). 

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