Skutterudite Compounds Research Articles

Exploring novel filled skutterudites: A comprehensive DFT Modeling study on electronic, magnetic, curie temperature, elastic, thermal, and thermoelectric properties

Embarking on a captivating journey through the intricacies of two groundbreaking Skutterudite compounds, BaMn4X12 (X = As, Sb), employing first-principles calculations based on the Generalized Gradient Approximation (GGA) and modified Beck-Johnson approximation (mBJ) of density functional theory (DFT), has unveiled intriguing revelations. These compounds showcase exceptional stability within the ferromagnetic phase of the BaMn4As12 and BaMn4Sb12 cubic-type structure, boasting equilibrium lattice parameters of 0.933 nm for BaMn4As12 and 0.92 nm for BaMn4Sb12. The electronic properties point to their half-metallic nature, and a thorough analysis of elastic properties confirms their remarkable stability, high rigidity, anisotropy, and minimal deformation, exhibiting a ductile behavior. The magnetic properties analysis underscores the ferromagnetic state of both compounds, revealing a computed total magnetic moment of 4.76 μB for BaMn4As12 and 4.60 μB for BaMn4Sb12. Finally, our examination of the thermodynamic parameters of these compounds, conducted across temperatures ranging from 0 to 800 K and pressures from 0 to 40 GPa using the quasi-harmonic Debye model, underscores their immense potential for diverse applications. These findings inspire excitement, showcasing the promising avenues for the utilization of BaMn4X12 (X = As, Sb) compounds in various fields, including materials science, engineering, and technology. Additionally, the fundamental application of semi-classical Boltzmann theory has been incorporated into the advanced framework of BoltzTraP to investigate its transport coefficients. Hence, the general inclination of these specific compounds may support their potential for various applications in sustainable thermoelectrics, spintronics features, and more.

A comprehensive study of the magnetic, electronic, mechanical, and thermoelectric properties of novel filled skutterudites KFe4Ge12 and KFe4P12 using ab-initio calculations

This study provides a comprehensive exploration of the multifaceted properties and stability of KFe₄Ge₁₂ and KFe₄P₁₂ skutterudite compounds. Advanced Density Functional Theory (DFT) techniques are utilized to delve into their structural, magnetoelectronic, elastic, thermophysical, and thermoelectric attributes, all while focusing on their performance under the influence of ferromagnetism. Our investigations reveal that these skutterudites closely align with similar materials in terms of structural stability, showcasing robust structural integrity. We meticulously examined the magnetic properties, and ferromagnetic phases emerged as the most thermodynamically stable, requiring minimal energy input. Moving to the realm of magnetoelectronic, electronic band profiles were calculated using the Generalized Gradient Approximation (GGA) and the modified Becke-Johnson method (mBJ). Remarkably, both compounds exhibit metallic behavior and substantial spin polarization potential, promising exciting applications in spintronic devices. Elastic properties were scrutinized, affirming their mechanical stability, while thermophysical analysis highlighted their thermodynamic robustness. Notably, these materials demonstrated remarkable thermoelectric attributes, with the BoltzTraP code unveiling impressive Seebeck coefficients and electrical conductivities. These findings underline their immense potential for deployment in solid-state devices, emphasizing their strength in thermoelectrics. This study paves the way for exciting advancements in materials science and applications across various domains. Throughout our investigations, we discovered that these skutterudites exhibit a high degree of structural stability, showcasing robust integrity in their composition. Moreover, in our meticulous examination of the magnetic properties, we observed that ferromagnetic phases are exceptionally thermodynamically stable, demanding minimal energy input to maintain this state. This finding is significant in understanding the behavior of these materials under magnetic influences.Moving into the realm of magnetoelectronic, our analysis of the electronic band profiles using the Generalized Gradient Approximation (GGA) and the modified Becke-Johnson method (mBJ) revealed something truly remarkable. Both compounds exhibit metallic behavior alongside substantial spin polarization potential, hinting at exciting possibilities for their application in spintronic devices. Moreover, our scrutiny of the elastic properties confirmed the mechanical stability of these compounds, while the thermophysical analysis underscored their robustness in thermodynamic behaviors. These findings collectively point towards a promising future for these materials, indicating their immense potential for deployment in solid-state devices. Particularly, their impressive thermoelectric attributes, as unveiled by the BoltzTraP code, showcase remarkable Seebeck coefficients and electrical conductivities, emphasizing their strength in thermoelectrics.

Synthesis of electronegative S-filled and Sn–Te double substituted skutterudite compounds by HPHT and its thermoelectric properties

Electronegative S-filled skutterudite compounds have attracted considerable attention due to scattering of low-frequency phonons (35–50[Formula: see text]cm[Formula: see text]), but there are few reports on S-filled double-substituted skutterudite. In this work, a series of S-filled Te-Sn double-substituted skutterudite compounds were synthesized using high pressure and high temperature (HPHT) method. The phase composition, microstructure, and thermoelectric properties of SxCo4Sb[Formula: see text]Te[Formula: see text]Sn[Formula: see text] ([Formula: see text], 0.05, 0.10, 0.20) samples were systematically determined. The results show that the introduction of S increases the substitution limit of Te in the Sb site. Under the combined effect of the sample synthesis pressure and S filling, the nucleation density of the sample grains increases and the grain size decreases. At the same time, there are numerous special microstructures in the samples synthesized in a high-pressure environment. Thermoelectric performance studies show that a small amount of S filling optimizes the Seebeck coefficient of the sample and increases the power factor (PF). With an increase of the amount of S introduced, the thermal conductivity of the samples decreases significantly. Therefore, the maximum zT value of an S[Formula: see text]Co4Sb[Formula: see text]Te[Formula: see text]Sn[Formula: see text] sample synthesized at 2.5[Formula: see text]GPa pressure is 0.17 at room temperature. The maximum zT value of the sample is 1.26 at 773[Formula: see text]K.

Significant changes in thermoelectric properties of unfilled skutterudite compounds MSb3 (M = Co and Rh) by self-insertion reaction

We report thermoelectric properties of high-pressure phases SbxM4Sb12-x (M = Co and Rh) prepared by a self-insertion reaction from binary skutterudite compounds MSb3 under high pressure and high temperature. Electrical resistivity, Seebeck coefficient, and thermal conductivity were measured in the temperature range of 2–300 K. The lattice thermal conductivities of SbxM4Sb12-x showed a significant reduction. The minimum value is 1.32Wm−1K−1 (77% reduction compare to RhSb3) at 300 K for SbxRh4Sb12-x. The value is close to that of a triple filled skutterudite (Ba,La,Yb)xCo4Sb12 and is the smallest among the RhSb3 based single filled skutterudite.

Investigation of the Effect of Double-Filler Atoms on the Thermoelectric Properties of Ce-YbCo4Sb12.

Skutterudite compounds have been studied as potential thermoelectric materials due to their high thermoelectric efficiency, which makes them attractive candidates for applications in thermoelectric power generation. In this study, the effects of double-filling on the thermoelectric properties of the CexYb0.2-xCo4Sb12 skutterudite material system were investigated through the process of melt spinning and spark plasma sintering (SPS). By replacing Yb with Ce, the carrier concentration was compensated for by the extra electron from Ce donors, leading to optimized electrical conductivity, Seebeck coefficient, and power factor of the CexYb0.2-xCo4Sb12 system. However, at high temperatures, the power factor showed a downturn due to bipolar conduction in the intrinsic conduction regime. The lattice thermal conductivity of the CexYb0.2-xCo4Sb12 skutterudite system was clearly suppressed in the range between 0.025 and 0.1 for Ce content, due to the introduction of the dual phonon scattering center from Ce and Yb fillers. The highest ZT value of 1.15 at 750 K was achieved for the Ce0.05Yb0.15Co4Sb12 sample. The thermoelectric properties could be further improved by controlling the secondary phase formation of CoSb2 in this double-filled skutterudite system.

Superconducting Gap Structure of Filled Skutterudite LaOs4As12 Compound through μSR Investigations

Filled skutterudite compounds have gained attention recently as an innovative platforms for studying intriguing low-temperature superconducting properties. Regarding the symmetry of the superconducting gap, contradicting findings from several experiments have been made for LaRu4As12 and its isoelectronic counterpart, LaOs4As12. In this vein, we report comprehensive bulk and microscopic results on LaOs4As12 utilizing specific heat analysis and muon-spin rotation/relaxation (μSR) measurements. Bulk superconductivity with TC = 3.2 K was confirmed by heat capacity. The superconducting ground state of the filled-skutterudite LaOs4As12 compound is found to have two key characteristics: superfluid density exhibits saturation type behavior at low temperature, which points to a fully gapped superconductivity with gap value of 2Δ/kBTC = 3.26; additionally, the superconducting state does not show any sign of spontaneous magnetic field, supporting the preservation of time-reversal symmetry. These results open the door for the development of La-based skutterudites as special probes for examining the interplay of single- and multiband superconductivity in classical electron–phonon systems.

High-pressure and high-temperature synthesis of stable SxCo3.6Ni0.4Sb12 skutterudite compounds

Compared to Te, Ni is found in abundance in the earth's crust. At the same time, the mechanical properties of Ni atom-substituted skutterudite are significantly improved. In this study, a series of S-filled Ni-substituted skutterudite compounds were synthesized by a high-pressure and high-temperature (HPHT) method in the synthesis pressure range of 1.0–3.0 GPa. The phase composition, microscopic morphology, and electrothermal transmission properties of the SxCo3.6Ni0.4Sb12 (x = 0, 0.05, 0.10, 0.20) samples were systematically characterized. Phase composition analysis showed that the introduction of S atoms into the intrinsic pores of skutterudite can improve the solid solution limit of Ni atoms in the Co sites of skutterudite. The filling limit of S increased with the synthetic pressure. Moreover, microscopic morphology analysis revealed that the filling of S atoms inhibited the growth of grains. A large number of lattice fringes in different directions were found in the sample, containing abundant microstructures such as lattice distortions and dislocation defects. Compared with the synthesized samples, S0.05Co3.6Ni0.4Sb12 synthesized at 1.0 GPa had a maximum room temperature power factor of 7.98 × 10−4 Wm−1K−2. The electrical properties of S0.05Co3.6Ni0.4Sb12 samples stored for 6 months without any protective measures were tested at room temperature. No obvious changes in performance were observed, which proved that the HPHT method can synthesize stable samples. After several thermal cycles, the electrical properties of the S0.05Co3.6Ni0.4Sb12 sample was tested for variable temperature, and it was found that the sample still had good stability. How the substitution of S atoms with Ni atoms reduces the lattice thermal conductivity can be explained by fitting the Callaway model. The S0.05Co3.6Ni0.4Sb12 sample synthesized at 1.0 GPa had a maximum zT value of 0.46 at the test temperature of 773 K, which decreased to 0.43 after multiple thermal cycles at the same temperature.

Interfacial thermoelectric and mechanical properties of indigenously prepared Ni–Cr–Cu/Co4Sb12 skutterudite thermoelectric joints

Thermoelectric and mechanical properties of indigenously prepared Ni–Cr–Cu/Co4Sb12 skutterudite thermoelectric joints are reported. Co4Sb12 based skutterudite compounds are highly enticing mid-temperature thermoelectric materials for waste-heat harvesting. Ni–Cr–Cu electrode powder is prepared by ball milling, and a one-step sintering route is adopted to fabricate the Ni–Cr–Cu electrode/n-type Dy0.4Co3.2Ni0.8Sb12 thermoelectric joints. The processed Ni–Cr–Cu/skutterudite joint interface is continuous without having any crack and has low contact resistance (<12 μΩ cm2). The contact resistance at the interface of the joints decreases to 7 μΩ cm2 under thermal ageing at 823 K for 15 days in a vacuum. The mechanical properties of the joints are not degraded even after ageing at 823 K for 15 days. The theoretical lifetime of the skutterudite device using the Ni–Cr–Cu/Dy0.4Co3.2 Ni0.8Sb12 joints is calculated to be 11 years while maintaining the hot side temperature of the device at 773 K. Our results demonstrate that indigenously prepared Ni–Cr–Cu/Co4Sb12 thermoelectric joints can be effectively used for skutterudite module fabrication.

HPHT synthesis and enhanced thermoelectric transport properties of double-doped Co4Sb11TexSn1-x skutterudites

The high-pressure and high-temperature (HPHT) technique was employed to prepare skutterudite-based polycrystalline materials Co4Sb11TexSn1-x (x = 0.5, 0.6, 0.7). The thermoelectric properties, as well as electrical transport properties near room temperature, were researched systematically. The results indicated that the Sn and Te co-doped specimens yielded an impressive depression in lattice thermal conductivity (κL) based on the point-defect scattering. The κL exhibited a positive Te doping level dependence. Therefore, a minimum lattice thermal conductivity was 1.41 Wm−1K−1 for Co4Sb11Te0.7Sn0.3. Consequently, the thermoelectric dimensionless figure of merit, ZT, was remarkably enhanced from 300 to 725 K. The maximum ZT was 1.13 for Co4Sb11Te0.7Sn0.3 at 711 K, which is better than that of pure Co4Sb12. This value is nearly improved one order of magnitude and rivals the state-of-the-art single-filled n-type skutterudite compounds. Compared to the traditional synthesized method, high pressure and high-temperature techniques can fundamentally reduce the reaction duration from several days to less than an hour and provide a different route for the synthesis of thermoelectric materials.

Multiple-Filling-Induced Full-Spectrum Phonon Scattering and Band Convergence Leading to High-Performance n-Type Skutterudites.

Filling guest atoms into the nanovoids of skutterudite compounds provides effective scattering for low-frequency phonons to reduce the lattice thermal conductivity. However, it is still difficult to simultaneously realize the full-spectrum phonon scattering and band engineering in the n-type skutterudites with higher thermoelectric performance. Here, we reveal that the combination of five types of element atoms in the lattice nanovoids brings about dense dislocations, abundant precipitated nanoparticles, and electronic band convergence in the n-type skutterudites. The Seebeck coefficient shows an increase with little deterioration on the carrier mobility due to the enhanced density of states near the Fermi level, leading to a 11% enhancement in the power factor at 823 K. The lattice thermal conductivity is significantly reduced to approach the glass limit due to the full-spectrum phonon scattering. As a result, a peak ZT value of about 1.7 at 823 K and an average ZT value of about 1.2 from 323 to 823 K are obtained. High thermoelectric performance combined with the structural optimization enables the simulated maximum energy conversion efficiency of the skutterudite module to reach up to 15.0%. Our finding opens a new dimension for doping atoms to achieve simultaneous optimization of electrical and thermal properties in polynary thermoelectric materials.

Synthesis and thermoelectric performance of Ni0.3Co3.7Sb12 skutterudite filled with electronegative guest Se

Electronegative guests can be induced to fill the voids of skutterudite by doping electron donors in the framework of skutterudites. This method has been considered a promising method to improve thermoelectric properties. In this study, SeyNi0.3Co3.7Sb12 (y = 0, 0.025, 0.1, 0.125, 0.15) skutterudite compounds were prepared using a melt-quenching-annealing synthesis route and spark plasma sintering technology. The phase constituents, microstructure, thermoelectric properties, and thermal transport properties were investigated. Experimental results suggest that the charge compensation between Ni doping and Se filling has a positive effect on the formation of thermodynamically stable SeyNi0.3Co3.7Sb12 alloys. The existence of Se fillers in the voids reduces the lattice thermal conductivity. As the filling fraction of Se increases, the number of holes increases while the electron concentration decreases. The figure of merit (zT) of Se0.15Ni0.3Co3.7Sb12 reaches a maximum of 0.81 at 823 K.

Lattice dynamics of YbxCo4Sb12 skutterudite by machine-learning interatomic potentials: Effect of filler concentration and disorder

Lattice dynamics determines a number of important properties of solids. While computational methods with predictive power have been developed in this area, the task is still difficult for the complex compounds. We present a method for automatic on-the-fly generation of multicomponent interatomic potentials. The method is based on active learning, which ensures effective extrapolation to new atomic environments. The accuracy is then demonstrated on the example of the Yb-filled skutterudite compound ${\mathrm{Yb}}_{x}{\mathrm{Co}}_{4}{\mathrm{Sb}}_{12}$, which is a family of the promising thermoelectric materials. Atomic displacements, vibrational spectrum, and lattice thermal conductivity were obtained and the effect of the Yb filling and ordering was studied as 700 K. The potential allowed us to reproduce fine features of the vibrational spectrum, as well as the reduction of the lattice thermal conductivity with filling. We found only a small effect of the disorder on the vibrational spectrum and the thermal conductivity.

Elastic, electronic, vibrational and optical properties of filled skutterudite compound SrRu4As12: Insights from DFT-based computer simulation

Structural, elastic, electronic, and optical properties of filled skutterudite compound SrRu4As12 have been studied by using density functional theory with CASTEP code for the first time. The optimized structural parameters show good agreement with available experimental and theoretical values. The calculated single elastic constants are positive and agreed with the well-known Born stability criteria that indicate the mechanical stability of this compound. The phonon dispersion curve exhibit dynamical stability. The studied compound is found to be semi-metallic, anisotropic and brittle in nature. The highest bond population exists in As–As, indicating the highly covalent nature of SrRu4As12. Peierls stress value indicates that the dislocation moves very easily for filled skutterudite compounds. The calculated Debye temperature, minimum thermal conductivity, and melting temperature reveal the possibility to be used as a TBC material. High reflectivity also suggests that SrRu4As12 could be a promising protective coating material against solar heating. The Fermi surface, charge density, atomic, and bond population have also been calculated to analyze the bonding nature.

Efficiently synthesized n-type CoSb3 thermoelectric alloys under TGZM effect

Skutterudite compounds, the structure of "phonon glass electron crystal" (PGEC), possess excellent thermoelectric properties. Here, temperature gradient zone melting combined with hot pressing technique (TGZM-HP) was employed to synthesize n-type skutterudite CexNi1.5Co2.5Sb12 thermoelectric material. By doping element Ce, the carrier concentration of the alloy was optimized efficiently and the total thermal conductivity declined. For the TGZM-HP Ce0.6Ni1.5Co2.5Sb12 alloy, the power factor PF reaches to 1350 μW/(mK2), and the lattice thermal conductivity is dropped to 1.62 Wm−1K1 at 850 K, corresponding to an improved figure of merit ZT of 0.45. Importantly, compared with the traditional synthesis methods, this technique can precisely control the formation of thermometric phase and the preparation time is reduced remarkably.

Ferrimagnetism in EuFe4As12 revealed by Eu153 NMR and As75 NQR measurements

Filled skutterudite compound EuFe$_4$As$_{12}$ shows the highest magnetic ordering temperature of $T_{\rm C}$ = 154 K among Eu-based skutterudite compounds, but its magnetic ground state has not been determined yet. Here, we performed $^{153}$Eu nuclear magnetic resonance (NMR) and $^{75}$As nuclear quadrupole resonance (NQR) measurements on EuFe$_4$As$_{12}$ to reveal its magnetic ground state as well as the physical properties from a microscopic point of view. From the temperature and magnetic field dependence of $^{153}$Eu NMR spectrum in the magnetically ordered state, we found that the Eu ions are in Eu$^{2+}$ state with a nearly 7 $\mu_{\rm B}$ corresponding to $S$ = 7/2 spins. Combined with the magnetization measurements which show the reduced saturation moments of 4.5 $\mu_{\rm B}$/f.u., we determined the ground magnetic structure in EuFe$_4$As$_{12}$ to be ferrimagnetic where the Eu$^{2+}$ 4$f$ and the Fe 3$d$ ordered moments are ferromagnetically aligned in each sublattice but the moments between the sublattices are antiferromagnetically aligned. We also found the local distortion at the Eu site from the cubic symmetry in the magnetically ordered state. The relationship between the rattling motion of Eu atoms and the local symmetry of the Eu ions is discussed. From the $^{75}$As NQR nuclear spin-lattice relaxation time measurements as well as $^{153}$Eu NMR measurements, we found that the 4$f$ electrons of the Eu ions are well described by the local moment picture in both the magnetic and paramagnetic metallic states.

The effect of spin–orbit interaction on superconductivity in the filled skutterudites MPt4Ge12(M=Ba, Sr and Th)

ABSTRACT Ab initio pseudopotential calculations have been conducted for the superconducting filled skutterudite compounds BaPtGe, SrPtGe, and ThPtGe in order to explore the effect of spin–orbit interaction(SOI) by using the planewave pseudopotential method and the density functional theory. The electronic structure calculations suggest that the density of states at the Fermi level is dominated by Ge atom's p states, with the guest atoms (Ba, Sr, or Th) making very little or no contribution. However, when the SOI is included, the phonon frequencies of BaPtGe and SrPtGe are hardened, which in turn decreases the electron–phonon interaction. By integrating the Eliashberg spectral function F(ω) with SOI included, the average electron–phonon coupling parameters are found to be 0.74 for BaPtGe, 0.79 for SrPtGe, and 0.69 for ThPtGe. Using a reasonable value of = 0.10 for the effective Coulomb repulsion parameter, the superconducting critical temperature is found to be 5.36 K for BaPtGe, 5.43 K for SrPtGe, and 4.45 K for ThPtGe with SOI. These values are in excellent accordance with their reported experimental values of 5.35 K, 5.4 K and 4.62 K.

Theoretical Prediction of the Structural, Elastic, Electronic and Thermodynamic Properties of Binary CoP3 and Ternary FeCoP3 Skutterudites Materials

The structural, elastic, electronic and thermodynamic properties of skutterudite binary compound CoP3 and the ternary alloy FeCoP3 were investigated by using the full-potential linearized augmented plane-wave plus local orbitals method within the approximation GGA-PBEsol functional. The computed lattice constants, bulk moduli and the pressure derivative of the bulk moduli at the equilibrium are in good agreement with the published experimental data. The brittleness and ductility of these materials were studied by the analysis of the elastic constants and other mechanical parameters, where we have found that both CoP3 and FeCoP3 are ductile materials. The electronic band structure calculation, using the modified Becke-Johnson potential (TB-mBJ), shows that the skutterudite binary compound CoP3 at equilibrium, present a narrow indirect bandgap of 0.524[Formula: see text]eV where the ternary alloy FeCoP3 is a metal behavior. Finally, we investigated the impact of pressure [Formula: see text] and temperature [Formula: see text] on the lattice parameters, heat capacities [Formula: see text], Debye temperatures [Formula: see text] and the entropies [Formula: see text] using the quasi-harmonic Debye model.

Low-temperature thermoelectric properties of p-type and n-type filled skutterudite compounds Smy(Fe1−xNix)4Sb12 prepared under high pressure

Filled skutterudite compounds Smy(Fe1−xNix)4Sb12 (nominal composition 0 ≤ x ≤ 0.56, 0.1 ≤ y ≤ 1.2) were synthesized under high pressure using a cubic anvil press. The samples were characterized by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectrometry and electron probe microanalyzer. Thermoelectric properties of Smy(Fe1−xNix)4Sb12 were investigated in the temperature range of 2–300 K. The Seebeck coefficient of samples exhibits the feature of p-type and n-type conductors depending on Sm-filling ratio and Fe/Ni content. The highest dimensionless figure of merit ZT value of 0.167 is achieved for nominal composition Sm0.2(Fe0.6Ni0.4)4Sb12 at room temperature.

Enhancing NASA's Multi-Mission Radioisotope Thermoelectric Generator Using Highly Efficient Thermoelectric Materials

This project proposal aims to enhance NASA’s Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) by identifying and analyzing new material technologies that have been researched for their excellent thermoelectric properties at higher temperatures. By choosing the most efficient thermoelectric material available, the MMRTG’s energy conversion efficiency will be greatly improved as thermoelectric generator efficiencies are largely determined by the properties of the materials within the thermocouple devices used to convert the heat into energy. A project that focuses on enhancing the MMRTG is imperative for the future of space exploration as there is global shortage of plutonium fuel production, limiting future missions to available supplies. A more efficient generator will minimize the use of this fuel while maximizing power output, allowing for increased mission capabilities and better conservation of the scarce plutonium fuel. In this report, lanthanum telluride, Yb14MnSb14, and a multiple-filled skutterudite (SKD) compound are analyzed for their excellent thermoelectric performance. The multiple filled SKD compound is chosen as the ideal material to enhance the MMRTG based on the low cost and low risks associated with the material while producing a nearly identical efficiency relative to the other candidates. Keywords: eMMRTG, MMRTG, thermoelectric materials, thermoelectric generator, efficiency

Crystal growth, low-temperature specific heat, and electronic structure of the filled skutterudite compound ThOs4As12

ABSTRACTSingle crystals of the filled skutterudite compound ThOsAs were grown by a Cd:As flux method. Low-temperature specific-heat measurement reveals a very small Sommerfeld coefficient of the electronic term mJ/molK, indicative of a semiconducting or semimetallic character of ThOsAs. A low electronic density of states at the Fermi level is consistent with anticipations based on the Zintl concept for the filled skutterudites as well as with our results of band structure calculations. Investigations of a nonmagnetic material ThOsAs can be relevant to unmask puzzling strong electron correlations in the putative topological Kondo insulator CeOsAs.