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Thermoelectric cooling materials based on Bi2Te3 have a long history of unsurpassed performance near room temperature. Recently, research into price‐competitive Mg3(Bi, Sb)2‐based materials are focused on replacing traditional cooling materials. Here, the thermoelectric properties of Mg3.2Bi1.998−xSbxTe0.002Cu0.005 (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) polycrystalline compounds are investigated. In all temperature regions, electrical resistivity and Seebeck coefficient are increased with Sb concentration. The electronic transport properties of Sb‐alloyed compounds are maximized by synergistically combined band engineering approaches such as band structure change caused by lattice strain, increased electronic density of states, and chemical potential shift, leading to exceptionally high‐power factor values of over 3.0 mW m−1 K−2 at room temperature. Furthermore, with increasing Sb content, thermal conductivity values are systematically reduced due to the promotion of alloy scattering of phonons and suppression of the bipolar contribution. Consequently, these multiple approaches significantly enhance thermoelectric performance, resulting in an enhancement of thermoelectric figure‐of‐merit zT above 1.1 at 348–423 K. Additionally, a zTavg of 1.1 is recorded at 300–450 K, making it an unrivaled value among the reported n‐type Mg3Bi2‐based thermoelectric materials. Overall, this work demonstrates that Mg3Bi2‐based materials are more promising for thermoelectric cooling applications compared to Bi2Te3‐based materials. [ABSTRACT FROM AUTHOR]

Oxides are of interest for thermoelectrics due to their high thermal stability, chemical inertness, low cost, and eco‐friendly constituting elements. Here, adopting a unique synthesis route via chemical co‐precipitation at strongly alkaline conditions, one of the highest thermoelectric performances for ZnO ceramics (PFmax=$PF_{\text{max}} =$ 21.5 µW cm−1 K−2 and zTmax=$zT_{\text{max}} =$ 0.5 at 1100 K in Zn0.96Al0.04O${\rm Zn}_{0.96} {\rm Al}_{0.04}{\rm O}$) is achieved. These results are linked to a distinct modification of the electronic structure: charge carriers become trapped at the edge of the conduction band due to Anderson localization, evidenced by an anomalously low carrier mobility, and characteristic temperature and doping dependencies of charge transport. The bi‐dimensional optimization of doping and carrier localization enable a simultaneous improvement of the Seebeck coefficient and electrical conductivity, opening a novel pathway to advance ZnO thermoelectrics. [ABSTRACT FROM AUTHOR]

Higher manganese silicides (denoted as MnSiγ ) are a prominent class of intermetallic compound for thermoelectric applications that crystallizes into a Nowotny Chimney Ladder (NCL) phase and constitutes a higher concentration of silicon with odd stoichiometry, typically represented by an irrational number. In this work, the genesis of Si odd stoichiometry and secondary phase relations in silicon-rich and silicon-deficient MnSix is presented to clarify the significance of labile (i.e., easily alterable) Si-subsystem in inheriting the modulated lattice structure with characteristic anharmonicity. The transport properties show an interrelation to the presence of a secondary phase, which is driven by the odd stoichiometry, where the thermoelectric figure of merit (zT) is found to be optimal for MnSi1.74. The structural characterization of rapidly solidified melt-spun ribbons and spark plasma sintered bulk specimens reveal a characteristic presence of MnSi and Si as secondary phases in Si-deficient (x ≈ 1.5) and Si-excess (x ≈ 2) compositions of nominal MnSix, respectively, that coexists with the major MnSiγ based NCL phase. This study provides the fundamental basis of phase evolution and the relevance of odd stoichiometry in silicon-rich manganese silicides which exhibit fascinating phonon dynamics in optimal MnSi1.74 stoichiometry. [ABSTRACT FROM AUTHOR]

In the realm of optoelectronic applications, the incorporation of a metal interlayer between layers of a topological material holds significant potential. The interlayer introduces benefits such as improved charge transfer efficiency, tunable band alignment, plasmonics effect, and enhanced light‐matter interactions, paving the way for more efficient and versatile optoelectronic devices. This work explores the incorporation of gold between Bi2Se3, resulting in an enhancement in the response time of photoresponse of interlayered systems (Bi2Se3‐Au‐Bi2Se3). The introduction of a gold interlayer between Bi2Se3 significantly influences the overlayer structure, crystallinity, crystallite size, and even phonon behavior. Moreover, the responsivity of the interlayered device at a bias (2 V) is found to have high responsivity with fast response and decay time (τr = 0.1 ms, and τd = 24 ms of interlayered systems) as compared to intrinsic Bi2Se3(τr = 0.6 ms, and τd = 28 ms). This change is attributed to the bandgap alteration of the Bi2Se3/Au interface, which is monitored through transient spectroscopy performed at different electric biases. This study suggests that incorporating a gold interlayer holds potential benefits for various optoelectronic applications. [ABSTRACT FROM AUTHOR]

Heterostructures of two‐dimensional materials realise novel and enhanced physical phenomena, making them attractive research targets. Compared to inorganic materials, coordination nanosheets have virtually infinite combinations, leading to tunability of physical properties and are promising candidates for heterostructure fabrication. Although stacking of coordination materials into vertical heterostructures is widely reported, reports of lateral coordination material heterostructures are few. Here we show the successful fabrication of a seamless lateral heterojunction showing diode behaviour, by sequential and spatially limited immersion of a new metalladithiolene coordination nanosheet, Zn3BHT, into aqueous Cu(II) and Fe(II) solutions. Upon immersion, the Zn centres in insulating Zn3BHT are replaced by Cu or Fe ions, resulting in conductivity. The transmetallation is spatially confined, occurring only within the immersed area. We anticipate that our results will be a starting point towards exploring transmetallation of various two‐dimensional materials to produce lateral heterojunctions, by providing a new and facile synthetic route. [ABSTRACT FROM AUTHOR]

Developing thermoelectric (TE) performance is impeded by the compromise of TE parameters, resulting in inadequate conversion efficiency of heat to electricity. Herein, this work reports that Mo is a particularly effective additive in Mg3Sb2‐based alloys with significantly improved electronic transport via grain‐boundary engineering and band‐structure regulation synergy. In addition, phonon transport is simultaneously suppressed by employing multiple effects, lattice imperfection scattering, reduced phonon group velocity, and enhanced atomic disorder, leading to a minimum κlat = 0.52 W m−1 K−1 at 723 K. As a result, an outstanding ZT peak of ≈1.84 at 723 K and ZTav = 1.34 within 323–723 K are achieved in Mg3Sb2‐based alloys, and the corresponding fabricated single‐leg TE module shows an exceptionally high conversion efficiency of ≈12% under a hot‐side temperature of 450 °C. These results demonstrate the great potential for advancing mid‐temperature heat harvesting in Mg3Sb2‐based materials. [ABSTRACT FROM AUTHOR]

The structural, electronic, thermal and lattice thermal transport properties of the three hypothetical quaternary Heusler alloys FeRuTiX (X=Si, Ge, Sn) were investigated with the aid of first‐principles calculations. All compounds were found to be semiconducting with a small indirect band gap. Flat bands near the conduction band edge and degenerate multi‐bands near the valance band edge suggest that these systems should exhibit both large Seebeck coefficients and good electrical conductivity. The analysis of the calculated vibrational spectra showed that the three compounds are thermodynamically stable. The computed lattice thermal conductivity indicates that among the three compounds that of FeRuTiSn is rather low at high temperature. Indeed, a low lattice thermal conductivity (∼3.5 Wm−1 K−1 at 1000 K) together with a small electronic band gap (0.51 eV) with an appropriate electronic structure (disperse and flat bands) render FeRuTiSn a promising candidate as a high‐temperature thermoelectric material. [ABSTRACT FROM AUTHOR]

The pillars of Green Chemistry necessitate the development of new chemical methodologies and processes that can benefit chemical synthesis in terms of energy efficiency, conservation of resources, product selectivity, operational simplicity and, crucially, health, safety, and environmental impact. Implementation of green principles whenever possible can spur the growth of benign scientific technologies by considering environmental, economical, and societal sustainability in parallel. These principles seem especially important in the context of the manufacture of materials for sustainable energy and environmental applications. In this review, the production of energy conversion materials is taken as an exemplar, by examining the recent growth in the energy‐efficient synthesis of thermoelectric nanomaterials for use in devices for thermal energy harvesting. Specifically, "soft chemistry" techniques such as solution‐based, solvothermal, microwave‐assisted, and mechanochemical (ball‐milling) methods as viable and sustainable alternatives to processes performed at high temperature and/or pressure are focused. How some of these new approaches are also considered to thermoelectric materials fabrication can influence the properties and performance of the nanomaterials so‐produced and the prospects of developing such techniques further. [ABSTRACT FROM AUTHOR]

BiSbTe‐based nanocomposites hybridized with ceramic nanoparticles have recently revealed their higher efficiency as thermoelectric materials for near room‐temperature applications, as compared to the traditional BiTe‐SbTe alloys. Herein, the incorporation of ultra‐small Bi nanoprecipitates into the microstructure of a Bi0.5Sb1.5Te3/Sb2O3 nanocomposite and the consequential effects on the thermal and electrical transport properties of this three‐phase hybrid system is reported. Electron microscopy characterization and systematic analysis of the thermoelectric properties of Bi0.5Sb1.5Te3/Sb2O3/Bi nanoprecipitate samples suggest that the minute Bi nanoprecipitates increase the charge carrier concentration of the nanocomposites, act as effective scattering sites throughout the microstructure, and shift the maximum Seebeck coefficient values to higher temperatures. [ABSTRACT FROM AUTHOR]

We investigated the effects on thermoelectric properties of Cu doping in Fe2‐xCuxVAl at Fe site of full‐Heusler type compound. It is found that the Cu doping for Fe sites causes a significant increase in the absolute value of Seebeck coefficient |S| and a decrease in thermal conductivity. The Seebeck coefficient (S)=‐148μV/K and the Power factor (PF)=4.0 mWK−2m−1 have been observed for Fe1.9Cu0.1VAl (x=0.1) at 300 K. To further improve it, we fixed the Cu doping level at x=0.1 in Fe2‐xCuxVAl and co‐doped the material with Si at Al site, namely, Fe1.9Cu0.1VAl1‐ySiy. The thermoelectric properties have been improved by Si doping to a certain limit. We observed a decrease in electrical resistivity and lattice thermal conductivity by Si doping for Al. The maximum power factor of 4.5 mWK−2m−1 has been achieved for Fe1.9Cu0.1Al0.9Si0.1 at 350 K. More precisely, the thermoelectric performance has been improved with co‐doping of Cu for Fe sites and Si for Al sites. The largest ZT value is 0.13 for Fe1.9Cu0.1VAl1‐ySiy (y=0.15). Magnetic susceptibility suggests that all the measured compounds are showing paramagnetic behavior. The magnetic character is the most pronounced in Fe1.9Cu0.1VAl among the materials investigated, pointing to a possible correlation between the magnetic character due to electronic correlation and the larger Seebeck coefficient in this sample. [ABSTRACT FROM AUTHOR]

GeTe is a promising candidate for the fabrication of high‐temperature segments for p‐type thermoelectric (TE) legs. The main restriction for the widespread use of this material in TE devices is high carrier concentration (up to ∼ 1021 cm−3), which causes the low Seebeck coefficient and high electronic component of thermal conductivity. In this work, the band structure diagram and phase equilibria data have been effectively used to attune the carrier concentration and to obtain the high TE performance. The Ge1−xBixTe (x = 0.04) material prepared by the Spark plasma sintering (SPS) technique demonstrates a high power factor accompanied by moderate thermal conductivity. As a result, a significantly higher dimensionless TE figure of merit ZT = 2.0 has been obtained at ∼ 800 K. Moreover, we are the first to propose that application of the developed Ge1−xBixTe (x = 0.04) material in the TE unicouple should be accompanied by SnTe and CoGe2 transition layers. Only such a unique solution for the TE unicouple makes it possible to prevent the negative effects of high contact resistance and chemical diffusion between the segments at high temperatures. [ABSTRACT FROM AUTHOR]

SiGe‐based thermoelectric (TE) materials are well‐known for high‐temperature utilization, but rarely relevant in the low temperature region. Here a Ge quantum dots (QDs) and Sn precipitation SiGeSn hybrid film are constructed via ultrafast high temperature annealing (UHA) of a treated P‐ion implantation SiGeSn film on Si/SiO2 substrate. Combining the modulation doping effect dominated by Sn precipitates and the energy filtering effect caused by Ge QDs, the optimized SiGe films achieve a giant power factor as high as 91 µW cm−1 K−2 @300 K, room temperature, while maintaining low thermal conductivity. This strategy on film construction provides a novel insight for TE materials with striking performance. [ABSTRACT FROM AUTHOR]

This document is an editorial introducing a special collection in the journal ChemNanoMat on the topic of thermoelectrics and energy-harvesting materials. The collection covers a wide range of aspects related to thermoelectrics, including materials, devices, and processing techniques. The articles discuss various strategies for improving the performance of thermoelectric materials, such as defect engineering and alloying, as well as the use of non-toxic and sustainable materials. The collection also explores device-level considerations, such as contact optimization and mechanical properties. The guest editors of the collection are Takao Mori, Ady Suwardi, and Sima Aminorroaya, who are experts in the field of materials science and engineering. [Extracted from the article]

Most of the best known SnTe‐based materials exhibit an attractive thermoelectric figure of merit (zT) only at the high‐temperature regime, but their performance at the low‐mid temperature ranges is quite uninspiring, and this discordance necessitates a large temperature gradient (∆T ≥ 550 K) to effectuate a reasonable efficiency, η. Here, the transition elements, Ti and Zr, that have not been used in the past are tried as dopants for SnTe and an enhanced device/average zT and/or η are reported with a lower ∆T ≈ 400 K and without the requisite for a stupendous peak/maximum zT. This notable performance emanates from—i) improved weighted mobility by optimally balancing between effective mass, carrier concentration, and mobility, ii) coupling of charge carriers with magnetic entropy, and the paramount factor being the iii) weakening of the chemical bonds (lattice softening). The thermal damping caused by lattice softening affects the phonon group velocity and the elastic properties, and the resultant increase in the degree of anharmonicity and the high density of internal strain‐fields, along with the phonon scattering effects, play an active role in tuning the overall thermoelectric performance. This work also excavates/opens up the discussion of applying the Heikes' equation to qualitatively compare the trend of charge carriers for a given thermoelectric material system. [ABSTRACT FROM AUTHOR]

A unified structure model in (3 + 1)‐dimensional superspace proved suitable for identification of a homologous phase (Ga1−αAlα)2O3(ZnO)m by the profile fitting of powder X‐ray diffraction intensities for thermoelectric composite materials in the pseudoternary system ZnO–Al2O3–Ga2O3. A homologous compound of the phase parameter m ≃ 37 was found to coexist with (Al,Ga)‐doped ZnO in samples sintered at 1723 K in air. The thermoelectric properties of the composite materials were closely related to the phase fractions. The higher the phase fraction of (Al,Ga)‐doped ZnO with the wurtzite structure, the higher the electrical conductivity. On the other hand, the homologous compound with the long‐period structure was effective in lowering the thermal conductivity of the materials. [ABSTRACT FROM AUTHOR]

Modification of crystal symmetry induced by chemical doping or alloying is well known to optimize the charge carrier transport properties in thermoelectric materials. Historically, the altered defect chemistry of the targeted materials, however, has long been neglected or underestimated, which may, in turn, favorably or adversely affect the thermoelectric properties. Herein, using a case study of thermoelectric GeTe, first, the hidden role of rhombohedral distortion degree on the Ge‐vacancy formation energy is theoretically unraveled, and it is experimentally found that Sc and Bi codoping realize a superior thermoelectric performance. Density functional theory calculations demonstrate that the distorted rhombohedral lattice closer to cubic would unexpectedly induce the significantly decreased formation energy of Ge vacancies, resulting in the spontaneous formation of higher‐concentration Ge vacancies. Sc doping is found to be the most effective dopant to reduce the carrier concentration without obviously affecting the rhombohedral distortion degree, leading to the realization of a record‐high power factor. Benefiting from the suppressed thermal conductivity by further Bi doping, an ultrahigh average ZT ≈1.2 from 300 to 723 K is achieved. These discoveries provide new insights into the relationship between crystal symmetry and defect chemistry, and also promote GeTe materials for future thermoelectric applications. [ABSTRACT FROM AUTHOR]

In an article published in Angewandte Chemie, Hiroshi Nishihara et al. present a new method for creating lateral heterojunctions in two-dimensional materials. These heterojunctions have rectifying properties and can be fabricated by immersing a coordination nanosheet made from zinc ions and benzenehexathiol into iron and copper salt solutions. This research has implications for utilizing the attractive properties of two-dimensional materials more effectively. The authors of the article include Choon Meng Tan, Naoya Fukui, Kenji Takada, Hiroaki Maeda, Ekaterina Selezneva, Cédric Bourgès, Hiroyasu Masunaga, Sono Sasaki, Kazuhito Tsukagoshi, Takao Mori, Henning Sirringhaus, and Hiroshi Nishihara. [Extracted from the article]

In an article published in Angewandte Chemie International Edition, Hiroshi Nishihara et al. present a new method for creating lateral heterojunctions in two-dimensional materials. These heterojunctions have rectifying properties and are formed by immersing a coordination nanosheet made from zinc ions and benzenehexathiol into iron and copper salt solutions. This research has implications for utilizing the attractive properties of two-dimensional materials more effectively. The authors of the article include Choon Meng Tan, Naoya Fukui, Kenji Takada, Hiroaki Maeda, Ekaterina Selezneva, Cédric Bourgès, Hiroyasu Masunaga, Sono Sasaki, Kazuhito Tsukagoshi, Takao Mori, Henning Sirringhaus, and Hiroshi Nishihara. [Extracted from the article]

Abstract: Ideal materials for modern electronics packaging should be highly thermoconductive. This may be achieved through designing multifunctional polymer composites. Such composites may generally be achieved via effective embedment of functional inorganic fillers into desirable polymeric bodies. Herein, two types of high‐performance 3D h‐BN porous frameworks (3D‐BN), namely, h‐BN nanorod‐assembled networks and nanosheet‐interconnected frameworks, are successfully created via an in situ carbothermal reduction chemical vapor deposition substitution reaction using carbon‐based nanorod‐interconnected networks as templates. These 3D‐BN porous materials with densely interlinked frameworks, excellent mechanical robustness and integrity, highly isotropous and multiple heat transfer paths, enable reliable fabrications of diverse 3D‐BN/polymer porous composites. The composites exhibit combinatorial multifunctional properties, such as excellent mechanical strength, light weight, ultralow coefficient of thermal expansion, highly isotropic thermal conductivities (≈26–51 multiples of pristine polymers), relatively low dielectric constants and super‐low dielectric losses, and high resistance to softening at elevated temperatures. In addition, the regarded 3D‐BN frameworks are easily recycled from their polymer composites, and may be reliably reutilized for multifunctional reuse. Thus, these materials should be valuable for new‐era advanced electronic packaging and related applications. [ABSTRACT FROM AUTHOR]

Abstract: Boron carbide, the simple chemical combination of boron and carbon, is one of the best‐known binary ceramic materials. Despite that, a coherent description of its crystal structure and physical properties resembles one of the most challenging problems in materials science. By combining ab initio computational studies, precise crystal structure determination from diffraction experiments, and state‐of‐the‐art high‐resolution transmission electron microscopy imaging, this concerted investigation reveals hitherto unknown local structure modifications together with the known structural alterations. The mixture of different local atomic arrangements within the real crystal structure reduces the electron deficiency of the pristine structure CBC+B12, answering the question about electron precise character of boron carbide and introducing new electronic states within the band gap, which allow a better understanding of physical properties. [ABSTRACT FROM AUTHOR]

The phase and chemical compositions of the mineral chalcopyrite from the sulfide footwall vein in La Cantera (Zacatecas, Mexico) is examined by powder X-ray diffraction, energy dispersive X-ray spectroscopy, and chemical ICP-OES analyses. The influence of the detected impurities on the thermoelectric parameters (i.e. thermo-power, electrical and thermal conductivities) is discussed. Thermoelectric figure of merit, ZT, of the studied natural minerals is found to be of the same order of magnitude (ca. 10-3) as reported for CuFeS2 synthesized in the laboratory. [ABSTRACT FROM AUTHOR]

SUMMARY The conventional auxiliary power supply (APS) of a railway vehicle is directly connected to the catenary through the LC filter. Hence, the switching devices of the APS must have a high breakdown voltage to account for catenary voltage fluctuation. On the other hand, low-voltage switching devices have better characteristics that are desirable for low-loss and high-frequency operation. Therefore, a step-down converter is incorporated between the LC filter and inverter to adapt to catenary voltage fluctuations when using low-voltage switching devices. This paper proposes the series-parallel continuously regulated chopper as a novel step-down converter. First, the fundamental operation characteristics and output voltage control method of the proposed chopper are introduced. The simulation and experimental results for the fundamental characteristics are then described; the simulation and experimental values were almost the same as the theoretical values. The proposed chopper controls the output voltage at the expected value without dramatic fluctuation regardless of the input voltage fluctuation. In addition, a resonance damping control for a constant power load is proposed. The operational characteristics were considered under different potential distributions or load conditions. [ABSTRACT FROM AUTHOR]

The reduction of the diameter of Bi nanowires below 10 nm has been an important target because of the theoretical prediction with regard to significant enhancement in thermoelectric performance by size reduction. In this study, we have demonstrated the usefulness of mesoporous silica with tunable pore size as a template for the preparation of thin Bi nanowires with diameters below 10 nm. Bi was deposited within the templates through a liquid phase deposition using hexane and 1,1,3,3-tetramethyldisiloxane as a solvent and reducing agent, respectively. Bundles of thin Bi nanowires with non-crystalline frameworks were successfully obtained after the template removal. The diameter was precisely controlled between about 6 nm and 9 nm. The judicious choices of mesoporous silica and deposition conditions are critical for the successful preparation. The reliable formation of such thin Bi nanowires reported here opens up exciting new possibilities. [ABSTRACT FROM AUTHOR]

First, a large sample of Ni0.05Mo3Sb5.4Te1.6 was prepared by heating the elements in the stoichiometric ratio. β-SiC nanoparticles were added in volume fractions, f, of 0.01, 0.02, and 0.034 to three different portions of the material, and a portion without SiC nanoparticles was retained as a reference. All four samples were subjected to consolidation by hot-pressing. Furthermore, Al2O3 nanoparticles were added in volume fractions of f = 0.01, 0.0216, and 0.0325 to three other portions, again retaining a fourth protion as reference. These four samples were consolidated by spark-plasma sintering. The thermoelectric transport properties of these composites were characterized from 325 to 740 K. For the sample with 0.01 volume fraction of SiC, there was an enhancement in figure of merit by 18 % compared with the reference sample, mainly due to an 18 % reduced thermal conductivity. The 9 % reduction in thermal conductivity of the sample with 0.01 volume fraction of Al2O3 was not enough to compensate the loss in the power factor of 18 %, leading to a decrease in the figure of merit. Microstructural information obtained by SEM, TEM, and BET was used to elucidate the phase and transport properties. The spark-plasma-sintered bulk sample has a figure of merit that is 35 % higher than the bulk sample consolidated through hot-pressing. [ABSTRACT FROM AUTHOR]

SUMMARY The authors have devised a new method to decrease high-frequency harmonics in a specific frequency band by modifying the switching transient slope. In previous studies, there were several problems in applying modified transient pulse width modulation (MT-PWM) to actual converters. In this paper, three problems are solved using an improved MT-PWM method. First, the MT-PWM signal was obtained using a trial-and-error approach that involved complex computation procedures in the previous studies. In this paper, a new calculation procedure for obtaining the MT-PWM waveform using a simple calculation is proposed. Second, a new [ABSTRACT FROM AUTHOR]

A unified structure model for the homologous compounds Ga2O3(ZnO)m in (3 + 1)‐dimensional superspace was modified by refinements for samples of Ga2O3:ZnO = 1:n (n = 15, 23, 28, 33, 38). The first‐order sine terms in the modulation functions decreased with increasing phase index m. The diffraction intensities of the thermoelectric material Ga2O3:ZnO = 1:98 were best fitted by a two‐phase model containing the wurtzite structure (Ga‐doped ZnO) and the homologous compound Ga2O3(ZnO)s, where s = 38. [ABSTRACT FROM AUTHOR]

Current high-performance thermoelectric materials require elaborate doping and synthesis procedures, particularly in regard to the artificial structure, and the underlying thermoelectric mechanisms are still poorly understood. Here, we report that a natural chalcopyrite mineral, Cu1+xFe1−xS2, obtained from a deep-sea hydrothermal vent can directly generate thermoelectricity. The resistivity displayed an excellent semiconducting character, and a large thermoelectric power and high power factor were found in the low x region. Notably, electron-magnon scattering and a large effective mass was detected in this region, thus suggesting that the strong coupling of doped carriers and antiferromagnetic spins resulted in the natural enhancement of thermoelectric properties during mineralization reactions. The present findings demonstrate the feasibility of thermoelectric energy generation and electron/hole carrier modulation with natural materials that are abundant in the Earth's crust. [ABSTRACT FROM AUTHOR]

Layered materials have several properties that make them suitable as high-performance thermoelectric materials. In this study, we elucidated the potential of d0-electron layered complex metal nitrides, AMN2 (A = Sr or Ba; M = Ti, Zr, Hf), with KCoO2-type and α-NaFeO2-type crystal structures. The detailed electronic structures and electronic transport coefficients for AMN2 compounds were calculated by using density-functional theory and Boltzmann theory, respectively. The KCoO2-type AMN2 compounds show highly anisotropic thermoelectric properties. The effective masses at the lowest conduction bands in both KCoO2-type and α-NaFeO2-type AMN2 compounds were significantly smaller than that in three-dimensional perovskite SrTiO3, a well-known compound with good thermoelectric properties. The results suggest that the excellent thermoelectric transport properties arise from appropriate electronic structures and small effective masses in AMN2 layered complex metal nitrides. [ABSTRACT FROM AUTHOR]

Cover Feature: Thermoelectric properties of Cu-Doped Heusler compound Fe2-xCuxVAl (Z. Anorg. Keywords: Heusler compounds; Electrical resistivity; Seebeck coefficient; Thermal conductivity; ZT EN Heusler compounds Electrical resistivity Seebeck coefficient Thermal conductivity ZT 1 1 1 08/19/22 20220812 NES 220812 The cover picture shows co-doping of Cu for Fe and Si for Al site in Fe SB 2 sb VAl, and the effect of Cu doping to significantly enhance the thermoelectric power factor. Heusler compounds, Electrical resistivity, Seebeck coefficient, Thermal conductivity, ZT. [Extracted from the article]

High-quality NdB6 nanostructures with a low work function are successfully synthesized via an one-step catalyst-free chemical vapor deposition process. Field emission properties of these nanostructures (curve nanowires, short-straight nanorods, long-straight nanowires, and nanoneedles) are systematically investigated and found to be strongly affected by the tip morphologies and temperatures. The nanoneedles with sharp tips demonstrate the lowest turn-on (2.71 V/μm) and threshold (3.60 V/μm) electric fields, as well as a high current density (5.37 mA/cm2) at a field of 4.32 V/μm in comparision with other nanostructures. Furthermore, with an increase in temperature from room temperature to 623 K, the turn-on field of the nanoneedles decreases from 2.71 to 1.76 V/μm, and the threshold field decreases from 3.60 to 2.57 V/μm. Such excellent performances make NdB6 nanomaterials promising candidates for application in flat panel displays and nanoelectronics building blocks. [ABSTRACT FROM AUTHOR]

The structure of (Ga2O3)2(ZnO)13 has been determined by a single-crystal X-ray diffraction technique. In the monoclinic structure of the space group C2/ m with cell parameters a = 19.66 (4), b = 3.2487 (5), c = 27.31 (2) Å, and β = 105.9 (1)°, a unit cell is constructed by combining the halves of the unit cell of Ga2O3(ZnO)6 and Ga2O3(ZnO)7 in the homologous series Ga2O3(ZnO) m. The homologous series (Ga2O3)2(ZnO)2 n + 1 is derived and a unified description for structures in the series is presented using the (3+1)-dimensional superspace formalism. The phases are treated as compositely modulated structures consisting of two subsystems. One is constructed by metal ions and another is by O ions. In the (3 + 1)-dimensional model, displacive modulations of ions are described by the asymmetric zigzag function with large amplitudes, which was replaced by a combination of the sawtooth function in refinements. Similarities and differences between the two homologous series (Ga2O3)2(ZnO)2 n + 1 and Ga2O3(ZnO) m are clarified in (3 + 1)-dimensional superspace. The validity of the (3 + 1)-dimensional model is confirmed by the refinements of (Ga2O3)2(ZnO)13, while a few complex phenomena in the real structure are taken into account by modifying the model. [ABSTRACT FROM AUTHOR]

Keywords: chemical bond weakening; Heikes' equation; SnTe; thermoelectrics EN chemical bond weakening Heikes' equation SnTe thermoelectrics 1 1 1 07/29/21 20210728 NES 210728 In article number 2101122, Bhuvanesh Srinivasan, David Berthebaud, Takao Mori and co-workers show that by strategically weakening the chemical bonds and increasing the anharmonicity in Zr/Ti-Mn inserted SnTe, high thermoelectric efficiency can be attained with a much lower temperature gradient without the requisite for a stupendous peak figure of merit, and also discuss the applicability of Heikes' equation. Thermoelectrics: Physical Insights on the Lattice Softening Driven Mid-Temperature Range Thermoelectrics of Ti/Zr-Inserted SnTe - An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes' Equation for Estimating Carrier Properties (Adv. Chemical bond weakening, Heikes' equation, SnTe, thermoelectrics. [Extracted from the article]