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We demonstrate reversible modulation of an insulator–metal transition (IMT) of a VO2 film grown on an Al2O3 (001) substrate through crystallization and re-amorphization of a chalcogenide germanium–antimony–telluride (Ge2Sb2Te5: GST) capping layer. After succeeding in the negative shift of IMT temperature (Tr) of the VO2 film through the crystallization of the GST layer accompanied by volume reduction, we performed re-amorphization of the crystalline GST by femtosecond laser irradiation. Under the optimized conditions of laser irradiation considering the penetration depth, re-amorphization of the GST layer was fully achieved, resulting in the shift-back of Tr toward a high-temperature side. Such a reversal of IMT through the crystallization and re-amorphization of the capping GST layer was demonstrated over two cycles. It was suggested that capping GST effectively induces interfacial strain modifications in the VO2 film underneath. Although the shifts in the IMT are still small, reversible modulation of IMT shown here will be beneficial for applications of VO2 films with controllable IMT. [ABSTRACT FROM AUTHOR]

Gap opening remains elusive in copper chalcogenides (Cu2X, X = S, Se, and Te), not least because Hubbard + U, hybrid functional, and GW methods have also failed. In this work, we elucidate that their failure originates from a severe underestimation of the 4s–3d orbital splitting of the Cu atom, which leads to a band-order inversion in the presence of an anionic crystal field. As a result, the Fermi energy is pinned due to symmetry, yielding an invariant zero gap. Utilizing the hybrid pseudopotentials to correct the underestimation on the atomic side opens up gaps of experimental magnitude in Cu2X, suggesting their predominantly electronic nature. Our work not only clarifies the debate about the Cu2X gap but also provides a way to identify which of the different methods really captures the physical essence and which is the result of error cancellation. [ABSTRACT FROM AUTHOR]

The massive amount of wasted heat energy from industry has pushed the development of thermoelectric (TE) materials that directly convert heat into electricity to a new level of concern. Recently, multicomponent alloys such as GeTe-based and PbSe-based high-entropy (HE) chalcogenides have attracted a great deal of attention due to their potential application as TE materials. The nature of the interatomic bonding, lattice distortion (LD), and the electronic structure in this class of materials is not fully understood. Herein, we report a comprehensive computational investigation of nine GeTe-based HE alloys with eight metallic elements (Ag, Pb, Sb, Bi, Cu, Cd, Mn, and Sn) with large supercells of 1080 atoms each; seven PbSe-based HE solid solutions: Pb0.99−ySb0.012SnySe1−2xTexSx (x = 0.1, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, with y = 0) with supercells of 1000 atoms each; and five Pb0.99−ySb0.012SnySe1−2xTexSx (y = 0.05, 0.1, 0.15, 0.2, 0.25 with x = 0.25) solid solutions with supercells of 1000 atoms each. All these HE models are theoretically investigated for the first time. The electronic structure, interatomic bonding, charge transfer, and lattice distortion (LD) are investigated by first-principles calculations based on density functional theory. Multicomponent HE alloys can cause a significant LD, which affects their mechanical, thermal, and TE properties. The calculations for the GeTe-based HE chalcogenides showed that they are semiconductors with a narrow bandgap, except for m8, which has a semi-metallic characteristic, and this makes them good candidates for TE applications. For most of these models, the Fermi level shifts upward and locates deeply in the conduction bands, resulting in the enhancement of the electrical conductivity (σ). The bonding properties showed that most bonds in m5 are more dispersed, indicating highest LD and lower lattice thermal conductivity. For PbSe-based HE solid solutions, the LD calculations showed that the models Pb0.99Sb0.012Se0.5Te0.25S0.25 and Pb0.89Sb0.012Sn0.1Se0.5Te0.25S0.25 have the higher LD, and thus a lower lattice thermal conductivity. Such investigations are in high demand since it enables us to design new HE chalcogenides for TE applications. We use the novel concept of total bond order density as a single quantum mechanical metric to characterize the internal cohesion of these HE alloys and correlate with calculated properties, especially the mechanical properties. This work provides a solid database for HE chalcogenides and a road map for many potential applications. Moreover, the computational procedure we developed can be used to design new HE chalcogenides for specific TE applications. [ABSTRACT FROM AUTHOR]

We demonstrate modulation of insulator metal transition (IMT) of VO2 films grown on single crystalline substrates through the effect of in-plane compression with crystallization of capping chalcogenide layer on the targeted VO2 films. Chalcogenide germanium–antimony–telluride (Ge2Sb2Te5: GST), which shows large volume reduction of 6.8% with its phase change from amorphous to crystal, was deposited on VO2 films grown on Al2O3 (001) and TiO2 (001) substrates, where V–V atoms along the cR-axis in the tetragonal VO2 phase align parallel and perpendicular to the substrate surfaces, respectively. As a result, counter shifts in temperature-dependence of resistance characteristics, to lower and higher directions, were observed for VO2 films on Al2O3 (001) and TiO2 (001), consistent with the lattice modulation of VO2 films by the in-plane compression introduced by GST crystallization. The obtained results open a way to realize large resistance change of IMT under constant temperature by controlling GST phases. [ABSTRACT FROM AUTHOR]

Pb-based chalcogenides display abundant structural diversity and distinguished properties. Based on a mixed anion and dimensional reduction combined strategy, a wide band gap Pb-based thiohalide, Pb6Ba3Si2S8I10, has been rationally designed and synthesized experimentally by the flux method. The compound crystallizes in the R3¯c space group with cell parameters a = 9.7925(2) Å, b = 9.7925(2) Å, and c = 70.628(3) Å and is composed of [SiS4] tetrahedra and unprecedented [PbI5S2] polyhedral units, resulting in a unique quasi-two-dimensional structure, which enriches the chemical and structural diversity of Pb-based thiohalides. The experimental band gap of Pb6Ba3Si2S8I10 was determined to be 2.80 eV. Based on statistical analyses and to the best of our knowledge, it is the largest experimental optical band gap among the known Pb-based thiohalides. The results demonstrate the feasibility of using highly electropositive Ba atoms to regulate the dimensions of the structural framework of thiohalides and give new insights into the structure and property modifications of thiohalides by the mixed anion and dimensional reduction combined strategy. [ABSTRACT FROM AUTHOR]

A new avenue by transforming the conventional electrochemical domain into an electro‐chemo‐mechanical domain is proposed to achieve less hysteretic fast‐charging based on the three pictures: i) electro‐chemo‐mechanics, ii) phase transition kinetics, and iii) ionic kinetics. Each concept is demonstrated leading to the electrochemical improvement using data‐driven computation and experimental analyses, and its novel framework is generalized based on alkali‐ion chalcogenide models. The mechanical strain lowers and delays the electrochemical yield point, which gives rise to extending the elastic region and enhancing the phase and ionic kinetics. This is experimentally verified with less hysteresis upon (dis)charging for all models. Implementing the electro‐chemo‐mechanical domain is central in alkali‐ion chalcogenide batteries and broadens its application in other rechargeable batteries, ultimately playing a critical role in providing practical fast‐charging solutions. [ABSTRACT FROM AUTHOR]

Structural, electronic, magnetic and optical properties of Cu4Mn2Te4 have been reported earlier by the authors, and here, the transport properties of the same are discussed along with the band structure investigation of the neodymium-doped cubic material LMO (LiMn2O4), namely LiMn 1. 7 5 Nd 0. 2 5 O4 compound, under spin polarized schemes through the First Principles calculations. The Full Potential-Linearized Augumented Plane Wave Method (FP-LAPW) method is adopted to investigate the electronic structures based on the framework of Density Functional Theory (DFT). Exchange potentials are treated using the Generalized Gradient Approximations (GGA). Cohesive energy calculations reveal that the ferromagnetic phase of LiMn 1. 7 5 Nd 0. 2 5 O4 and the antiferromagnetic phase of Cu4Mn2Te4 exhibits a stable phase. Of these, FM-LiMn 1. 7 5 Nd 0. 2 5 O4 shows a semi-metallic-like behavior in spin-up channel and metallic behavior in spin-down channel whereas antiferromagnetic Cu4Mn2Te4 exhibits a band gap in both spin-up and spin-down channels. Dirac points are identified at −0.0625 eV in the band structure plot of FM-LiMn 1. 7 5 Nd 0. 2 5 O4 at its high symmetry points Γ and W which is an indication of high electron mobility at ambient condition. The presence of flat and dispersive bands around the Fermi energy level is an indication of high thermopower, and it is present in both the compounds FM-LiMn 1. 7 5 Nd 0. 2 5 O4 and AFM-Cu4Mn2Te4. From the present computations, at 300 K, a power factor range of ( S 2 σ scaled by relaxation time in μ W/msK2) 1. 7 5 × 1 0 2 0 ↑ and 9. 3 7 × 1 0 2 1 ↓ is obtained for ferromagnetic LiMn 1. 7 5 Nd 0. 2 5 O4 compounds at up and down spins, respectively. A typical power factor (μ Wm − 1 s − 1 K − 2 ) of 4. 7 9 × 1 0 1 5 ↑ and 2. 9 7 × 1 0 1 8 ↓ is obtained for antiferromagnetic Cu4Mn2Te4 at 325 K required for good thermoelectric performance. [ABSTRACT FROM AUTHOR]

We design and simulate a near-zero flat dispersion As2S3 photonic crystal fiber (PCF) with a circular shape to generate a broad and smooth supercontinuum (SC). A near-zero flattened dispersion in the all-normal dispersion PCF is maintained in the 4–6.2 μ m wavelength range. A 6 μ m hyperbolic pulse is injected into this fiber, producing a flat spectrum from 2.45 to 8.4 μ m at a peak power of 5 kW. The generated SC in anomalous dispersion PCF can cover multi-octaves by a pump laser with a 6500 nm wavelength, 10 kW of peak power, and a 90 fs duration in 10 cm of the proposed fiber structure. These results are achieved by optimizing the fiber structure through the core size. In general, the proposed structures could be used for broadband smooth low-cost SC generation. [ABSTRACT FROM AUTHOR]

The unique combination of excellent semiconducting properties in halide perovskites and the high stability and nontoxicity of oxide perovskites has led to a recent surge in interest in chalcogenide perovskite BaZrS3 for optoelectronic applications. However, to realize its potential in future device technologies, a comprehensive understanding of photoexcited carrier dynamics and transient optical response is imperative, yet it remains largely unexplored for BaZrS3. In this work, employing transient absorption spectroscopy, we have revealed that photoexcited carriers in epitaxial BaZrS3 nanofilms exhibit two exponential decay components relating to optical phonon cooling and interband recombinations. Meanwhile, our investigation unveils an intriguing transient nonlinear absorption phenomenon in BaZrS3, characterized by the ultrafast switching of the pump-induced transparency (i.e., the saturable absorption) to the absorption enhancement within a timescale commensurate with the measurement resolution (hundreds of femtosecond). This study provides crucial dynamic insights essential for leveraging chalcogenide perovskites, such as BaZrS3, in the development of advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

In recent times, diaryliodonium reagents (DAIRs) have witnessed a resurgence as arylating reagents, especially under photoinduced conditions. However, reactions proceeding through electron donor‐acceptor (EDA) complex formation with DAIRs are restricted to electron‐rich reacting partners serving as donors due to the well‐known cage effect. We discovered a practical and high‐yielding visible‐light‐induced EDA platform to generate aryl radicals from the corresponding DAIRs and use them to synthesize key chalcogenides. In this process, an array of DAIRs and dichalcogenides react in the presence of 1,4 diazabicyclo[2.2.2]octane (DABCO) as a cheap and readily available donor, furnishing a variety of di(hetero)aryl and aryl/alkyl chalcogenides in good yields. The method is scalable, features a broad scope with good yields, and operates under open‐to‐air conditions. The photoinduced chalcogenation technology is suitable for late‐stage functionalizations and disulfide bioconjugations and facilitates access to biologically relevant thioesters, dithiocarbamates, sulfoximines, and sulfones. Moreover, the method applies to synthesizing diverse pharmaceuticals, such as vortioxetine, promazine, mequitazine, and dapsone, under amenable conditions. [ABSTRACT FROM AUTHOR]

Nanoparticles can offer an alternative approach to fabricate phase‐change materials. The chemical synthesis of GeTe nanoparticles using organometallic precursors exploits high‐boiling solvents and relatively high temperatures (close or even above crystallization temperatures), as reported in the available literature. The aim of this work is the preparation of GeTe nanoparticles by a low‐temperature synthetic method exploiting new organometallic precursors and common organic solvents. Indeed, different preparation methods and characterization of GeTe nanoparticles is discussed. The characterization of the prepared nanomaterial was performed on the basis of X‐ray diffraction, transmission electron microscopy, scanning electron microscopy with energy dispersive X‐ray spectroscopy, laser ablation time‐of‐flight mass spectrometry, Raman scattering spectroscopy, and dynamic light scattering. The results show that the low‐temperature synthetic route leads to amorphous GeTe nanoparticles. Exploited organometallic precursor is stabilised by neutral ligand which can be isolated after the reaction and repeatedly used for further reactions. Furthermore, GeTe nanoparticle size can be tuned by the conditions of the synthesis. [ABSTRACT FROM AUTHOR]

The thermoelectric material PdSe2$\left(\text{PdSe}\right)_{2}$ in orthorhombic (Pbca) phase is studied with the help of density functional theory implemented in WIEN2k. The main properties of PdSe2$\left(\text{PdSe}\right)_{2}$ investigated are elastic, electronic, and thermoelectric properties. The anisotropy factors obtained with the elastic constants indicate that PdSe2$\left(\text{PdSe}\right)_{2}$ is strongly anisotropic. The Tran and Blaha‐modified Becke–Johnson exchange potential is used for bandgap calculations. The BoltzTraP code is used to find out the thermoelectric properties of PdSe2$\left(\text{PdSe}\right)_{2}$. At 300 K, the maximum value of the Seebeck coefficient is 200 μV K−1 for the hole carrier concentration of 2.5 × 1019 cm−3 and is 241 μV K−1 for the electron carrier concentration of 1.2 × 1019 cm−3. The power factor (PF) and figure of merit (ZT) are calculated for different carrier concentrations and temperatures. The optimum value of ZT for bulk PdSe2 as calculated in this work is ≈0.6 for hole carrier concentration (p = 2.6 × 1020 cm−3) at 800 K, which suggests PdSe2$\left(\text{PdSe}\right)_{2}$ as a potential material in thermoelectric applications at higher temperatures. [ABSTRACT FROM AUTHOR]

The unique combination of excellent semiconducting properties in halide perovskites and the high stability and nontoxicity of oxide perovskites has led to a recent surge in interest in chalcogenide perovskite BaZrS3 for optoelectronic applications. However, to realize its potential in future device technologies, a comprehensive understanding of photoexcited carrier dynamics and transient optical response is imperative, yet it remains largely unexplored for BaZrS3. In this work, employing transient absorption spectroscopy, we have revealed that photoexcited carriers in epitaxial BaZrS3 nanofilms exhibit two exponential decay components relating to optical phonon cooling and interband recombinations. Meanwhile, our investigation unveils an intriguing transient nonlinear absorption phenomenon in BaZrS3, characterized by the ultrafast switching of the pump-induced transparency (i.e., the saturable absorption) to the absorption enhancement within a timescale commensurate with the measurement resolution (hundreds of femtosecond). This study provides crucial dynamic insights essential for leveraging chalcogenide perovskites, such as BaZrS3, in the development of advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

Beyond the high theoretical capacity, conversion‐alloying metal chalcogenides (CAMCs) exhibit exceptional high‐rate performance as Li‐ion battery electrodes. However, the inherent origin of the high‐rate performance remains elusive, especially given the lower intrinsic conductivity of CAMCs. Here, the correlation between phase evolution and charge transport dynamics in fully activated CAMCs is systematically investigated, elucidating a current‐adaptive Li‐ion storage mechanism to explain the anomalous high‐rate performance. Briefly, the deconversion reaction manipulated by ion diffusion acts as a "regulator" to adaptively modulate the transition from metal (high electronic conductivity) and lithium chalcogenides (high ionic conductivity) to CAMCs, thus removing the charge transport bottleneck without affecting the formation of the metal feedstock required for the alloying reaction. On this basis, the high capacity can be maintained at high rates through a "fading‐free" alloying reaction. This study offers a novel perspective for the design of high‐rate electrode materials. [ABSTRACT FROM AUTHOR]

Water electrolysis plays a vital role in green energy systems and there is an absolute need for abundant, affordable, and effective catalysts for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Despite existing challenges, the exploration of transition metal‐based electrocatalysts with superior performance in alkaline water splitting is critical for advancing the hydrogen economy. This study focuses on the electrocatalytic potentials of FeS2, CoSe2, and FeS2@CoSe2 hybrid nanocomposites in response to the increasing demand for sustainable energy production. The prepared materials were synthesized hydrothermally and characterized using X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), energy‐dispersive X‐ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) to examine their structural properties, elemental composition, and morphological features. Notably, the F@C−B nanocomposite exhibited outstanding HER performance, requiring only 97 mV of overpotential to achieve a current density of 10 mA cm−2. Similarly, the F@C−C nanocomposite demonstrated impressive OER efficiency with an overpotential of merely 302 mV at the same current density. The involvement of the Volmer–Heyrovsky mechanism was confirmed through Tafel slope analysis, revealing the improved surface‐active sites and reduced charge transfer resistance of the nanocomposite. The FeS2@CoSe2 nanocomposite with synergistic effects, displayed exceptional electrocatalytic properties, positioning it as a promising candidate for overall water splitting. This work introduces a novel approach to developing highly efficient and cost‐effective electrocatalysts, offering a viable alternative to precious metal‐based counterparts. [ABSTRACT FROM AUTHOR]

Plasmonic copper chalcogenide (Cu2−xE, E = S, Se, Te) nanoparticles (NPs) possess high potentials in photothermal therapy and photoacoustic tomography for their unique localized surface plasmon resonant absorption in the second near-infrared biologically transparent window. In this study, strong thermal-induced nonlinear negative-lens effect in aqueous suspensions containing Cu2−xSe NPs was observed. Furthermore, the nonlinear absorption was notably enhanced in aqueous suspensions containing Au@Cu2−xSe core–shell NPs, as the positive nonlinear absorption coefficient increased by 20-fold, attributed to the strong plasmonic coupling in Au@Cu2−xSe core–shell NPs. This finding underscores the importance of the nonlinear optical behaviors of plasmonic NPs in biomedical applications, as they offer extra strategy for optimizing systems and incorporating additional functionalities. [ABSTRACT FROM AUTHOR]

In this study, the first fabrication of phase‐shifted Bragg gratings utilizing chalcogenide hybrid inorganic/organic polymers (CHIPs) is presented based on poly(sulfur‐random‐(1,3‐isopropenylbenzene) to measure the thermo‐optic coefficient (TOC) of this new class of optical polymers. The unique properties of CHIPs, such as high index contrast and low optical losses, are leveraged to fabricate Bragg gratings that enable precise determination of the TOC and glass transition temperature (Tg) of these polymers. The optical measurement introduces a novel technique to measure the TOC and Tg of optical polymers which can be difficult to determine using traditional methods such as differential scanning calorimetry (DSC) after fabrication into photonic device constructs. The findings demonstrate that CHIPs exhibit low thermo‐optic (TO) effects, making them exceptionally well‐suited for the development of thermally stable photonic integrated circuits. [ABSTRACT FROM AUTHOR]

Starting from ClSbRF2 (RF = C2F5, 3,5-(CF3)2C6H3) and H(E)P(tBu)2 (E = O, S), we prepared the oxy- and sulphanediyl-bridged adducts RF2Sb(Cl)–E–(H)P(tBu)2, which are stable against the elimination of HCl. The different electron-withdrawing substituents and chalcogen bridging units influence the size of the Sb–E–P angle. ClSb(C2F5)2 and nBu3SnH react to give HSb(C2F5)2, which seems to interact weakly with H(O)P(tBu)2 in solution as observed via NMR. All products were characterised by NMR spectroscopy and all the stable ones were additionally characterised by X-ray diffraction and elemental analyses. [ABSTRACT FROM AUTHOR]

Two new non‐centrosymmetric chalcogenides, ACuGa6S10 (A=Rb, Cs) have been successfully synthesized by an “iterative substitution” strategy based on chalcopyrite CuFeS2 structural template. Benefiting from the substitution of Fe3+ cations by Ga3+ cations, ACuGa6S10 (A = Rb, Cs) exhibit wide suitable band gap of 2.48 and 2.40 eV, respectively, which is about five times higher than their structure template CuFeS2, and a large second harmonic generation response (1.5 and 1.8×AgGaS2). Combining theoretical calculation and structural analysis confirms that the [GaS4] tetrahedra make the main contribution on their good liner and nonlinear optical (NLO) performances. The “iterative substitution” strategy expands the design idea of materials and can lead to the discovery of a large number of IR NLO compounds. [ABSTRACT FROM AUTHOR]

Solar cells based on Sb2(S1−x,Sex)3 ternary compounds have shown the highest reported efficiency value compared to their Sb2Se3 and Sb2S3 counterparts in antimony chalcogenide technology. However, the reported record efficiencies for these new emergent solar cells are still well below the theoretical values according to their bandgap value or for the traditional solar cells in the thin film technology. This article presents an analysis regarding the optimal composition that guarantees an increase in efficiency in the manufacture of Sby(S1−x,Sex)3 solar cells, as well as the proposal of a new synthesis method that allows obtaining the ternary compound with the calculated optimal composition. From theoretical considerations, a composition of Sb1.85(S0.63,Se0.42)3 is obtained. This composition is equivalent to optimal values Se/(S + Se) = 0.4 and Sb/(S + Se) = 0.88. The results of the new proposed synthesis method are presented and discussed. [ABSTRACT FROM AUTHOR]

The current investigation employs first‐principles DFT (density functional theory) calculations to examine the influence of transition metal replacements on the structural, thermodynamic, and thermoelectric properties of Cu‐based chalcogenides TMCu3Se4 (TM = Nb/Ta/V). The PBE‐generalized gradient approximation (GGA) model is utilized to compute the fundamental properties of Cu‐based chalcogenides under study. A thorough examination of the energy band structures indicates that these chalcogenides are semiconductor compounds with indirect energy bandgaps. We can infer from the calculated energy band structures that the bandgap values are 1.67, 1.77, and 1.05 eV for NbCu3Se4, TaCu3Se4, and VCu3Se4, respectively. The ZTe$$ {\mathrm{ZT}}_e $$ values for NbCu3Se4, TaCu3Se4, and VCu3Se4 are 0.661, 0.998, and 0.996, respectively. These values make them highly appropriate for usage in thermoelectric (TE) devices. The thermoelectric characteristics of pyrochlore oxides TMCu3Se4 (TM = Nb/Ta/V) suggest that these materials have promising potential for energy‐related applications. The analyzed thermodynamic properties demonstrate that the Cu0based chalcogenide materials TMCu3Se4 (TM = Nb/Ta/V) exhibit a notable level of thermal stability. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur batteries (LSBs) are regarded as one of the most promising candidates for next‐generation energy storage systems. However, the commercialization of LSBs is still hindered by several technical issues, including the notorious polysulfide migration from the cathode to the anode and the sluggish sulfur conversion kinetics. Herein, a quasi‐1D hexagonal chalcogenide perovskite, Sr8Ti7S21, is demonstrated as an efficient sulfur host able to overcome these limitations. Experimental results and density functional theory calculations show Sr8Ti7S21 to offer strong lithium polysulfides (LiPS) binding through multiple bond formation. Besides, Sr8Ti7S21 effectively facilitates the kinetics of the LiPS redox reaction. As a result, S@Sr8Ti7S21‐based cathodes exhibit excellent initial capacities up to 1315 mAh g−1 at 0.2C, impressive cycling stability with an average capacity decay rate of 0.08% per cycle over 400 cycles at 1C, and a high areal capacity of 6.58 mAh cm−2 under a high sulfur loading of 6.5 mg cm−2. This work reveals the potential capabilities and promising prospects of chalcogenide perovskites in advancing LSBs technology. [ABSTRACT FROM AUTHOR]

ABSTRACT Energy‐efficient semiconducting BaS:MnS:Sb2S5 has been synthesized using a single source precursor method. The resulting dithiocarbamate metallic sulfide has an average crystallite size of 17.77 nm and a small band gap of 3.82 eV. A functional group investigation revealed the presence of several bonds, including the metal sulfide bond. This sulfide exhibited a double‐step thermal breakdown pattern. BaS:MnS:Sb2S5 particles were formed like cubes and tended to form cube‐like formations. The electrochemical charge‐storing behavior of BaS:MnS:Sb2S5 was investigated using a nickel foam electrode and a sulfide slurry. The fabricated electrode demonstrated a satisfactory capacity for charge storage, with a specific capacitance of 762.83 F g−1. This indicates a substantial amount of potential for long‐term energy storage utilizing electrodes. This electrode has a specific power density of 9084.78 W kg−1 and a low series resistance of (Rs) = 0.71 Ω, as per impedance measurements. Electro‐catalysis produced an OER overpotential and a corresponding Tafel slope of 233 mV and 157 mV/dec from the electrode. Conversely, for HER activity, the obtained overpotential and subsequent Tafel slope were 386 mV and 73 mV dec−1, respectively. [ABSTRACT FROM AUTHOR]

By engineering chemically identical but structurally distinct materials into intricate and sophisticated polytypic nanostructures, which often surpass their pure phase objects and even produce novel physical and chemical properties, exciting applications in the fields of photovoltaics, electronics and photocatalysis can be achieved. In recent decades, various methods have been developed for synthesizing a library of polytypic nanocrystals encompassing IV, III–V and II–VI polytypic semiconductors. The exceptional performances of polytypic metal chalcogenide nanocrystals have been observed, making them highly promising candidates for applications in photonics and electronics. However, achieving high-precision control over the morphology, composition, crystal structure, size, homojunctions, and periodicity of polytypic metal chalcogenide nanostructures remains a significant synthetic challenge. This review article offers a comprehensive overview of recent progress in the synthesis and control of polytypic metal chalcogenide nanocrystals using colloidal synthetic strategies. Starting from a concise introduction on the crystal structures of metal chalcogenides, the subsequent discussion delves into the colloidal synthesis of polytypic metal chalcogenide nanocrystals, followed by an in-depth exploration of the key factors governing polytypic structure construction. Subsequently, we provide comprehensive insights into the physical properties of polytypic metal chalcogenide nanocrystals, which exhibit strong correlations with their applications. Thereafter, we emphasize the significance of polytypic nanostructures in various applications, such as photovoltaics, photocatalysis, transistors, thermoelectrics, stress sensors, and the electrocatalytic hydrogen evolution. Finally, we present a summary of the recent advancements in this research field and provide insightful perspectives on the forthcoming challenges, opportunities, and future research directions. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) was used to study the structural, electronic, magnetic, and optical properties of the rare-earth-based ternary chalcogenide GdCuX2 (X = S, Se, and Te). DFT calculations were performed using the Tran-Blaha modified Becke-Johnson (TB-mBJ) generalized gradient approximation (GGA), generalized gradient approximation with Hubbard U (GGA + U), and spin orbit coupling (GGA + U + SOC) potentials. In structural properties, we computed the ground state energy, with equilibrium volume, and lattice parameters for GdCuS2, GdCuSe2, and GdCuTe2 compounds. The structural properties show that the GdCuS2, GdCuSe2 and GdCuTe2 compounds have stable structures at the Wycoff position. The electronic properties were calculated in terms of the density of states (DOS) and electronic band diagram. Electronic properties confirm the semiconductor nature of GdCuS2, GdCuSe2, and GdCuTe2 compounds using TB-mBJ, GGA, and GGA + U potentials. However, the GdCuTe2 compound displays a metallic nature when using the GGA + U + SOC potential. Magnetic properties in terms of spin polarization magnetic moments of GdCuS2, GdCuSe2 and GdCuTe2 compounds. With magnetic optimisation, we made a graph of the energy vs. volume curve to show that ferromagnetic [FM] is more stable than antiferromagnetic [AFM] and nonmagnetic [NM]. The GdCuS2, GdCuSe2 and GdCuTe2 compounds show a good ferromagnetic nature. The optical properties of the compounds in terms of dielectric functions, refractive indices, and absorption coefficients. In the visible and infrared ranges, the optical properties reveal an upstate semiconductor nature and a downstate metallic nature. In the higher energy range, the maximum absorption is observed in the optical properties. [ABSTRACT FROM AUTHOR]

In this study, we investigate an optimized design of ZnO/BaZrS3/BaZr1−0.95Ti0.05S3 chalcogenide perovskites solar cells using a theoretical model that considers different recombination mechanisms effect in terms of bulk recombination, interface recombination and tunneling enhanced recombination. The influence of thickness and doping of both window and absorber layers, as well as the absorber band gap, was investigated using the proposed model. The model was validated through numerical simulations, showing a good agreement. The proposed model is utilized as the fitness criterion within the MOPSO framework to optimize the solar cell performance. The optimized design achieved an efficiency of 12.26%, outperforming the conventional design with an efficiency of 8.66%. This significant improvement underscores the effectiveness of tuning band alignment at the interface and also to the global design optimization strategy in enhancing the performance of chalcogenide perovskite solar cells. [ABSTRACT FROM AUTHOR]

The reactions of the dianion [Li2(Et2O)1.5][(SPh2P)2C] 1 with Se and Te were explored and shown to be dependent on the stoichiometry. The species, [Li2(THF)3(SPh2P)2CSe2] 2, [Li2(THF)4(SPh2P)2CSe4C(PPh2S)2] 3, [Li2(THF)3(SPh2P)2CTe2] 4 and [Li2(THF)3Et2O][(SPh2P)2CTe3C(PPh2S)2] 5 have been isolated and structurally characterized in the solid state. While these products proved to be remarkably sensitive to light and air, the characterization of these products demonstrates that ability of the dianion to intercept short chalcogenide chains of E2–4. [ABSTRACT FROM AUTHOR]

During our studies of the oxidation of gold(I) complexes of tri­alkyl­phosphane chalcogenides, general formula R¹R²R³PEAuX, (R = tert-butyl or isopropyl, E = S or Se, X = Cl or Br) with PhICl2 or elemental bromine, we have isolated a set of seven mixed-valence by-products, the bis­(tri­alkyl­phosphane chalcogenido)gold(I) tetra­halogenidoaurates(III) [(R¹R²R³PE)2Au]+[AuX4]−. These corres­pond to the addition of one halogen atom per gold atom of the AuI precursor. Com­pound 1, bis­(triiso­propyl­phosphane sulfide)­gold(I) tetra­chlorido­aur­ate(III), [Au(C9H21PS)2][AuCl4] or [(iPr3PS)2Au][AuCl4], crystallizes in space group P21/n with Z = 4; the gold(I) atoms of the two cations lie on twofold rotation axes, and the gold(III) atoms of the two anions lie on inversion centres. Compound 2, bis­(tert-butyl­diiso­propyl­phosphane sulfide)­gold(I) tetra­chlorido­aurate(III), [Au(C10H23PS)2][AuCl4] or [(tBuiPr2PS)2Au][AuCl4], crystallizes in space group P1 with Z = 4; the asymmetric unit contains two cations and two anions with no imposed symmetry. A least-squares fit of the two cations gave an r.m.s. deviation of 0.19 Å. Compound 3, bis­(tri-tert-butyl­phosphane sulfide)­gold(I) tetra­chlorido­aurate(III), [Au(C12H27PS)2][AuCl4] or [(tBu3PS)2Au][AuCl4], crystallizes in space group P1 with Z = 1; both gold atoms lie on inversion centres. Compound 4a, bis­(tert-butyl­diiso­propyl­phosphane sulfide)­gold(I) tetra­bromi­doaurate(III), [Au(C10H23PS)2][AuBr4] or [(tBuiPr2PS)2Au][AuBr4], crystallizes in space group P21/c with Z = 4; the cation lies on a general position, whereas the gold(III) atoms of the two anions lie on inversion centres. Compound 4b, bis­(tert-butyl­diiso­propyl­phosphane selenide)gold(I) tetra­bromido­aurate(III), [Au(C10H23PSe)2][AuBr4] or [(tBuiPr2PSe)2Au][AuBr4], is isotypic with 4a. Compound 5a, bis­(tri-tert-butyl­phosphane sulfide)­gold(I) tetra­bromido­aurate(III), [Au(C12H27PS)2][AuBr4] or [(tBu3PS)2Au][AuBr4], is isotypic with compound 4a. Compound 5a, bis­(tri-tert-butyl­phosphane sulfide)­gold(I) tetra­bromido­aurate(III), [Au(C12H27PS)2][AuBr4] or [(tBu3PS)2Au][AuBr4], crystallizes in space group P1 with Z = 1; both gold atoms lie on inversion centres. Compound 5b, bis­(tri-tert-butyl­phosphane selenide)gold(I) tetra­bromido­aurate(III), [Au(C12H27PSe)2][AuBr4] or [(tBu3PSe)2Au][AuBr4], is isotypic with 5a. All AuI atoms are linearly coordinated and all AuIII atoms exhibit a square-planar coordination environment. The ligands at the AuI atoms are anti­periplanar to each other across the S⋯S vectors. There are several short intra­molecular H⋯Au and H⋯E contacts. Average bond lengths (Å) are: P—S = 2.0322, P—Se = 2.1933, S—Au = 2.2915, and Se—Au = 2.4037. The complex three-dimensional packing of 1 involves two short C—Hmethine⋯Cl contacts (and some slightly longer contacts). For 2, four C—Hmethine⋯Cl inter­actions combine to produce zigzag chains of residues parallel to the c axis. Additionally, an S⋯Cl contact is observed that might qualify as a ‘chalcogen bond’. The packing of 3 is three-dimensional, but can be broken down into two layer structures, each involving an S⋯Cl and an H⋯Cl contact. For the bromido derivatives 4a/b and 5a/b, loose associations of the anions form part of the packing patterns. For all four compounds, these combine with an E⋯Br contact to form layers parallel to the ab plane. [ABSTRACT FROM AUTHOR]

The ternary material Mn2SiTe4 was synthesized by direct fusion using the annealing method. X-ray powder diffraction analysis indicated that this material crystallizes in the olivine-type structure, space group Pnma, Z = 4, with unit cell parameters: a = 13.905(2) Å, b = 8.128(1) Å, c = 6.526(1) Å, V = 737.6(2) Å3. This olivine structure can be described from a hexagonal close-packing of selenium atoms where manganese atoms occupy ½ of the octahedral sites while silicon atoms lay in ⅛ of the tetrahedra. The magnetic susceptibility curve indicate a possible antiferromagnetic behavior for this material. This compound is related to the ternary layered Mn3Si2Te6 recently studied as possible two-dimensional (2D) magnetic material. [ABSTRACT FROM AUTHOR]

Antimony chalcogenide solar cells have captured considerable attention in recent years with an efficiency of over 10%, due to their use of Earth‐abundant materials and superior physical characteristics. Despite these achievements, significant nonradiative recombination processes within these solar cells present a substantial obstacle to further efficiency improvements. Therefore, this review delves into the primary mechanisms responsible for nonradiative recombination losses in antimony chalcogenide solar cells. Additionally, the latest advancements in addressing these losses are summarized. Finally, potential directions for future research efforts aimed at reducing nonrecombination losses and enhancing the overall performance of these devices are outlined. [ABSTRACT FROM AUTHOR]

Thermoelectric materials possess the capability to convert electricity into heat and vice versa. The utilization of chlorofluorocarbons and hydrochlorofluorocarbons as thermal carrier agents in traditional cooling and air conditioning systems has sparked a surge in exploration toward pioneering refrigeration and spatial conditioning technologies. Chalcogenides, known for their capacity to amplify the thermoelectric efficiency of materials and their adaptability across a broad spectrum of temperatures, stand out as pivotal components in thermoelectric materials. Despite their existing suboptimal performance, these materials hold substantial promise as power generators and as solid-state Peltier coolers, attracting significant attention and positioning them as subjects ripe for further investigation. Categorized into alkali or alkaline earth, transition metal, and main-group chalcogenides, these materials and their respective subclasses are meticulously scrutinized to pinpoint the most suitable thermoelectric materials for specific applications with an optimal operational temperature span. In the quest for energy-efficient technologies characterized by simple designs, absence of moving components, and superior stability, thermoelectric materials play a crucial role. This review highlights the advancements in theoretical parameters as well as the figure of merit (ZT) of chalcogenide materials, emphasizing their device applications. These insights are intended to provide viable future approaches to mainstream thermoelectric materials. This review reveals that Cu2Se achieves a maximum ZT value of 2.66 at 1039 K, marking it as the top performer among transition metal chalcogenides. Conversely, SnSe, a main-group metal monochalcogenide, exhibits a ZT value of 2.8 at 773 K, whereas nanowires of the main group of bismuth chalcogenides exhibit a ZT value of 2.5 at 350 K. [ABSTRACT FROM AUTHOR]

Diamond‐like (DL) metal chalcogenides have attracted significant attention in recent years because of their complex structural compositions and exceptional nonlinear optical (NLO) capabilities in the infrared (IR) range. Despite notable advancements in this field, there is still a lack of systematic research on high‐performance and simply composed IR‐NLO chalcogenides with DL structures. In this study, the insightful structural characteristics and IR‐NLO properties of a ternary Ag‐based chalcogenide Ag2GeS3 are investigated for the first time at both experimental and theoretical levels. The compound belongs to the non‐centrosymmetric Cmc21 space group (No.36) and displays a 3D DL structure comprising highly oriented [AgS4] and [GeS4] tetrahedra. Due to its distinct structure, the compound may produce significant second harmonic generation (SHG) response (5.6 × AgGaS2 at 2050 nm), the biggest value reported among Ag‐based IR‐NLO chalcogenides to date, and phase matchability in the IR range with a calculated birefringence of Δn = 0.09 at 2050 nm. According to theoretical calculations, the combined impacts of the distorted [AgS4] and [GeS4] NLO‐active motifs inside the 3D DL framework provide the SHG tensor d24 of Ag2GeS3 at 51.9 pm V−1 at 2050 nm. The prospective uses of Ag2GeS3 in the field of IR‐NLO are highlighted in this work. [ABSTRACT FROM AUTHOR]

Recently, Ni‐based chalcogenides havedemonstrated remarkable activity and selectivity for alcohol electrooxidation, but the mechanisms remain debated. This study synthesizes Ni‐based electrodeswith different chalcogen anion coordination on nickel nanorod arrays (NiOx/Ni,NiSx/Ni, and NiSex/Ni NRAs). NiSex/Ni NRAsshowcases superior performance (Faradaic efficiency 92.9%) in glycerolelectrooxidation reaction (GOR). In situ spectroscopy reveals that NiSecoordination inhibits deep oxidative reconstruction of the Ni‐based interface, preventingNiOOH phase formation during GOR, enhancing activity and stability of NiSex/NiNRAs. Conversely, NiS and NiO coordination lead to deep reconstruction with NiOOHphase formation, limiting GOR performance. Differently, during competingreaction of GOR, the oxygen evolution reaction (OER) leads to deepreconstruction of NiSex interface due to the instability of Ni‐Sebonds, inducing performance degradation and dissolution of Se components. Furthermechanism investigation elucidates that the rate‐determining step (RDS) ofGOR at the NiSex interface involves oxidation of *C2H3O3 intermediatesthrough H2O adsorption, favoring stable formate production.Contrarily, the RDS at the NiSx, NiOx, and NiOOHinterfaces predominantly focus on the decarboxylation of multi‐carbon intermediates, raisingenergy barriers and over‐oxidizing formate to CO2. These results providenew insights for designing Ni‐based non‐oxide catalysts forefficient and stable electrocatalytic oxidation. [ABSTRACT FROM AUTHOR]

Herein, we describe an electrochemical method for the synthesis of haloalkenyl chalcogenides from internal alkynes using hydrobromic and hydrochloric acids as halogenating agents, with the sole byproduct being hydrogen gas. This e‐halochalcogenation protocol generates electrophilic chalcogenium species under mild conditions in a simple, undivided cell setup, enabling the synthesis of 25 examples of chloro‐ and bromovinyl selenides and sulfides with yields ranging from 10 % to 94 %, predominantly as the E‐isomer. The synthetic utility of the halovinyl chalcogenides was demonstrated through various transformations, yielding densely functionalized tetra‐substituted olefins. This underscores the versatility and efficiency of our method in assembling intricate molecular frameworks. [ABSTRACT FROM AUTHOR]

Organophosphorothioates are organic molecules containing sulfur and phosphorus, with significant biological activity and physicochemical properties, widely used in organic synthesis, medicinal chemistry, and the agrochemical industry. In particular, many phosphorothioates display a variety of biological activities, such as antifungal, antibacterial, anti‐parasite, anticancer, and so on. Traditionally, the synthesis of phosphorothioates has mainly relied on indirect methods involving the construction of S−P bond. In recent years, direct phosphorothiolation has gained attention as a reliable and rapid method for introducing the −S−P(O)(OR)2 group into parent molecules. This article reviews the latest advances in direct phosphorothiolation reactions, categorized based on the different sources of the −S−P(O)(OR)2 group. [ABSTRACT FROM AUTHOR]

Engineering new chalcogenide solids improves the desired functionality of the materials and may open the way for new applications. Here we discuss the preparation of As x S 100−x amorphous thin films modified with WS 3 by the sol–gel method. We show that the formation of homogeneous, transparent, and stable n-propylamine-based solutions by mixing 0.02M As x S 100−x and 0.02M (NH 4) 2 WS 4 solutions is feasible for the As content in the chalcogenide glass precursor x ≤ 25 at.%. Above this limit, rapid and massive precipitation occurs in the solutions. We further demonstrate the preparation of amorphous thin films along the pseudo-binary AsS 3 - WS 3 tie-line and provide information about the role of WS 3 on optical properties and the structure of tungsten-based chalcogenide thin films. Due to a significant etching contrast between annealed AsS 3 − WS 3 thin films at 70 and 240 ∘ C , we propose tungsten-based chalcogenide thin films as a suitable platform for application in wet-lithography. [Display omitted] • Homogeneous, transparent, and stable solutions by mixing As x S 100−x and (NH 4) 2 WS 4 solutions for x ≤ 25 at.%. • The WS 3 content increases the thermal stability of prepared thin films. • Optically transparent amorphous AsS 3 − WS 3 thin films up to a molar ratio of 1:3. • As WS 3 increases, the absorption edge is red-shifted. • The chemical resistance decreases to amine-based solutions with increasing WS 3 content. [ABSTRACT FROM AUTHOR]

Antimony selenosulfide Sb2(SxSe1−x)3 is featured as a stable, environment‐friendly, and low‐cost light‐harvesting material with a tunable bandgap in the range of 1.1–1.8 eV, satisfying the requirement of indoor photovoltaics (IPVs). Up to now, the certified efficiency of Sb2(SxSe1−x)3 solar cell with 1.45 eV bandgap has broken 10% under standard illumination (AM1.5G). However, this bandgap is not suitable for IPVs in terms of spectral matching. Herein, for the first time, the effect of optical bandgap of Sb2(SxSe1−x)3 on photovoltaic performance of the devices under AM1.5G and indoor light conditions is studied systematically. It is discovered that although an appropriate Se/S atomic ratio is beneficial for improving the crystallinity of Sb2(SxSe1−x)3 film and passivating the trap states, the band gap remains a key factor in determining the suitability of this material for IPVs. As a result, solar cells based on Sb2S3 with a large bandgap of 1.74 eV achieve an optimal efficiency of 20.34% under 1000 lux indoor illumination. Moreover, a high IPV efficiency of over 16% can still be maintained within a wide bandgap range from 1.5 to 1.7 eV, demonstrating the great potential of Sb‐based chalcogenide as a light‐harvesting material for IPVs. [ABSTRACT FROM AUTHOR]

Large-mode-area anti-resonant fibers (LMA ARF) with high beam quality have the potential to revolutionize mid-infrared high-power laser delivery by mitigating mode instabilities and nonlinear degradation. However, their tens-of-microns mode field diameters and small numerical aperture significantly increase the mode field mismatch and coupling complexity, respectively. In this work, an LMA all-solid anti-resonant fiber-microlens with a robust operation of high beam quality in the mid-infrared region was designed and prepared. It can significantly stabilize the efficiencies of coupling and transmission at a large radial offset. Consequently, this AS-ARF demonstrates substantial potential for advancing mid-infrared laser power delivery via fiber, ensuring exceptional beam quality throughout the process. [ABSTRACT FROM AUTHOR]

The present work elucidates the first report on the synthesis and energy applications of the novel BaLa2MnS5 prepared from single source precursor route. This metal chalcogenide expressed a tuned band gap of 3.84 eV and an average crystallite size of 20.52 nm. Functional groups explored for BaLa2MnS5 expressed strong signals for presence of the metal sulfide bonds. The thermal decomposition pattern of BaLa2MnS5 followed a two‐phased mechanism. Synthesized metal sulfide possessed an irregular morphology with particles arranged in random manner. An assessment of the chalcogenide BaLa2MnS5 for energy applications has been carried out. When employed as an electrode material in 1 M KOH, which acted as the background electrolyte, BaLa2MnS5 chalcogenide showed a specific capacitance of 597 F g−1. Furthermore, this BaLa2MnS5 chalcogenide decorated electrode has a low resistance, as shown by the Rs of 1.35 Ω, and a specific power density of 7366 W kg−1, according to the impedance investigations. The electrochemical results for the OER activity are indicative of the OER overpotential and Tafel slope values as 388 mV and 108 mV/dec. This electrode achieved the HER overpotential value of 241 mV while the obtained Tafel slope was 194 mV/dec. [ABSTRACT FROM AUTHOR]

Materials with large birefringence (Δn, where n is the refractive index) are sought after for polarization control (e.g., in wave plates, polarizing beam splitters, etc.), nonlinear optics, micromanipulation, and as a platform for unconventional light-matter coupling, such as hyperbolic phonon polaritons. Layered 2D materials can feature some of the largest optical anisotropy; however, their use in most optical systems is limited because their optical axis is out of the plane of the layers and the layers are weakly attached. This work demonstrates that a bulk crystal with subtle periodic modulations in its structure-Sr9/8 TiS3 -is transparent and positive-uniaxial, with extraordinary index ne = 4.5 and ordinary index no = 2.4 in the mid- to far-infrared. The excess Sr, compared to stoichiometric SrTiS3 , results in the formation of TiS6 trigonal-prismatic units that break the chains of face-sharing TiS6 octahedra in SrTiS3 into periodic blocks of five TiS6 octahedral units. The additional electrons introduced by the excess Sr form highly oriented electron clouds, which selectively boost the extraordinary index ne and result in record birefringence (Δn > 2.1 with low loss). The connection between subtle structural modulations and large changes in refractive index suggests new categories of anisotropic materials and also tunable optical materials with large refractive-index modulation.

We have simulated Ag–Ge–Te-based conductive bridge RAM (CBRAM) under RF electromagnetic wave input to investigate the RF effects on heat transfer and electrochemical reaction. The RF simulations agreed with the experimental transmission coefficient S21 between 0.4 and 1 GHz, indicating an effective, uniform electric field applied in the RF-applicable CBRAMs. The heat transfer simulations showed a minimal temperature increase of about 1 K under the RF wave at 10 MHz and 10 dBm, indicating negligible thermal effects. The electrochemical simulations were based on the Nernst–Planck equation, taking into account the Ag ion transport in the Ag–GeTe electrolyte by diffusion and migration. Electrode kinetics were calculated for charge transfer reactions using the Butler–Volmer equation. The cathode electrode moved at a velocity equal to the rate of Ag electrodeposition on the cathode. The electrode movement represented filament growth. The electrochemical simulations successfully reproduced filament growth, bipolar resistive switching, experimental currents, and SET/RESET voltages. In addition, the electrochemical simulations under RF waves showed a decrease in the magnitude of SET and RESET voltages, consistent with experimental observations. The RF-induced SET/RESET voltage modulation was attributed to redox reactions that changed the average ion concentration during RF cycles, accelerating filament growth and dissolution. [ABSTRACT FROM AUTHOR]

Zinc chalcogenide nanostructures are an important class of non-toxic nanomaterials due to their biocompatible nature, surface flexibility, high degree of crystallinity, and high photoluminescence efficiency that makes them applicable in solar cells biosensors, photocatalysts, LEDs, and electroluminescence materials. There are various methods for synthesizing zinc chalcogenides, including ZnS, ZnSe, and ZnTe, through colloidal, hydrothermal, solvothermal, microwave, and core shell synthesis to prepare highly luminescent material for drug delivery and biomedical applications. The main focus of this review is to explore various synthetic approaches to tune the morphology, size, and surface properties of zinc-based chalcogenide nanostructures, revealing their potential as biocompatible quantum dots. Despite their advantages, zinc chalcogenides also have certain drawbacks, such as low mechanical strength, limited bandgap tunability, and less thermal stability, that can point the way for future research. Thus, this review may prove beneficial for developing and designing more advanced nanomaterials based on existing knowledge, protocols, and strategies. [ABSTRACT FROM AUTHOR]

Threshold‐switching devices based on amorphous chalcogenides are considered for use as selector devices in 3D crossbar memories. However, the fundamental understanding of amorphous chalcogenide is hindered owing to the complexity of the local structures and difficulties in the trap analysis of multinary compounds. Furthermore, after threshold switching, the local structures gradually evolve to more stable energy states owing to the unstable homopolar bonds. Herein, based on trap analysis, DFT simulations, and operando XPS analysis, it is determined that the threshold switching mechanism is deeply related to the charged state of Se–Se homopolar defects. A threshold switching device is demonstrated with an excellent performance through the modification of the local structure via the addition of alloying elements and investigating the time‐dependent trap evolution. The results concerning the trap dynamics of local atomic structures in threshold switching phenomena may be used to improve the design of amorphous chalcogenides. [ABSTRACT FROM AUTHOR]

The weak bonding of A atoms with MX layers in MAX phases not only enables the selective etching of A layers for MXene preparation but brings about the chance to construct A derivatives/MXene composites via in situ conversion. Here, a facile and general gas‐solid reaction systems are elegantly devised to construct multi‐dimensional MXene based composites including AlF3 nanorods/MXene, AlF3 nanocrystals/MXene, amorphous AlF3/MXene, A filled carbon nanotubes/MXene, layered metal chalcogenides/MXene, MOF/MXene, and so on. The intrinsic effect mechanism of interlayer confinement towards crystal growth, catalytic behavior, van der Waals‐heterostructure construction and coordination reaction are rationally put forward. The tight interface combination and synergistic effect from distinct components make them promising active materials for electrochemical applications. More particularly, the AlF3 nanorods/Nb2C MXene demonstrate bi‐directional catalytic activity toward the conversion between Li2S and lithium polysulfides, which alleviates the shuttle effect in lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Chalcogenide phase-change materials (PCMs) are showing versatile possibilities in cutting-edge applications, including non-volatile memory, neuromorphic computing, and nano-photonics. However, for embedded phase-change memory applications, conventional PCMs suffer from insufficient thermal stability because of their relatively low crystallization temperatures (Tx). Although doping with additional alloying elements could improve the amorphous stability, it also increases the tendency towards compositional partitioning and phase separation. Recently, a two-dimensional (2D) layered compound CrGeTe3 (CrGT) was developed as a PCM, showing a high Tx ~ 276 °C with an inverse change in resistive-switching character upon phase transition. Here, we report a high-throughput materials screening for 2D layered phase-change chalcogenides. We aim to clarify whether the high Tx and the inverse electrical resistance contrast are intrinsic features of 2D PCMs. In total, twenty-five 2D chalcogenides with CrGT trilayer structures have been identified from a large database. We then focused on selected layered tellurides by performing thorough ab initio simulations and experimental investigations and confirming that their amorphous phase indeed has a much higher Tx than conventional PCMs. We attribute this enhanced amorphous stability to the structurally complex nuclei required to render crystallization possible. Overall, we regard InGeTe3 as a balanced 2D PCM with both high thermal stability and large electrical contrast for embedded memory applications. [ABSTRACT FROM AUTHOR]

Neuromorphic devices constitute a novel approach to computing that takes inspiration from the brain to unify the processing and storage units. Memories based on phase‐change materials (PCMs) are potential candidates for such devices due to their non‐volatility and excellent scalability, however their use is hindered by their conductance variability and temporal drift in resistance. Recently, it has been shown that the utilization of phase‐change heterostructures consisting of nanolayers of the Sb2Te3 PCM interleaved with a transition‐metal dichalcogenide, acting as a confinement material, strongly mitigates these problems. In this work, superlattice heterostructures made of TiTe2 and two prototypical PCMs, respectively GeTe and Ge2Sb2Te5 are considered. By performing ab initio molecular dynamics simulations, it is shown that it is possible to switch the PCMs without destroying the superlattice structure and without diffusion of the atoms of the PCM across the TiTe2 nanolayers. In particular, the model containing Ge2Sb2Te5 shows weak coupling between the two materials during the switching process, which, combined with the high stability of the amorphous state of Ge2Sb2Te5, makes it a very promising candidate for neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

Ge–Sb–Se–Te chalcogenides, namely Se-substituted Ge–Sb–Te, have been developed as an alternative optical phase change material (PCM) with a high figure-of-merit. A need for the integration of such new PCMs onto a variety of photonic platforms has necessitated the development of fabrication processes compatible with diverse material compositions as well as substrates of varying material types, shapes, and sizes. This study explores the application of chemical solution deposition as a method capable of creating conformally coated layers and delves into the resulting modifications in the structural and optical properties of Ge–Sb–Se–Te PCMs. Specifically, we detail the solution-based deposition of Ge–Sb–Se–Te layers and present a comparative analysis with those deposited via thermal evaporation. We also discuss our ongoing endeavor to improve available choice of processing-material combinations and how to realize solution-derived high figure-of-merit optical PCM layers, which will enable a new era for the development of reconfigurable photonic devices. [ABSTRACT FROM AUTHOR]

Information on the state of research on the effect of hydrogen on the superconducting properties of various compounds is presented. The review consists of an introduction, one appendix and four sections: methods for the synthesis of modern hydrogen-containing superconductors, experimental studies of the properties of hydrogen-containing superconductors, mechanisms of the influence of hydrogen on superconductivity, problems and prospects of hydrogen-containing superconductors. [ABSTRACT FROM AUTHOR]