Quaternized Research Articles

LiNbCoX (X = Al, Ga) quaternary Heusler compounds for high-temperature thermoelectric properties: a computational approach

LiNbCoX (X = Al, Ga) quaternary Heusler compounds for high-temperature thermoelectric properties: a computational approach

Design Principle for Tetrahedral Semiconductors and Their Functional Derivatives: Cation Stabilizing Charged Cluster Network

Colloidal quantum dots (QDs) of groups II-VI and III-V are key ingredients for next-generation light-emitting devices. Yet, many of them are heavy-element-containing or indirect bandgap, causing limited choice of environmental friendly efficient light-emitting materials. Herein, we resolve this issue by exploring potential derivatives of the parent semiconductors, thus expanding the material space. The key to success is the discovery of a principle for designing those materials, namely, cation stabilizing charged cluster network. Guided by this principle, three novel categories of cubic materials have been predicted, namely, porous binary compounds, I-II-VI ternary compounds, and I-II-III-V quaternary compounds. Using first-principles calculations, 65 realistic highly stable candidate materials have been theoretically screened. Their structural and compositional diversity enables a wide tunability of emitting wavelength from far-infrared to ultraviolet region. This work enriches the family of tetrahedral semiconductors and derivatives, which may be of interest for a broad field of optoelectronic applications.

9 mV/V ultra-low DIBL of suppressing SCEs in InAlN/GaN HEMT with lattice-matched InxAlyGa(1-x-y)N back-barrier for RF device

An innovative T-gate In0.17Al0.83N/GaN HEMT with the lattice-matched In0.15Al0.69GaN back-barrier is planned. Analyze and compare the DC and RF characteristics of the proposed device. A lattice-matched quaternary compound back-barrier to overcome the SCEs by modulating the energy level of the channel. The proposed HEMT exhibits excellent with the drain induced barrier lower(DIBL) of 9 mV/V, the subthreshold swing(SS) of 64 mV/dec, the off-state breakdown voltage of 55 V, the peak current density(Idmax) of 3.17 A/mm, the transconductance(gm) of 828 mS/mm, the current gain cut-off frequency(fT)/power gain cut-off frequency(fMAX) of 196/259 GHz and the JFOM figure of merit(JFOM) of 10.78 THz. The attractive DC performance, ultra-high cut-off frequency, and high RF quality factors of the device proposed in this article indicate that it has great application potential in future millimeter-wave applications.

Quantification of electronic and magnetoelastic mechanisms of first-order magnetic phase transitions from first principles: application to caloric effects in La(FeSi)13

and derived quaternary compounds are well-known for their giant, tunable, magneto- and barocaloric responses around a first-order paramagnetic-ferromagnetic transition near room temperature with low hysteresis. Remarkably, such a transition shows a large spontaneous volume change together with itinerant electron metamagnetic features. While magnetovolume effects are well-established mechanisms driving first-order transitions, purely electronic sources have a long, subtle history and remain poorly understood. Here we apply a disordered local moment picture to quantify electronic and magnetoelastic effects at finite temperature in from first-principles. We obtain results in very good agreement with experiment and demonstrate that the magnetoelastic coupling, rather than purely electronic mechanisms, drives the first-order character and causes at the same time a huge electronic entropy contribution to the caloric response.

Distributed Bragg Reflector–Mediated Excitation of InAs/InP Quantum Dots Emitting in the Telecom C‐Band

Herein, it is demonstrated that optical excitation of InAs quantum dots (QDs) embedded directly in an InP matrix can be mediated via states in a quaternary compound constituting an InP/InGaAlAs bottom distributed Bragg reflector (DBR) and native defects in the InP matrix. It does not only change the carrier relaxation in the structure but could also lead to the imbalanced occupation of QDs with charge carriers, because the band structure favors the transfer of holes. Thermal activation of carrier transfer can be observed as an increase in the emission intensity versus temperature for excitation powers below saturation on the level of both an inhomogeneously broadened QD ensemble and single QD transitions. That increase in the QD emission is accompanied by a decrease in the emission from the InGaAlAs layer at low temperatures. Finally, carrier transfer between the InGaAlAs layer of the DBR and the InAs/InP QDs is directly proven by the photoluminescence excitation spectrum of the QD ensemble. The reported carrier transfer can increase the relaxation time of carriers into the QDs and thus be detrimental to the coherence properties of single and entangled photons. It is important to take it into account while designing QD‐based devices.

Experimental observation of spin glass state in the highly disordered quaternary Heusler alloy FeRuMnGa

The realization of the spin-glass (SG) state in Heusler alloys is very rare despite the presence of inherent structural and elemental disorder in those compounds. Although a few half- and full-Heusler alloys are known to exhibit the SG state, there is hardly any manifestation of the same in cases of quaternary Heusler compounds. Here we report the observation of a SG state in a highly disordered equiatomic quaternary Heusler compound: FeRuMnGa where the SG state is in between the canonical SG and the cluster glass. Different intricate features of the SG state including nonequilibrium magnetic dynamics at low temperatures in the compound are unveiled through our comprehensive magnetic, heat capacity, and neutron-diffraction studies. The structural disorder in the sample is neither conventional $A2$- nor $B2$ -type whereas those two types are commonly observed for Heusler compounds. The presence of disorder also plays a significant role in electron transport properties of the alloy, which is reflected in its exhibition of semimetallic behavior and anomalous Hall effect at low temperatures.

Revisiting the Crystal Structure of Layered Oxychalcogenides Ln2O2S2 (Ln = La, Pr, and Nd).

La2O2S2 was recently used as a precursor to prepare either a new metastable form of La2O2S by de-insertion of half of sulfur atoms of (S2) dimers or quaternary compounds by insertion of a coinage metal (e.g., La2O2Cu2S2). A strong structural relationship exists between the polysulfide precursor and the synthesized products, which highlights the topochemical nature of these reactions. Nevertheless, the crystal structure of the precursor material is still a matter of debate. Namely, several structural models were reported so far in the literature with different space groups and/or crystal systems. All these models were built upon infinite [Ln2O2] slabs separated from each other by a flat sulfur layer of (S2) dumbbells. Nevertheless, all (S2) dimers within a given sulfur layer may rotate in phase by 90° compared to the ideal model that induces an overall atomic disorder in (S2) dimer orientation along the stacking axis. This leads to some imbroglio and much confusion in the description of structural arrangement of Ln2O2S2 materials. Herein, the crystal structures of La2O2S2 and its Pr and Nd variants are revisited. We propose an alternative model that reconciles pre-existing structural descriptions of Ln2O2S2 (Ln = La, Pr, and Nd) materials and highlights the strong dependency of the degree of long-range ordering of the sulfur layers on the synthesis conditions.

Thermo-lp: A computational tool to evaluate reaction thermodynamics for synthesizing Mn+1AXn (MAX) phases based on linear programming optimization method

Thermo-lp (Thermodynamics-Linear Programing) is a computational program written in C and Python for evaluating the thermodynamic formability of MAX phases at the finite temperature, including configurational, electronic, and vibrational entropies. The program uses the phonon density of states (PDOS) and electron density of states (EDOS) as the main inputs to obtain the Gibbs free energy in a temperature range from 0 K to 2000 K for each crystal structure in the self-contained structural and thermodynamic data pool. Thermo-lp offers a highly reliable evaluation of the overall thermodynamic stability of a target MAX phase with respect to many competing impurities using linear programing optimization algorithm. Thermo-lp program is also capable to simultaneously compose and optimize the synthetic pathways for the target MAX phase due to the implementation of constrained linear programing procedure. The capabilities of Thermo-lp program are demonstrated using the quaternary Cr2TiAlC2 o-MAX compound as the typical example by successfully predicting the thermodynamically most feasible synthetic route, and the most likely impurities at 1724 K for the annealing temperature. Program summaryProgram Title: Thermo-lpCPC Library link to program files:https://doi.org/10.17632/ykdpvcr8by.1Developer's repository link:https://gitlab.com/FxhLn/thermo-lp.gitLicensing provisions: MITProgramming language: C and PythonNature of problem: Evaluating the thermodynamic formability of a MAX phase and finding the most competing impurities associated with a specific synthetic pathway among many possible decomposition reactions requires an efficient and reliable searching algorithm within a large structural data pool.Solution method: Using phonon density of states and electron density of states as the main input data to calculate the finite-temperature corrections to Gibbs free energy. Utilizing the advanced linear programing optimization procedure to evaluate the overall thermodynamic formability of MAX phase with respect to competing impurities based on a self-built thermodynamic data pool.

Synthesis and Crystal Structure of Zr3V3GeSn4

Quantum fluctuations inherent in electronic systems positioned close to magnetic instabilities can lead to novel collective phenomena. One such material, β-Ti6Sn5, sits close to ferromagnetic (FM) instability and can be pushed to an itinerant FM-ordered state with only minute magnetic or non-magnetic doping. The binary nature of this compound, however, limits the tuning variables that can be applied to study any emergent physics, which are likely to be sensitive to the introduction of chemical disorder.Accordingly, we grew high-quality single crystals of a new quaternary compound Zr3V3GeSn4 from a Sn-rich self flux, and determined the structure with single-crystal X-ray diffraction. Zr3V3GeSn4 forms in an ordered derivative of the hexagonal β-Ti6Sn5 structure with Zr and V atomic positions that show no indication of site interchange. Ge likewise occupies a single unique atomic position. The V site, which would be the one most likely to give rise to any magnetic character, is located at the center of a distorted octahedron of Sn, with such octahedra arranged in face-sharing chains along the crystallographic c axis, while the chains themselves are organized in a kagome geometry. Zr3V3GeSn4 represents the second known quaternary phase within this system, suggesting that other compounds with this structure type await discovery.

High efficiency Cu2MnSnS4 thin film solar cells with SnS BSF and CdS ETL layers: A numerical simulation

The quaternary compound copper manganese tin sulfide Cu2MnSnS4 is a potential absorber semiconductor material for fabricating thin film solar cells (TFSC) thanks to their promising optoelectronic parameters. This article numerically investigated the performance of Cu2MnSnS4 (CMTS)-based TFSC without and with tin sulphide (SnS) back surface field (BSF) thin-film layer. First, the impact of several major influential parameters such as the active material's thickness, doping concentration of photoactive materials, density of bulk and interface defect, working temperature, and metal contact, were studied systematically without a BSF layer. Thereafter, the photovoltaic performance of the optimized pristine cell was further investigated with an SnS as BSF inserted between the absorber (CMTS) with a Platinum back metal of an optimized heterostructure of Cu/ZnO:Al/i-ZnO/n-CdS/p-Cu2MnSnS4/Pt. Thus, the photoconversion efficiency (PCE) of 25.43% with a JSC of 34.41 mA/cm2 and VOC of 0.883 V was achieved under AM1.5G solar spectrum without SnS BSF layer. Furthermore, an improved PCE of 31.4% with a JSC of 36.21 mA/cm2 and VOC of 1.07 V was achieved with a quantum efficiency of over 85% in the wavelengths of 450–1000 nm by the addition of SnS BSF layer. Thus, this obtained systematic and consistent outcomes reveal immense potential of CMTS with SnS as absorber and BSF, respectively and provide imperious guidance for fabricating highly a massive potential efficient solar cell.

Structural Studies and Thermal Analysis in the Cs2MoO4–PbMoO4 System with Elucidation of β-Cs2Pb(MoO4)2

The quaternary compound Cs2Pb(MoO4)2 was synthesized and its structure was characterized using X-ray and neutron diffraction from 298 to 773 K, while thermal expansion was studied from 298 to 723 K. The crystal structure of the high-temperature phase β-Cs2Pb(MoO4)2 was elucidated, and it was found to crystallize in the space group R3̅m (No. 166), i.e., with a palmierite structure. In addition, the oxidation state of Mo in the low-temperature phase α-Cs2Pb(MoO4)2 was studied using X-ray absorption near-edge structure spectroscopy. Phase diagram equilibrium measurements in the Cs2MoO4-PbMoO4 system were performed, revisiting a previously reported phase diagram. The equilibrium phase diagram proposed here includes a different composition of the intermediate compound in this system. The obtained data can serve as relevant information for thermodynamic modeling in view of the safety assessment of next-generation lead-cooled fast reactors.

Exploring the Effect of Kesterites and Zinc‐Based Charge Transport Materials on the Device Performance and Optoelectronic Properties of FAPbI3Perovskite Solar Cells

Formamidinium lead triiodide (FAPbI3)‐based perovskite solar cells (PSCs) have shown greater structural stability but lower power conversion efficiency (PCE) than other established perovskites. The efficiency of the PSC can be improved by identifying suitable charge transport layers for FAPbI3, having good conductivity, and wide bandgap. Kesterite materials belonging to the adamantine family of chalcogenides are quaternary compounds with high conductivity and tunable bandgap. They have shown excellent results when employed in thin films and hence have emerged as an alternate option to be used for the hole transport layers (HTL). Similarly, zinc‐based materials have remarkable properties in terms of their wide bandgap, inability to oxidize, and abundance, making them a viable option to be explored as electron transport layers (ETL). Herein, six different kesterits are used as HTL to simulate FAPbI3PSC with four different zinc‐based ETL. Henceforth, a total of 24 structures is modeled and optimized using SCAPS‐1D. The effect of these materials on the optical absorption, quantum efficiency, electric field,I–Vcharacteristics, and recombination is studied. Among all the structures, CBTS/FAPbI3/CdZnS is found to be the best‐performing PSC structure with PCE of 28.55%, short‐circuit current of 26.8 mA cm−2, open‐circuit voltage of 1.19 V, and fill factor of 88.93%.

First-principles calculations to investigate structural, elastic and thermodynamic properties of new M2ScSnC2 (M=V or Nb) quaternary compounds for 312 MAX phases

In this research, the approach of FP-LAPW (full potential linearized augmented plane wave) is employed within WIEN2K for the investigations of structural, thermodynamic, electronic, and mechanical properties of the V2ScSnC2 and Nb2ScSnC2 MAX-phases quaternary compounds. The V2ScSnC2 and Nb2ScSnC2 compounds exist in “α” and “β” polymorph structures. The formation energies (Eform) investigated insure that the α-polymorph is more stable than the β one. As it happens, Nb2ScSnC2 is more stable than V2ScSnC2. The Nb2ScSnC2 has an enhanced mechanical property compared to the V2ScSnC2 compound. The elastic constants (ECs) of interested materials fulfill all the conditions of mechanical stability and revealed a ductile nature. The predicted Cauchy's pressure and Poisson's ratio possess positive values signifying the ionic character of the V2ScSnC2 compound. The quaternary Nb2ScSnC2 compound exists as amalgamation of covalent and ionic bonds with a predominance of the ionic bonding character. The high melting temperature and high Debye temperature of V2ScSnC2 and Nb2ScSnC2 make them suitable for use in harsh environments. Furthermore, they exhibit potential as a promising material for thermal barrier coatings (TBCs). Electronic structure analysis confirm the metallic character of the two interested compounds. At high temperatures and pressures the thermodynamic properties including the Cv (Heat capacity) and ƟD(Debye temperature) are explored. We deem that this study of quaternary MAX-phase compounds will bring new insight for the experimentalists to employ for their future applications.

Application of the reference interaction site model self-consistent field method based on the Dirac-Hartree–Fock wave function to a chemical reaction

The reference interaction site model self-consistent field (RISM-SCF) method is a combined method of the electronic structure theory of molecules and the integral equation theory of molecular liquids. The RISM-SCF method based on the Dirac-Hartree-Fock wave function, recently proposed, is applied to a chemical reaction, specifically, a Menshutkin reaction in aqueous solution. The Helmholtz energy profile along the reaction coordinate is calculated and the characteristics of the reaction are discussed based on energy component analysis.

A family of flexible two-dimensional semiconductors: MgMX2Y6 (M = Ti/Zr/Hf; X = Si/Ge; Y = S/Se/Te)

Inspired by the recently predicted 2D MX2Y6 (M = metal element; X = Si/Ge/Sn; Y = S/Se/Te), we explore the possible applications of alkaline earth metal (using magnesium as example) in this family based on the idea of element replacement and valence electron balance. Herein, we report a new family of 2D quaternary compounds, namely MgMX2Y6 (M = Ti/Zr/Hf; X = Si/Ge; Y = S/Se/Te) monolayers, with superior kinetic, thermodynamic and mechanical stability. In addition, our results indicate that MgMX2Y6 monolayers are all indirect band gap semiconductors with band gap values ranging from 0.870 to 2.500 eV. Moreover, the band edges and optical properties of 2D MgMX2Y6 are suitable for constructing multifunctional optoelectronic devices. Furthermore, for comparison, the mechanical, electronic and optical properties of In2X2Y6 monolayers have been discussed in detail. The success of introducing Mg into the 2D MX2Y6 family indicates that more potential materials, such as Ca- and Sr-based 2D MX2Y6 monolayers, may be discovered in the future. Therefore, this work not only broadens the existing family of 2D semiconductors, but it also provides beneficial results for the future.

Stimulation of Aquatic Bacteria from Mammoth Cave, Kentucky, by Sublethal Concentrations of Antibiotics

Many microorganisms secrete secondary metabolites with antibiotic properties; however, there is debate whether the secretions evolved as a means to gain a competitive edge or as a chemical signal to coordinate community growth. The objective of this research was to investigate if select antibiotics acted as a weapon or as a chemical signal by exposing communities of aquatic cave bacteria to increasing concentrations of antibiotics. Water samples were collected from six cave locations where actinobacterial mats appeared to be plentiful. Bacterial growth was measured using colony counts on 10 % tryptic soy agar augmented with increasing concentrations of erythromycin, tetracycline, kanamycin, gentamicin, or quaternary ammonia compounds (QAC). Colony counts generally decreased as the gentamicin, kanamycin and QAC dose increased. In contrast, the colony numbers increased on agar plates supplemented with 0.01 mg L−1, 0.10 mg L−1 and 1.00 mg L−1 erythromycin or tetracycline. A 10.00 mg L−1 dose of each antibiotic treatment reduced bacteria colonies by 98 % or more. Community-level physiological capabilities were evaluated using Ecolog plates inoculated with cave water dosed with either 0.00 mg L−1 or 0.10 mg L−1 of erythromycin. Incubation with the antibiotic almost doubled the number of food substrates used in the first 24 hours. There was a significant increase in the use of acetyl glucosamine, arginine, and putrescine when bacteria were exposed to 0.10 mg L−1 erythromycin triggered by the antibiotic acting as a chemical messenger. Principal component analysis confirmed a shift in substrate preferences when erythromycin was added. A conceptual ecological model is proposed based on the response of aquatic cave bacteria to sublethal antibiotics.

Recent Advances in Electron Donor‐Acceptor (EDA)‐Complex Reactions involving Quaternary Pyridinium Derivatives

AbstractQuaternary pyridinium compounds are valuable intermediates in organic synthesis, which have gained immense popularity in the synthetic community. The application of transition metal or photoredox catalysis in transforming quaternary pyridinium compounds into various C−C and C−X bonds is well established. A majority of these methods require high temperatures, expansive catalysts, and delicate conditions for successful execution. On the other hand, the use of transition metal‐free and photocatalysis‐free strategies in constructing C−C and C−X bonds using quaternary pyridinium derivatives has been sought‐after. In this context, the electron‐donor‐acceptor (EDA)‐complex reactions have emerged as a state‐of‐the‐art organic synthetic methodology, which do not require any photocatalyst for their successful execution. EDA‐complex photochemistry takes advantage of the electron‐acceptor ability of quaternary pyridinium derivatives, which can quickly generate a radical precursor via the deaminative process. These newly generated radical intermediates are useful in several valuable transformations. We hereby, in this review, discuss an area of major progress in EDA‐complex mediated reactions involving quaternary pyridinium compounds with mechanism, substrate scope, and limitations.magnified image

Surface engineering of colloidal quaternary chalcogenide Cu2ZnSnS4 nanocrystals: a potential low-cost photocatalyst for water remediation.

Colloidal route synthesis of quaternary compound CZTS (Cu2ZnSnS4) has been anticipated with an inimitable combination of coordinating ligands and solvents using the hot injection technique. CZTS is recognized as one of the worthiest materials for photo-voltaic/catalytic applications due to its exclusive properties (viz., non-toxic, economical, direct bandgap, high absorbance coefficient, etc.). This paper demonstrates the formation of crystalline, single-phased, monodispersed, and electrically passivated CZTS nanoparticles using a distinctive combination of ligands viz. oleic acid (OA)-trioctylphosphine (TOP) and butylamine (BA)-trioctylphosphine (TOP). Detailed optical, structural, and electrochemical studies were done for all CZTS nanoparticles, and the most efficient composition was found using ligands butylamine and TOP. CZTS nanocrystals were rendered hydrophilic via surface-ligand engineering, which was used for photocatalysis studies of organic pollutants. Malachite green (MG) and rhodamine 6G (Rh) for water remediation have great commercial prospects. The unique selling proposition of this work is the rapid synthesis time (~ 45min) of colloidal CZTS nanocrystals, cost-effective ligand-exchange process, and negligible material wastage (~ 200µl per 10ml of pollutant) during photocatalytic experiments.

Pholcodine exposure increases the risk of perioperative anaphylaxis to neuromuscular blocking agents: the ALPHO case-control study

BackgroundNeuromuscular blocking agents (NMBAs) are among the leading cause of perioperative anaphylaxis, and most of these reactions are IgE mediated. Allergic sensitisation induced by environmental exposure to other quaternary ammonium-containing compounds, such as pholcodine, has been suggested. The aim of this study was to assess the relationship between pholcodine exposure and NMBA-related anaphylaxis. MethodsALPHO was a multicentre case-control study, comparing pholcodine exposure within a year before anaesthesia between patients with NMBA-related perioperative anaphylaxis (cases) and control patients with uneventful anaesthesia in France. Each case was matched to two controls by age, sex, type of NMBA, geographic area, and season. Pholcodine exposure was assessed by a self-administered questionnaire and pharmaceutical history retrieved from pharmacy records. The diagnostic values of anti-pholcodine and anti-quaternary ammonium specific IgE (sIgE) were also evaluated. ResultsOverall, 167 cases were matched with 334 controls. NMBA-related anaphylaxis was significantly associated with pholcodine consumption (odds ratio 4.2; 95% confidence interval 2.3–7.0) and occupational exposure to quaternary ammonium compounds (odds ratio 6.1; 95% confidence interval 2.7–13.6), suggesting that apart from pholcodine, other environmental factors can also lead to sensitisation to NMBAs. Pholcodine and quaternary ammonium sIgEs had a high negative predictive value (99.9%) but a very low positive predictive value (<3%) for identifying NMBA-related reactions. ConclusionsPatients exposed to pholcodine 12 months before NMBA exposure have a significantly higher risk of an NMBA-related anaphylaxis. The low positive predictive values of pholcodine and quaternary ammonium sIgEs precludes their use to identify a population with a high risk of NMBA-related anaphylaxis. Clinical trial registrationNCT02250729.

Crystal growth, exfoliation, and magnetic properties of quaternary quasi-two-dimensional CuCrP2S6

We report optimized crystal growth conditions for the quaternary compound ${\mathrm{CuCrP}}_{2}{\mathrm{S}}_{6}$ by chemical vapor transport. Compositional and structural characterization of the obtained crystals were carried out by means of energy-dispersive x-ray spectroscopy and powder x-ray diffraction. ${\mathrm{CuCrP}}_{2}{\mathrm{S}}_{6}$ is structurally closely related to the ${M}_{2}{\mathrm{P}}_{2}{\mathrm{S}}_{6}$ family ($M$: transition metal), which contains several compounds that are under investigation as 2D magnets. As-grown crystals exhibit a platelike, layered morphology as well as a hexagonal habitus. We present successful exfoliation of such as-grown crystals down to thicknesses of 2.6 nm corresponding to four layers. ${\mathrm{CuCrP}}_{2}{\mathrm{S}}_{6}$ crystallizes in the monoclinic space group $C2/c$. Magnetization measurements reveal an antiferromagnetic ground state with ${T}_{\text{N}}\ensuremath{\approx}30$ K and a positive Curie-Weiss temperature in agreement with dominant ferromagnetic intralayer coupling. Specific heat measurements confirm this magnetic phase transition and the magnetic order is suppressed in an external magnetic field of about 6 T (8 T) applied parallel (perpendicular) to the $ab$ plane. At higher temperatures between 140--200 K, additional broad anomalies associated with structural changes accompanying antiferroelectric ordering are detected in our specific heat studies.