Ternary Analogs Research Articles

Homoatomic Polychalcogenide Nonlinear Optical Anionic Groups with Ultra-Large Optical Anisotropy.

Functional assembly of nonlinear optical (NLO) motifs with a large optical anisotropy is vital to the development of advanced NLO and birefringent materials. In this work, we highlight that, in addition to heteroatomic NLO motifs, homoatomic anionic clusters formed by aggregated anions (S, Se, Te) exhibit diverse chain-, ring-, and cage-like chemical structures as well as one-, two-, and three-dimensional motif alignments. The rich structural chemistry enables homoatomic polychalcogenides (HAPCs) to exhibit asymmetric structural features and anisotropic optical properties, with great potential for NLO and birefringent performance. Focusing on totally 55 binary HAPCs A2Qn (n = 2, 3, 4, 5; A = Na, K, Rb, Cs; Q = S, Se, Te) and their ternary analogues, we employ the state-of-the-art first-principles approach to systematically investigate the modulation evolution of their NLO and birefringent properties. Remarkably, Rb2Te3 and Na2TeSe2 exhibit rarely colossal birefringence (>1.0@10 μm) and NLO effects (>20 × AgGaS2), much larger than conventional NLO chalcogenides. Na2Te3 presents the largest birefringence to date (∼3.48@1, 2.72@2, 2.34@10 μm), indicating the unique structural superiority of HAPC in terms of ultra-large birefringence. By mining the intrinsic mechanism, the HAPC anionic groups are identified as novel mid-infrared NLO "material genes", furnishing unique NLO and birefringent performance for the design of novel optoelectronic materials.

A survey on association schemes on triples

Association schemes on triples (ASTs) are ternary analogues of classical association schemes, whose relations and adjacency algebras are ternary instead of binary. We provide a survey of the current progress in the study of ASTs, highlighting open questions, suggesting research directions, and producing some related results. We review properties of the ternary adjacency algebras of ASTs, ASTs whose relations are invariant under some group action, and ASTs obtained from 2-designs and two-graphs. We also provide a notion of fusion and fission ASTs, using the AST obtained from the affine special linear group A S L (2, q ) as an example.

A note on Assmus–Mattson type theorems

In the present paper, we give Assmus–Mattson type theorems for codes and lattices. We show that a binary doubly even self-dual code of length 24m with minimum weight 4m provides a combinatorial 1-design and an even unimodular lattice of rank 24m with minimum norm 2m provides a spherical 3-design. We remark that some of such codes and lattices give t-designs for higher t. As a corollary, we give some restrictions on the weight enumerators of binary doubly even self-dual codes of length 24m with minimum weight 4m. Ternary and quaternary analogues are also given.

Material and device properties of Si-based Cu0.5Ag0.5InSe2 thin-film heterojunction diode

Cu0.5Ag0.5InSe2 (CAIS) thin films were deposited on a glass substrate by sequential sputtering of Cu, Ag, and In2Se3-stacked film layers. Structural characterization showed that the deposited CAIS film satisfies nearly the stoichiometric form with uniform and homogeneous surface structure. The single-phase polycrystalline behavior without any secondary-phase formation was observed from the diffraction profile. The optical properties were investigated using temperature-dependent transmission measurements in the wavelength region of 600–1100 nm and in between 10 and 300 K. In the region of interest, the transmission spectra shifted towards the higher wavelengths as a result of an increase in the sample temperature. The analysis of the absorption data based on the transmission spectra resulted in absorption coefficient values of around 105 cm−1 and the presence of direct allowed optical transition. From the Tauc plots, CAIS samples were found to have three distinct direct optical transitions depending on the possible splitting in the valence band. The obtained room temperature uppermost band gap energy value of 1.09 eV was found in the energy limit of ternary analogues (CuInSe2 and AgInSe2), and also in a good agreement with the previous works in the literature. The dependency of the band gap energy on the temperature was analyzed using fundamental relations. In addition, the electrical characteristics of the film layer were discussed in four-contact conductivity measurements, and room temperature conductivity was observed as 0.8 Ω−1 cm−1. Additionally, two activation energy values were found in the temperature-dependent conductivity profile. As a diode application, CAIS/Si heterojunction was fabricated and the main diode parameters were extracted at dark and room temperature conditions.

Physicochemical Aspects of Development of Multicomponent Chalcogenide Phases Having the Tl5Te3 Structure: A Review

The literature data on ternary structural analogues of the compound Tl5Te3 and multicomponent phases based on them are systematized. This class of inorganic substances is of considerable scientific and practical interest as promising functional materials having thermoelectric, optical, and magnetic properties, as well as topologically protected surface states and superconductivity. The focus of the survey is on phase equilibria in ternary and more complex systems where structural analogues of Tl5Te3 are formed. Crystalstructure features, thermodynamic and some physical properties of these compounds and phases of variable composition are considered.

High efficiency oxygen evolution reaction enabled by 3D network composed of nitrogen-doped graphitic carbon-coated metal/metal oxide heterojunctions

The ability to develop low-cost highly efficient electrocatalyst for oxygen evolution reaction (OER) is key to the overall water splitting device that represents a viable and promising source of alternative energy. Herein, we crafted three-dimensional (3D) network comprising nitrogen-doped graphitic carbon-coated heterojunctions (denoted NC-Ni0.36Fe0.64/MnOx) via one-step calcination of hybrid precursors containing ternary Prussian blue analogues and polymers. The NC-Ni0.36Fe0.64/MnOx nanocomposites were then exploited as catalysts for OER, displaying exceptional performance with a small overpotential of 300 mV to reach 10 mA cm−2, a low Tafel slope of 43 mV/dec and an outstanding stability without deactivation over a 10-h OER. Notably, compared to commercial RuO2 catalysts, NCNi0.36Fe0.64/MnOx catalysts demonstrated much lower overpotential and Tafel slope. The excellent OER performance can be attributed to the presence of high-valence oxidized metal species (Ni2+, Fe2+ and Mn2+) at the heterostructured interface as well as pyridinic N-doped carbon species on highly conductive graphitic carbon network, thus greatly facilitating the electron-withdrawing from OH− and thus charge transfer during OER. This simple yet effective strategy may open new possibilities for creating a wide range of low-cost, high-efficiency, non-precious transition metal OER catalysts for the overall water splitting.

The Gaseous Phase as a Probe of the Astrophysical Solid Phase Chemistry

Abstract In support of space missions and spectroscopic observations, laboratory experiments on ice analogs enable a better understanding of organic matter formation and evolution in astrophysical environments. Herein, we report the monitoring of the gaseous phase of processed astrophysical ice analogs to determine if the gaseous phase can elucidate the chemical mechanisms and dominant reaction pathways occurring in the solid ice subjected to vacuum ultra-violet (VUV) irradiation at low temperature and subsequently warmed. Simple (CH3OH), binary (H2O:CH3OH, CH3OH:NH3), and ternary ice analogs (H2O:CH3OH:NH3) were VUV-processed and warmed. The evolution of volatile organic compounds in the gaseous phase shows a direct link between their relative abundances in the gaseous phase, and the radical and thermal chemistries modifying the initial ice composition. The correlation between the gaseous and solid phases may play a crucial role in deciphering the organic composition of astrophysical objects. As an example, possible solid compositions of the comet Lovejoy are suggested using the abundances of organics in its comae.

Pyrite-Type Nanomaterials for Advanced Electrocatalysis.

Since being proposed by John Bockris in 1970, hydrogen economy has emerged as a very promising alternative to the current hydrocarbon economy. Access to reliable and affordable hydrogen economy, however, requires cost-effective and highly efficient electrocatalytic materials that replace noble metals (e.g., Pt, Ir, Ru) to negotiate electrode processes such as oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). Although substantial advances in the development of inexpensive catalysts, successful deployment of these materials in fuel cells and electrolyzers will depend on their improved activity and robustness. Recent research has demonstrated that the nanostructuring of Earth-abundant minerals provides access to newly advanced energy materials, particularly for nanostructured pyrites, which are attracting great interest. Crystalline pyrites commonly contain the characteristic dianion units and have cations occurring in octahedral coordination-whose generalized formula is MX2, where M can be transition metal of groups 8-12 and X is a chalcogen. The diversity of pyrites that are accessible and their versatile and tunable properties make them attractive for a wide range of applications from photovoltaics to energy storage and electrocatalysis. Pyrite-type structures can be further extended to their ternary analogues, for example, CoAsS (cobaltite), NiAsS (gersdorffite), NiSbS (ullmannite), CoPS, and many others. Moreover, improved properties of pyrites can be realized through grafting them with promoter objects (e.g., metal oxides, metal chalcogenides, noble metals, and carbons), which bring favorable interfaces and structural and electronic modulations, thus leading to performance gains. In recent years, research on the synthesis of pyrite nanomaterials and on related structure understanding has dramatically advanced their applications, which offers new perspectives in the search for efficient and robust electrocatalysts, yet a focused review that concentrates the critical developments is still missing. In this Account, we describe our recent progress on the discoveries and applications of nanostructured pyrite-type materials in the area of electrocatalysis. We first briefly highlight some interesting properties of pyrite-type materials and why they are attractive for modern electrocatalysis. Some recent advances on their synthesis that allows access to highly nanostructured pyrite-type materials are reviewed, along with the grafting of resultant pyrites with foreign materials (e.g., metal oxides, metal chalcogenides, noble metals, and carbons) to enable improved catalytic performances. We finally spotlight the exciting examples where pyrite nanostructures were used as efficient electrocatalysts to drive the OER, HER, and methanol-tolerant ORR. It is reasonable to assume that, with significant efforts and focus, the next few years will bring new advances on the pyrites and other minerals for electrocatalysis.

Fabrication, characterization, and visible-light photocatalytic performance of ternary plasmonic composites

A group of mesoporous WO3-TiO2-contained SBA15 composites (W-Ti-SBA15) and their Ag-contained plasmonic analogs were fabricated and then systematically characterized by a collection of analytical techniques. Original mesoporous structures with highly ordered channels were well-maintained and WO3-TiO2 could form spherical clusters that were gradually reduced in size accompanying with the decrease of TiO2/SiO2 mass ratios. Deposited Ag species were confirmed as zero-valence Ag by X-ray photoelectron spectroscopy analysis and exerted almost no effect on the morphology, microstructure, and textural but optical property, by which the visible-light harvesting ability of composites was remarkably strengthened owing to the localized surface plasmonic resonance (LSPR) induced by the metallic Ag. Under visible-light irradiation, W-Ti-SBA15 composites showed satisfactory photocatalytic performance that could be further enhanced by using their Ag-contained ternary plasmonic analogs. The enhancement of photocatalytic efficiency was mainly attributed to the favorable mesoporous morphology, the suitable band alignment, and the LSPR effect. Eventually, a possible photocatalysis mechanism was primarily proposed on the base of reactive radical species trapping experiments.

Characteristics of Australian brown coal fly ash blended geopolymers

The present study evaluates the potential re-use options for a suite of low rank brown coal fly ashes (ASTM class C fly ash) as feedstock for geopolymer binder synthesis. Ash suitability was evaluated using a number of conventional characterisation tools including XRF, calorimetric and microscopy to analyse solid phase distribution in relation to compositional differences derived from ternary diagram analogues. Blends of brown coal ash with selected black coal fly ash (class F) and blast furnace slag were developed for compressive strength and durability tests. The study show that brown coal fly ash with higher Al content improved the rate of reaction of blended binders and that observed high contents of sulphate and magnesium oxides available in some brown coal fly ashes induced accelerated decomposition in high moist environments. Overall, it was evident from both microscopy and mineralogical analysis of binder mixtures that brown coal fly ash participate in geopolymer network formation rather than act as filler material. Factors influencing brown coal ash reactivity and the potential for incorporating this class of ash in developing stable and usable geopolymer binder systems are discussed.

Structural, Optical and Photoelectrical Properties of AgInSe2 Films

The I–III–VI2 compounds are the ternary analogues of II–VI compounds. AgInSe2 is a ternary analogue of CdSe, which has been used for a number of electronic devices. AgInSe2 is a semiconductor with energy gap of 1.20 eV. They crystallize in the chalcopyrite structure, which is closely related to zinc blend structure. In the present work we employ the pulse electrodeposition technique for the first time to deposit AgInSe2 films and study their properties.AgInSe2 films were deposited by the pulse electrodepsoition technique at room temperature from a bath containing Analar grade 10 mM silversulphate, 50 mM Indium sulphate and 5 mM SeO2 at deposition potential of – 0.98V (SCE). Tin oxide coated glass substrates (5.0 ohms/ sq) were used. The duty cycle was varied in the range of 6 – 50 %. Thickness of the films measured by surface profilometer increased from 500 nm to 1000 nm as the duty cycle increased from 6 % to 50 %. Structural, optical and photoconductivity studies were made on the films.The films deposited at different duty cycles were characterized by the X-ray diffraction (XRD) pattern. All the reflections could be indexed as the tetragonal phase of AgInSe2 with the lattice parameters a = 6.09Å , c = 11:67Å , which were very close to the reported data (JCPDS Cards, 35– 1099). As the duty cycle increased, the intensity of the peaks increased. The height of the peak increased with duty cycle and the width of the peaks decreased with increase of duty cycle. No characteristic peaks of other impurities, such as Ag2Se or In2Se3, were detected in the pattern. The crystallite size was determined from Scherrer’s equation varied from 10 to 40 nm with increase of duty cycle.Energy dispersive X-ray (EDAX) spectrum gives the elemental composition of the as prepared samples. It contains 29.29% of Ag, 20.76% of In and 49.95% Se. This indicates that the as prepared films were indium deficient. The indium sites can be occupied by Ag atoms, acting as donors.The transmittance spectra at RT of AgInSe2 thin films deposited at different duty cycles exhibited interference fringes. Refractive index was calculated by envelope method and it increased from 1.25 to 1.80 with increase of wavelength from 500 nm to 1200 nm. The extinction coefficient 0.8 to 0.4 with increase of wavelength in the above range. This result is similar to that observed earlier. Photon energy vs. (αhν)2 plot of AgInSe2 thin films deposited at different duty cycles, indicated a band gap of 1.172 eVPhotoelectrochemical cell studies were made using 1M polysulphide (1M S, 1 M Na2S, 1 M NaOH) as the redox electrolyte. Graphite was used as the counter electrode. The as deposited films exhibited very poor photo output after post annealing in argon atmosphere photo output was observed. For a film deposited at 50 % duty cycle, an open circuit voltage of 0.45 V and a short circuit current density of 4.0 mA cm-2 at 60 mW cm-2 illumination was observed. Both photocurrent and photovoltage are found to increase up to 80 s photoetch, beyond which they begin to decrease. Photoetching leads to selective attack of surface states not accessible to chemical etchants. The power output characteristics after 80s photoetching indicates a Voc of 0.60V, Jsc of 7.50 mA cm-2, ff of 0.53 and h of 3.0% for 80 mWcm-2 illumination.The results of this investigation clearly points to the possibility of depositing single phase AgInSe2 films with grain size in the range of 10 – 40 nm which exhibit reasonable output when used as photoelectrodes.

Highly luminescent water-soluble quaternary Zn–Ag–In–S quantum dots and their unique precursor S/In ratio-dependent spectral shifts

Quaternary I–II–III–VI semiconductor quantum dots (QDs) containing less toxic elements are receiving increasing attention because of their promising applications in solar cells, light-emitting diode (LED), and biological labeling. Despite its advantages, the quaternary system is more complex than the binary and ternary analogues. This is reflected in the difficulty to control the size, size distribution, elemental composition, and optical properties of quaternary I–II–III–VI QDs, especially in aqueous medium. In this work, we have synthesized new aqueous quaternary Zn–Ag–In–S (ZAIS) QDs with tunable photoluminescence (PL) for the first time, giving the highest PL quantum yield (QY) of 30%, which is close to those of the conventional well-developed aqueous II–VI QDs. Most importantly, three unique spectral shifts depending on precursor S/In ratio were observed in this quaternary system. The spectral were characterized by diverse analytical methods to systematically establish distinct features of the quaternary nanomaterials. The results demonstrate the potential utility of this new water-soluble system in fundamental and applied researches with quaternary QDs.

Band Gap Engineering in Bulk and Nano Semiconductors

ABSTRACTThe changes are brought in the elemental semiconductors Si and Ge by replacing them with II-VI and III-V binary analogs or their ternary analogs I-III-VI2 chalcopyrides and II-IV-V2 pnictides respectively. Such compounds exhibit transitions from their parent compound in terms of nature of band gaps (Eg) as indirect to direct in addition to the changes in the values of the Eg. These changes have direct consequence in their optical properties with degenerate states being lifted leading to crystal field splitting and so on. The Eg in ternary bulk semiconducting materials is engineered as a function of certain structural parameters such as anion position parameter (u), tetragonal compression parameter (η) through effective alloying. The contributions to Eg due to these effects are studied as band gap anomalies. The present paper discusses the results of the band gap engineering in some of the bulk ABC2(A= Cd; B=Si,Ge,Sn; C= P,As) semiconductors using theoretical methods. The influence of each of A, B and C atom is also discussed. The dependence of morphology of nano semiconducting particles and the band gap on the chemical environment, temperature is reported by us. The confinement energy of a compound which is the difference in energy between the bulk and nano forms is investigated.

Phase equilibria and properties of solid solutions in the Tl5Te3-Tl9BiTe6-Tl5Te2I system

Phase equilibria in the Tl5Te3-Tl9BiTe6-Tl5Te2I system, containing ternary structural analogs of Tl5Te3, have been studied by differential thermal analysis, X-ray diffraction, microhardness tests, and emf measurements using concentration cells with a thallium electrode. A number of T-x sections, the 760- and 800-K sections, and the liquidus and solidus projections of the phase diagram are constructed, and the composition dependences of lattice parameters, microhardness, and emf are obtained. The results demonstrate that, despite the presence of a liquid-liquid miscibility gap, the system contains a continuous series of solid solutions isostructural with Tl5Te3.

Advanced Si-based Semiconductors for Energy and Photonic Applications

Group-IV semiconductors, including alloys incorporating Sn, have been grown on dimensionally dissimilar Si substrates using novel molecular hydride chemistries with tunable reactivities that enable low temperature, CMOS compatible integration via engineering of the interface microstructure. Here we focus on properties of three such Ge-based systems including: (1) device quality Ge layers with thicknesses >5m possessing dislocation densities <105/cm2 are formed using molecular mixtures of Ge2H6 and highly reactive (GeH3)2CH2 organometallic additives circumventing the classical Stranski-Krastanov growth mechanism, (2) metastable GeSn alloys are grown on Si via reactions of Ge2H6 and SnD4, and (3) ternary SiGeSn analogs are produced lattice-matched to Ge-buffered Si using admixtures of SiGeH6, SiGe2H8, SnD4, Ge2H6, and Si3H8. Optical experiments and prototype device fabrication demonstrate that the ternary SiGeSn system represents the first group-IV alloy with a tunable electronic structure at fixed lattice constant, effectively decoupling band gap and strain and eliminating the most important limitation in device designs based on group-IV materials. Doping at levels higher than 1019 cm-3 (both p and n-type) is achieved for all the above semiconductor systems using a similar precursor chemistry approach. Electrical and infrared optical experiments demonstrate that doped GeSn and SiGeSn have mobilities that compare or exceed that of bulk Ge. The potential applications of these materials, including micro- and optoelectronics as well as photovoltaics and thermoelectricity, are discussed.

Quaternary semiconductors with positive crystal field splitting: Potential high-efficiency spin-polarized electron sources

Traditional high efficiency spin-polarized electron sources (SPES) consist mainly of binary or pseudobinary zinc-blende GaAs based materials, whereas their ternary analogs II-IV-V2 (II=Zn, Cd, IV=Si, Ge, Sn, and V=As) as well as II-VI ternary analogs I-III-VI2 (I=Cu, Ag, III=Al, Ga, In, and VI=Se) have not drawn wide attention because their crystal field splitting ΔCF near the valence band maximum is either negative or close to zero in their ground state chalcopyrite structure. Using first-principles calculations, we show that some derivative quaternary I-III-II2-VI4 and II-IV-III2-V4 compounds can have coherent ground state stannite or kesterite structures with large and positive ΔCF due to their increased chemical and structural flexibility. We propose that ZnSiAl2As4 and CdGeAl2As4 in the stannite structure, and ZnSnGa2As4 and CuAlCd2Se4 in the kesterite structure could be good candidate SPES materials with high polarization and quantum efficiency.

New thallium neodymium tellurides

The phase equilibria in the composition region Tl2Te-Tl2Te3-Nd2Te3-NdTe of the Tl-Nd-Te system have been studied by differential thermal analysis and x-ray diffraction, and the 500-K section of its phase diagram has been mapped out. The ternary compounds identified are Tl9NdTe6, Tl4NdTe3, Tl6Nd4Te9, Tl4Nd6Te11, Tl2NdTe3, TlNdTe3, and TlNd3Te6. X-ray powder diffraction data indicate that the compounds Tl9NdTe6 and Tl4NdTe3 are structural analogs of Tl5Te3 and have tetragonal cell parameters a = 8.855 A, c = 13.010 A and a = 8.858 A, c = 12.998 A, respectively (sp. gr. I4/mcm, Z = 4). Tl9NdTe6 and Tl4NdTe3 are phases of variable composition (δ-phase), and their fields cover most of the Tl2Te-Tl5Te3-Tl4NdTe3 composition triangle. The structure of Tl5Te3 and its ternary analogs is discussed, and the conclusion is drawn that, in spite of the broad field of the δ-phase, Tl9NdTe6 and Tl4NdTe3 are daltonides, i.e., distinct chemical compounds.

Effect of Ternary Additions on the Stability of Ordered Phases in Ni-Mo Alloys—Transmission Electron Microscopy Results and First Principles Calculations

The ordering behavior of a Ni-Mo alloy in the presence of ternary additives X (X = Al, Cr, Mn, V) has been studied using transmission electron microscopy (TEM) as well as first-principles calculations using the tight-binding–linear muffin tin orbital (TB-LMTO) method. The sequence of ordering transformations in binary Ni-Mo alloys has been shown earlier to be controlled by a competition between several fcc-based superlattices, viz. Ni2Mo (Pt2Mo type), Ni3Mo (D022), Ni4Mo (D1a), and the so-called short-range ordered (SRO) structure characterized by the presence of {1½0} reflections. These ternary additives have been observed to stabilize the Ni3Mo (D022) phase compared to the Ni2Mo + Ni4Mo phase mixture, leading to a sequence of transformation different from that obtained in binary alloys. The calculated energies of formation were observed to conform to the experimentally observed stability hierarchy in these binary intermetallics and their ternary analogues. The third element stabilizes the D022 structure by contributing to the covalent component of bonding in these compounds.

Ternary analogues of Lie and Malcev algebras

We consider two analogues of associativity for ternary algebras: total and partial associativity. Using the corresponding ternary associators, we define ternary analogues of alternative and assosymmetric algebras. On any ternary algebra the alternating sum [ a, b, c] = abc − acb − bac + bca + cab − cba (the ternary analogue of the Lie bracket) defines a structure of an anticommutative ternary algebra. We determine the polynomial identities of degree ⩽7 satisfied by this operation in totally and partially associative, alternative, and assosymmetric ternary algebras. These identities define varieties of ternary algebras which can be regarded as ternary analogues of Lie and Malcev algebras. Our methods involve computational linear algebra based on the representation theory of the symmetric group.

Phase transformation in the system TlBi(Te1‐xSex)2

AbstractTlBiTe2 and TlBiSe2 ‐ that are ternary analogs of the IV‐VI semiconductors ‐, although they crystallize in the same space group R$ \bar 3 $m (D53d), exhibit different behaviour during heating. The observed phase transformation depends on Se content (x) in the system TlBi(Te1‐xSex)2 and the transformation disappears by increasing Se content after a certain value (x = 0.25). This dependence is examined through the analysis of the DSC non‐isothermal measurements and an attempt for the explanation of the observed behaviour is undertaken through the consideration of off‐center atoms. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)