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The ternary compound Hf2B2Ir5 was assessed as an electrocatalyst for the oxygen evolution reaction (OER) in 0.1 M H2SO4 . The oxidative environment restructures the studied material in the near-surface region, creating cavities in which agglomerates of IrOx(OH)y(SO4)z particles are incorporated. These in situ generated particles result from the oxidation of secondary phases in the matrix as well as from self-controlled near-surface oxidation of the ternary compound itself. The oxidation is controlled by the structural and chemical bonding features of Hf2B2Ir5. The cage-like motif, exhibiting mostly ionic interactions between positively charged Hf atoms and a covalently bonded Ir–B network, selectively controls the extent and kinetics of the transformation process induced during the operation of the electrocatalyst. The resulting self-optimized composite material, formed by a Hf2B2Ir5 matrix surrounding IrOx(OH)y(SO4)z particles, was used in the OER over 240 h at 100 mA cm-2 current density. The chemical changes, as well as the OER performance, were studied via a combination of bulk- and surface-sensitive experimental techniques as well as by employing a quantum-chemical bonding analysis.

We report here on the discovery of the superconductivity of a new ternary compound LaRh2Ga2, which possesses a CaBe2Ge2-type structure. Electrical resistivity and magnetic susceptibility measurements reveal that LaRh2Ga2 undergoes a superconducting transition at 3.7 K and exhibits type-II superconductivity. The T-linear behavior of the upper critical field is likely induced by the two-gap superconducting state because of its structural features (i.e., its noncentrosymmetric structure). A transition at Tc of specific heat suggested that the LaRh2Ga2 is a weak electron-phonon-mediated superconductor. Comparison with a related superconductor demonstrates that there is an important factor other than electron-phonon coupling strength that induces higher Tc in the LaTM2Ga2 system with a noncentrosymmetric CaBe2Ge2-type structure.

Single crystals of a novel Na-Pt-Si ternary compound, Na3Pt10Si5, were synthesized by heating the constituent elements at 1423 K. It crystallizes in a non-centrosymmetric trigonal structure of space group R32 (Z = 3) with lattice constants of a = 10.1536(3) A and c = 10.1539(3) A at 300 K. The structure consists of a three-dimensional framework made of Pt and Si atoms, and the Na atoms are contained in the tunnels of the framework. The large magnitude and the temperature dependence of the atomic displacement parameter of the Na site reveal a large thermal vibration indicative of a "rattling" motion of Na atoms in the oversized tunnel. The electronic structure calculations explain the observed metallic properties on the basis of the covalent bonds between the Pt and Si atoms in the framework and the ionic bonding of the Na atoms to the framework. A type II superconductivity with a transition temperature of 2.9 K and an upper critical field of 2.5 kOe are observed for a polycrystalline sintered bulk sample of Na3Pt10Si5 prepared by heating at 1353 K in Na vapor. Heat capacity measurements reveal a strong coupling superconductivity that is probably caused by an electron-phonon interaction enhanced by the rattling motion of the Na atoms.

Copper indium diselenide (CuInSe2) is a prototype ternary compound and group I–III–VI semiconductor with useful optoelectronic properties. CuInSe2 nanocrystals have been of significant interest because of their size-tunable optical properties and lack of toxic heavy metals. Because of the particular vacancy and antisite substitutional point defects in CuInSe2, large stoichiometric deviations can be tolerated, sometimes leading to the so-called ordered vacancy compounds (OVCs). Here, we use Raman spectroscopy of oleylamine-capped CuInSe2 nanocrystals and ab initio lattice dynamics modeling to study the concentration and arrangements of (2vCu– + InCu2+) defect pairs in the nanocrystals. The nanocrystals have randomly distributed defect pairs that become mobile under light excitation and accumulate, as in OVCs, along the [100] direction. Because the high concentration of vacancies in CuInSe2 nanocrystals is compensated by InCu2+ antisite defects, these nanocrystals do not exhibit an optical plasmon resonance...

In this work, we introduce the growth of a new complex oxide lead oxy-chalcogenide (PbOxSe1–x) thin film using an oxygen plasma-assisted molecular beam epitaxy method. Freshly cleaved BaF2(111) wafers were used as the substrates for this growth study. Systematic characterization of X-ray diffraction peaks, Raman shifts, absorption spectra, scanning electron microscopic imaging, and Hall measurements were conducted to elucidate the structural, optical, and electric properties of the as-grown PbOxSe1–x thin films. Specifically, X-ray diffraction measurements revealed that PbOxSe1–x films maintained the same rock-salt crystal structure as the PbSe semiconductor, but a slight shift in the lattice parameter was observed. A blue shift in the optical absorption edge also suggests that the inclusion of oxygen atoms led to the formation of a ternary compound crystal structure. Furthermore, all PbOxSe1–x thin films were observed to be polycrystalline in nature and displayed preferred [100] orientated grains. Slight...

A new ternary compound Cu3ZnSb was synthesized by high temperature solid state synthesis and characterized by single crystal X-ray diffraction and energy dispersive X-ray analysis. The ternary Cu3ZnSb crystallizes in the tetragonal crystal system with the space group P4/nmm (129), and its unit cell contains 10 atoms which are distributed over 4 independent crystallographic positions. The structure is built up with [Cu3Sb] slabs that correspond to the unit cells of Cu2Sb and planar 44 nets of Zn atoms. The planar nets of Zn atoms are interspersed between two adjacent [Cu3Sb] slabs. The structure can be viewed as alternating units of Cu2Sb and CsCl type β′-brass (CuZn) structures in the [001]. An unusual atomic ordering of two neighboring transition metals Cu and Zn is observed and is confirmed by first principle calculations. The atomic ordering of Cu and Zn is retained from binary β′-brass structure (CuZn) to ternary Cu3ZnSb. Total energy calculations confirmed the experimental model of Cu/Zn ordering to ...

In this work, we present a novel small molecule based on dithienylthienothiadiazole units (named SM1) acting as an efficient component in ternary blend organic solar cells to modify the hole extraction at the interface. Our findings show that the SM1 suppresses the surface recombination and enhances the open-circuit voltage ( V

Cation exchange mediated synthesis of nanoheterostructures (NHSs), core–shell structure or segmented nanostructures are gaining high interest in nanoscience research as the process gives a wide win...

We report a nonequilibrium fabrication method of n-type CoSb2.85Te0.15 skutterudites using selective laser melting (SLM) technology. A powder of CoSb2.85Te0.15 was prepared by self-propagating high-temperature synthesis (SHS) and served as the raw material for the SLM process. The effect of SLM processing parameters such as the laser power and scanning speed on the quality of the forming CoSb2.85Te0.15 thin layers was systematically analyzed, and the optimal processing window for SLM was determined. A brief postannealing at 450 °C for 4 h, following the SLM process, has resulted in a phase-pure CoSb2.85Te0.15 bulk material deposited on a Ti substrate. The Seebeck coefficient of the annealed SLM prepared bulk material is close to that of the sample prepared by the traditional sintering method, and its maximum ZT value reached 0.56 at 823 K. Moreover, a Ti–Co–Sb ternary compound transition layer of about 70 μm in thickness was found at a dense interface between CoSb2.85Te0.15 and the Ti substrate. The conta...

We report the synthesis and properties of a new layered tetragonal ternary compound CsMn4As3 (structure type, KCu4S3; space group, P4/mmm, no. 123; and Z = 2). The material is a small band gap semi...

A combination of theoretical calculation and the experimental synthesis to explore the new ternary compound is demonstrated in the Sr–Pt–Bi system. Because Pt–Bi is considered as a new critical charge-transfer pair for superconductivity, it inspired us to investigate the Sr–Pt–Bi system. With a thorough calculation of all the known stable/metastable compounds in the Sr–Pt–Bi system and crystal structure predictions, the thermodynamic stability of hypothetical stoichiometry, SrPtBi2, is determined. Following the high-temperature synthesis and crystallographic analysis, the first ternary bismuthide in Sr–Pt–Bi, SrPtBi2 was prepared, and the stoichiometry was confirmed experimentally. SrPtBi2 crystallizes in the space group Pnma (S.G. 62, Pearson Symbol oP48), which matches well with theoretical prediction using an adaptive genetic algorithm. Using first-principles calculations, we demonstrate that the orthorhombic structure has lower formation energies than other 112 structure types, such as tetragonal BaMn...

We report on the optimization of interface structure in ZnSnP2 solar cells. The effects of back electrode materials and related interface on photovoltaic performance were investigated. It was clarified that a conventional structure Mo/ZnSnP2 showed a Schottky-behavior, while an ohmic-behavior was observed in the Cu/ZnSnP2 structure annealed at 300 °C. STEM-EDX analysis suggested that Cu–Sn–P ternary compound was formed at the interface. This compound is considered to play an important role to obtain the ohmic contact between ZnSnP2 and Cu. In addition, it was clarified that the aqua regia etching of ZnSnP2 bulk crystals before chemical bath deposition process for the preparation of buffer layer was effective to remove the layer including lattice defects introduced by mechanical-polishing, which was supported by TEM observations and photoluminescence measurements. This means that the carrier transport across the interface was improved because of the reduced defect at the interface. Consequently, the conver...

Owing to their high extinction coefficient and moderate band gap, cadmium chalcogenides are known as common semiconductors for photoelectric conversion. Nevertheless, no ideal cadmium chalcogenide with proper band structure is available yet for photoelectrochemical hydrogen evolution. In this work, we modified the band structure of CdTe via alloying with Se to achieve a ternary compound (CdSe0.8Te0.2) with n-type conduction, a narrower band gap, and a more negative band position compared to those of CdSe and CdTe. This novel material exhibits strong light absorption over a wider spectrum range and generates more vigorous electrons for hydrogen reduction. As a result, a photoelectrode based on nanoflake arrays of the new material could achieve a photocurrent density 2 times that of its CdSe counterpart, outperforming similar materials previously reported in the literature. Moreover, the quick transfer of holes achieved in the novel material was found to depress photocorrosion processes, which led to improv...

The ternary compound CuV2S4 exhibits an excellent performance as anode material for sodium ion batteries with a high reversible capacity of 580 mAh g–1 at 0.7 A g–1 after 300 cycles. A Coulombic efficiency of ≈99% is achieved after the third cycle. Increase of the C-rate leads to a drop of the capacity, but a full recovery is observed after switching back to the initial C-rate. In the early stages of Na uptake first Cu+ is reduced and expelled from the electrode as nanocrystalline metallic Cu. An increase of the Na content leads to a full conversion of the material with nanocrystalline Cu particles and elemental V embedded in a Na2S matrix. The formation of Na2S is evidenced by 23Na MAS NMR spectra and X-ray powder diffraction. During the charge process the nanocrystalline Cu particles are retained, but no crystalline materials are formed. At later stages of cycling the reaction mechanism changes which is accompanied by the formation of copper(I) sulfide. The presence of nanocrystalline metallic Cu and/or...

The ternary compound, CuBi2O4, a 1:1 stoichiometric derivative of the two component oxides CuO and Bi2O3, has attracted attention from the solar water splitting and photocatalysis communities as a p-type semiconductor responsive to visible light. This study demonstrates that solution combustion synthesis (SCS) can be used to prepare powders not only of this compound but also nanocomposites with either CuO or Bi2O3 in excess. This was simply done by tuning the SCS precursor mixture composition. The synthesized crystalline samples were characterized by powder X-ray diffraction (with Rietveld refinement for phase purity), diffuse reflectance UV–visible spectroscopy, electron microscopy, and photoelectrochemical (PEC) techniques. The band structure and photoactivity of these oxides were probed by linear sweep voltammetry and by measuring their photoaction spectra (internal photon-to-electron conversion efficiency vs wavelength). The photoactivity (attributed to hydrogen evolution and CO2 photoreduction) was c...

A ternary compound semiconductor ZnSnP2 has the order–disorder transition, where the ordered and disordered phases are chalcopyrite (I42d, a = 5.651 A, c = 2a) and sphalerite (F43m, a = 5.651 A), respectively. In this study, the quantitative relationship between bandgap and long-range order parameter η was investigated by analyzing ZnSnP2 bulk crystals obtained by various cooling rates in crystal growth. The Chipman and Warren method was used to evaluate the long-range order parameters from X-ray difffaction profiles. The results showed that the long-range order parameter η decreases from 0.94 to 0.54 with the increase in cooling rates, and the bandgap gradually reduced from 1.60 to 1.37 eV, corresponding to the η value. It was also demonstrated that bandgap tuning of ZnSnP2 was possible by controlling the long-range order parameter through annealing process. This study clarified the effects of the order–disorder phenomena on bandgap in a model material, ZnSnP2, based on the evaluation of long-range ord...

Semiconductor nanowires are versatile building blocks for optoelectronic devices, in part because nanowires offer an increased freedom in material design due to relaxed constraints on lattice matching during the epitaxial growth. This enables the growth of ternary alloy nanowires in which the bandgap is tunable over a large energy range, desirable for optoelectronic devices. However, little is known about the effects of doping in the ternary nanowire materials, a prerequisite for applications. Here we present a study of p-doping of InxGa1-xP nanowires and show that the growth dynamics are strongly affected when diethylzinc is used as a dopant precursor. Specifically, using in situ optical reflectometry and high-resolution transmission electron microscopy we show that the doping results in a smaller nanowire diameter, a more predominant zincblende crystal structure, a more Ga-rich composition, and an increased axial growth rate. We attribute these effects to changes in seed particle wetting angle and increased TMGa pyrolysis efficiency upon introducing diethylzinc. Lastly, we demonstrate degenerate p-doping levels in InxGa1-xP nanowires by the realization of an Esaki tunnel diode. Our findings provide insights into the growth dynamics of ternary alloy nanowires during doping, thus potentially enabling the realization of such nanowires with high compositional homogeneity and controlled doping for high-performance optoelectronics devices.

K2Hg2Te3 was synthesized via a mercury-flux synthesis pathway. Single-crystal and powder X-ray diffraction reveal the compound to be isostructural to its lighter congener K2Hg2Se3, yet exhibiting enhanced photoconductivity and electrical conductivity of (several) orders of magnitude and a decreased thermal conductivity and band gap. In this report, we elaborate on the synthesis and properties of the novel ternary compound.

Buffer layers, such as CdS and MgxZn1–xO (MZO), are critical for CdTe and other thin film polycrystalline solar cells. A ternary compound, such as MZO, allows for interface engineering by adjusting...

We report here on the discovery of the superconductivity of a new ternary compound LaRh2Ga2, which possesses a CaBe2Ge2-type structure. Electrical resistivity and magnetic susceptibility measurements reveal that LaRh2Ga2 undergoes a superconducting transition at 3.7 K and exhibits type-II superconductivity. The T-linear behavior of the upper critical field is likely induced by the two-gap superconducting state because of its structural features (i.e., its noncentrosymmetric structure). A transition at Tc of specific heat suggested that the LaRh2Ga2 is a weak electron-phonon-mediated superconductor. Comparison with a related superconductor demonstrates that there is an important factor other than electron-phonon coupling strength that induces higher Tc in the LaTM2Ga2 system with a noncentrosymmetric CaBe2Ge2-type structure.

The ammoniated magnesium chloride hexammoniate compound (HEX) is the key precursor phase required for the production of anhydrous magnesium chloride by the Australian Magnesium (AM) process. It is produced by direct ammoniation of MgCl2-saturated ethylene glycol solutions at 323 K. To determine the conditions required to form HEX, the C2H4[OH]2-rich part of the MgCl2–NH3–C2H4[OH]2 system was investigated at 323 ± 0.5 K. Seven phase regions were determined. These were: NH3(g)+LiqT, HEX+LiqT+NH3(g), HEX+LiqT, HEX+T+LiqT, T+LiqT, MgCl2·3EG+T+LiqT, and LiqT. The symbol T represents a ternary compound of composition MgCl2·2NH3·2C2H4[OH]2, and LiqT represents a ternary liquid phase. To produce only hexammoniate in the AM process, bulk ammonia levels need to be maintained at levels of greater than about (11 to 13) % (w/w) NH3. At lower ammonia levels, the formation of T-phase is promoted, resulting in coprecipitation of HEX and T-phase.

Using ab initio calculations, we have probed the effect of all 4d transition metals as potential alloying elements for RuO 2 (space group P4 2 /mnm, prototype rutile) on the phase stability and Seebeck coefficient. Nb additions were identified to increase both the phase stability and the Seebeck coefficient. Based on this design proposal, the ternary compound was synthesized by combinatorial reactive sputtering. X-ray diffraction data suggest that Nb is incorporated in the rutile structure with the solubility limit in the range 3—4 atom %. Nanorod formation is observed at Nb contents ≥2.9 atom %. Rutile coordination is present in all specimen, while with increasing Nb content Nb 2 O 5 coordination appears. This may be understood based on our ab initio molecular dynamics simulations. Surface coarsening on the atomic scale occurs due to O cross-linking of two neighboring NbO 6 octahedra. Hence, it is reasonable to assume that NbO 6 octahedra contribute toward the experimentally observed formation of nanorods.

The ammoniated magnesium chloride compounds MgCl2·nNH3, where n is 2, 4, or 6, are potentially usable as materials for producing anhydrous magnesium chloride. The MgCl2−NH3−CH3OH system was investigated at 298 K to determine phase stability regions for hexammoniate (HEX), tetrammoniate (TET), and diammoniate (DI). Five phase regions were determined. These were: HEX+Liq, HEX+T+TLiq, T+TLiq, MgCl2·6CH3OH+T+TLiq, and a ternary liquid phase, TLiq. The phase represented by the symbol T is a previously unknown ternary compound of composition MgCl2·4NH3·2CH3OH, and Liq refers to the liquid phase with a composition along, or very close to, the NH3−CH3OH binary. An additional five phase regions were also predicted based on the existence of known crystalline phases. These were: HEX+Liq(17.45 %NH3/MeOH)+NH3, HEX+TET+T, TET+DI+T, DI+T+MgCl2, and MgCl2·6CH3OH+T+MgCl2. The ternary phase was unstable, breaking down to produce ammonium chloride, ammonia, and magnesium methoxide (Mg(CH3O)2). These were all partially solub...

Equilibrium phase relation and solubility data for the rare earth trichloride TmCl3·6H2O and cadmium chloride in aqueous media were investigated. The corresponding equilibrium phase diagram in the ternary system TmCl3−CdCl2−H2O at 298.15 K was constructed. The results showed that the system was complicated and consisted of four stable equilibrium solid phases [CdCl2·2.5H2O, CdCl2·H2O, Cd3TmCl9·15H2O (3:1 type), TmCl3·6H2O]. The new compound Cd3TmCl9·15H2O was found to be congruently soluble in the system. The 3:1 type compound obtained was identified and characterized by the method of X-ray diffraction, X-ray diffraction single-crystal structure analysis, thermogravimetry, and differential thermogravimetry (TG, DTG). It belongs to a monoclinic system, with space group P2(1)/n, a = 1.2267(4) nm, b = 2.0034(7) nm, c = 1.2321(4) nm, β = 113.793(5)°, V = 2.7706(17) nm3, Dc = 2.554 g·cm−3, Z = 4. The standard molar enthalpy of solution of Cd3TmCl9·15H2O in deionized water was measured to be (29.73 ± 0.40) kJ·m...

We report solar cells based on highly confined nanocrystals of the ternary compound PbS(x)Se(1-x). Crystalline, monodisperse alloyed nanocrystals are obtained using a one-pot, hot injection reaction. Rutherford back scattering and energy-filtered transmission electron microscopy suggest that the S and Se anions are uniformly distributed in the alloy nanoparticles. Photovoltaic devices made using ternary nanoparticles are more efficient than either pure PbS or pure PbSe based nanocrystal devices.

Reported are the synthesis of the new ternary compound Ba3Cd2Sb4 and its structure determination by single-crystal X-ray diffraction. Ba3Cd2Sb4 crystallizes with the monoclinic space group C2/m (No. 12); unit cell parameters a = 17.835(2) A, b = 4.8675(5) A, c = 7.6837(7) A, and beta = 112.214(1) degrees; Z = 4. Its structure can be viewed as made of Ba2+ cations and [Cd2Sb4] double chains that are interconnected through Sb-Sb bonds to form 2D infinity2[Cd2Sb4]6- layers. The bonding arrangement in Ba3Cd2Sb4 can also be derived from other known structure types that feature similar fragments, such as TiNiSi, Ca3AlAs3, and Ca5Al2Sb6. Tight-binding linear muffin-tin-orbital band structure calculations are presented as well and show that the constituent elements have closed-shell configurations, indicative of Ba3Cd2Sb4 being a Zintl phase with poor metallic behavior. Crystal orbital Hamilton population analyses on selected atomic interactions in this structure are discussed within the context of the site preference, manifested in the mixed-cation compounds and Ba3-xAxCd2Sb4, where A = Ca, Sr, Eu, and Yb.

The thermodynamic properties of the congruently melting Cs3CeCl6 compound, which is known to exist in the CeCl3-CsCl system, were studied by differential scanning calorimetry and Knudsen effusion mass spectrometry. The heat capacity of solid and liquid Cs3CeCl6 was measured as a function of temperature in the range (300 to 1100) K. The thermodynamic activities of CsCl and CeCl3 were determined in the twophase field {Cs3CeCl6(s) + liquid}. These data were used to calculate the whole set of thermodynamic functions for the solid and liquid compound as well as the temperature variation of the Gibbs free energy and enthalpy of compound formation according to the reaction CeCl3(s,l) + 3CsCl(s,l) ) Cs3CeCl6(s,l). Several compounds may exist in LnX3-MX mixtures (Ln ) lanthanide, X ) halide, M ) alkali metal). These systems have relatively simple phase diagrams when they include the lighter alkali metal halides (LiX and NaX), while those with KX, RbX, and CsX exhibit generally several compounds of stoichiometry, M3LnX6 ,M 2LnX5, and MLn2X7. The stability of these compounds depends on the nature of both cations (lanthanide Ln, alkali M) and anions X. 1-3 We have paid much attention to the M3LnX6 stoichiometric compounds that exist in most LnX3-MX systems 4-11 and have a more extended stability range than those of other stoichiometry. These congruently melting compounds were found 12 to exist also in the CeCl3-MCl systems (M ) K, Rb, and Cs). The present work reports on the thermodynamic properties of the Cs3CeCl6 compound. It has been established earlier that this compound is metastable at ambient temperature. 12,13 It undergoes a solid-solid state transition at 676 K and melts congruently at 1078 K with the respective enthalpies (7.8 ( 0.4 and 67.4 ( 0.8) kJ · mol -1 . 2,3,14 Its formation enthalpy from the system componentssCsCl and CeCl3swas determined as -26.0 kJ · mol -1 at 298.15 K 12 by solution calorimetry.

The enthalpies of phase transitions and heat capacity were measured by differential scanning calorimetry for CeBr3 as well as the Rb3CeBr6 and Cs3CeBr6 congruently melting compounds. A polynomial heat capacity dependence with respect to temperature was used to fit the experimental data. By combining these results with the entropy at 298.15 K, temperatures, and enthalpies of phase transitions, the thermodynamic functions of CeBr3, Rb3CeBr6, and Cs3CeBr6 were calculated up to T = 1100 K.

The electronic structure of the ternary intercalated graphite beta-KS(0.25)C3 is studied by means of a first-principles density functional theory approach. The nature of the partially filled bands is analyzed, and the K sublayers of the intercalate are shown to have an important contribution to the Fermi surface. This K-based contribution confers a sizable three-dimensional character to the conductivity even if considerably less than that for the related binary KC8. The electronic structure of beta-KS(0.25)C3 differs noticeably from that of the related ternary compound, KH(x)C4. The charge transfer is analyzed, and a way to evaluate it, which can be used in general for intercalated graphites, is proposed. The charge transfer per C atom in this ternary material is shown to be smaller than that in the KC8 binary compound despite a more favorable stoichiometry ratio between K and C.

Understanding how solids form is a challenging task, and few strategies allow for the elucidation of reaction pathways that are useful for designing new solids. Here, we describe an unusual multistep reaction pathway that leads to the formation of AuCuSn(2), a new ternary intermetallic compound that was discovered as nanocrystals using a low-temperature solution route. The formation of AuCuSn(2) using a modified polyol process occurs through a multistep pathway that was elucidated by taking aliquots throughout the course of the reaction and studying the products using a variety of techniques. The reaction proceeds through four distinct steps: (a) formation of Au nanoparticles at or near room temperature, mediated by a galvanic reaction between Au(3+) and Sn(2+) (forming Au(0) and Sn(4+), precipitated as SnO(2) that forms a shell around the nanoparticles), (b) formation of NiAs-type AuSn nanoparticles, along with Cu and Sn, upon addition of NaBH(4), (c) aggregation and thermal interdiffusion to form AuCu(x)Sn(y) alloy nanoparticles, and (d) nucleation of intermetallic AuCuSn(2), which has an ordered NiAs-derived structure. The proposed mechanism was tested by starting the reaction with the AuSn intermediate. AuSn nanoparticles were synthesized separately and reacted with Cu and Sn nanoparticles, and ordered AuCuSn(2) formed as expected. Elucidation of this reaction pathway has important implications for guiding the design of new intermetallic solids, as well as for controlling the synthesis of complex multimetal nanocrystals.

The phase relationships of the In2O3−TiO2−CaO and In2O3−TiO2−SrO systems have been studied at 1350 °C in air. The In2O3−TiO2−CaO system contains a ternary compound Ti6In6CaO22 crystallizing in an incommensurate structure. The In2O3−TiO2−SrO system, on the other hand, is a simple ternary phase diagram without any ternary phases. The structure of Ti6In6CaO22 can be expressed by an incommensurate composite model that consists of two subsystems: the first subsystem, containing the InO6 octahedral layer and the Ti atoms in the TiOx layer, is rather rigid and can be reasonably represented with the averaged structure within the main lattice, a = 5.951(1) A, b1 = 3.422(1) A, c = 6.352(1) A, and β = 108.32(1)°; the second subsystem, consisting of only the O2 atoms in the TiOx layer, can be expressed with a smaller subcell, a = 5.951(1) A, b2 = 2.464(1) A, c = 6.352(1) A, and β = 108.32(1)°. The overall structure was refined in the superspace group C2/m(0β0)s0, β = q/b* = 0.389(1) by using the program, JANA2000. T...

Following the discovery of spinel structured silicon and germanium nitrides, we investigated the possibility of intermediate compositions or even solid solution in that new system. The multianvil syntheses were performed at 23 GPa and above 2000 °C. The synthesis products from a wide range of mixtures of low-pressure phases of Si3N4 and Ge3N4 gave rise to ternary silicon germanium nitride with the spinel structure. The results showed a complete solid solution between the two end members at the experimental conditions. The structure refinement also showed a strong site preference of silicon and germanium. The silicon atoms preferentially fill the octahedral sites and the germanium atoms preferentially fill the tetrahedral sites. Both γ-Si3N4 and γ-Ge3N4 were predicted to be wide band gap semiconductors. Therefore, the complete solid solution between those two end members could give rise to a new family of tunable wide band gap semiconductors.

We demonstrate the realization of the high-brightness and high-efficiency light emitting diodes (LEDs) using dislocation-free indium gallium nitride (InGaN)/gallium nitride (GaN) multiquantum-well (MQW) nanorod (NR) arrays by metal organic-hydride vapor phase epitaxy (MO−HVPE). MQW NR arrays (NRAs) on sapphire substrate are buried in spin-on glass (SOG) to isolating individual NRs and to bring p-type NRs in contact with p-type electrodes. The MQW NRA LEDs have similar electrical characteristics to conventional broad area (BA) LEDs. However, due to the lack of dislocations and the large surface areas provided by the sidewalls of NRs, both internal and extraction efficiencies are significantly enhanced. At 20 mA dc current, the MQW NRA LEDs emit about 4.3 times more light than the conventional BA LEDs, even though overall active volume of the MQW NRA LEDs is much smaller than conventional LEDs. Moreover, the fabrication processes involved in producing MQW NRA LEDs are almost the same for conventional BA LED...

Nanosized Ce1-xCuxOy materials were prepared by complexation−combustion method. The structural characteristics and redox behaviors were investigated using X-ray diffraction (XRD), temperature progr...

Sodium manganese oxide with a 2 × 4 tunnel structure (Na-2 × 4) was hydrothermally synthesized from Na−birnessite material in NaOH solutions at relatively low temperatures. The Na+ extraction and alkali-metal ion insertion reactions were investigated by chemical and X-ray analyses, SEM observation, FT-IR spectroscopy, TG-DTA analyses, pH titration, and Kd measurements. A considerable amount (81%) of Na+ ions in the 2 × 4 tunnel sites were topotatically extracted by acid treatment, accompanied by a slight change of the lattice parameters. Alkali-metal ions could be inserted into the 2 × 4 tunnel sites of the acid-treated sample (Na-2 × 4 (H)), mainly by an ion-exchange mechanism. The pH titration study showed that Na-2 × 4 (H) had simple monobasic acid behavior toward alkali-metal ions with a relatively low exchange capacity below pH 10; the exchange capacity increased in the order Cs+ < Li+ < Na+ < K+ ≅ Rb+ at pH 6. The distribution coefficient (Kd) study on Na-2 × 4 (H) showed the selectivity sequence of...

Lithium intercalation compounds based on lithium manganese oxides are of great importance as positive electrodes for rechargeable lithium batteries. It is widely accepted that Li+ may be extracted (deintercalated) from such lithium manganese oxides accompanied by oxidation of Mn up to a maximum oxidation state of +4. However, it has been suggested recently that further Li+ removal may be possible. Among the mechanisms that have been proposed to charge balance the removal of Li+ are Mn oxidation beyond +4 or loss of O2-. To investigate this phenomenon we have selected Li2MnO3, a layered compound Li[Li1/3Mn2/3]O2 with a ready supply of mobile Li+ ions but with all Mn already in the +4 oxidation state. We show that a substantial quantity of Li (at least 1.39 Li) may be removed. At 55 °C this occurs exclusively by oxidation of the nonaqueous electrolyte, thus generating H+ which exchange one-for-one with Li+ to form Li2-xHxMnO3. The presence of H+ between the oxide layers results in a change of the layer stac...

This paper focuses on the preparation and characterization of a titanium−tin mixed oxide (Ti,Sn)O2 with anatase structure. The preparation method is based on a sol−gel technique using titanium tetr...

6Li and 2H MAS NMR in conjunction with X-ray diffraction is used to study the acid leaching of the layered Mn(IV) compound Li2MnO3 (i.e., Li[Li0.33Mn0.67]O2). Lithium NMR shows that the lithium ions are progressively removed from the lithium layers during leaching, the reduction in lithium content in the layers correlating directly with the concentration of a new local environment for lithium that contains both manganese ions and protons in the first cation coordination sphere. The composition of these samples may be written as H1-xLix[Li0.33Mn0.67]O2, indicating that H+/Li+ ion exchange has occurred. 2H MAS NMR shows unequivocally that deuterons are present in these structures, following leaching in D2SO4/D2O. X-ray diffraction confirms that leaching is associated with the shearing of the oxygen layers to form a structure with an AABBCC stacking sequence of the oxygen layers. This stacking sequence is also found in isostructural compound HCrO2. The hydrogen bonding between the oxygen layers is proposed t...

Investigation of the reaction of La2CuO4 with several binary metal oxides in the solid state at elevated temperatures has revealed three different reaction pathways. Reaction of La2CuO4 with strong...

A novel and simple chemical reduction route at room temperature is described to synthesize nanocrystalline CdS, ZnS, and CdxZn1-xS. In the method, anhydrous CdCl2, or ZnCl2, S, and KBH4 powders react at room temperature in various organic solvents, and the effect of the solvent on the quality of the nanoparticle product is investigated. Among the solvents used, tetrahydrofuran is shown to produce the highest quality single-phase nanoparticles. The nanoparticles are characterized by X-ray diffraction, transmission electron microscopy, UV−vis absorption, and photoluminescence. The particle size ranges from 4 to 8 nm. In the CdxZn1-xS, the lattice structure gradually changes from cubic to hexagonal with increasing percentage of Zn in the ternary compound CdxZn1-xS. The nanoparticles exhibit broad emission peaks that shift to shorter wavelength with increasing percentage of Zn in the ternary compound CdxZn1-xS. The control of the composition of CdxZn1-xS nanoparticles may lead to the development of ideal mate...

This paper presents a new method of synthesis, mechanochemical activation, for the preparation of the Sr3Ti2O7 Ruddlesden−Popper (RP) phase. The results obtained from different starting reagents (SrO, SrCO3, or Sr(OH)2·8H2O and TiO2 anatase) and mechanical activation systems (vibrating and planetary mills) are compared. An optimized protocol is established that permits one to avoid the high temperatures and long reaction times needed in the classical solid-state reaction method; as a byproduct, very pure phases with controlled particle sizes are isolated as well. The products were studied by X-ray diffraction at room temperature and above, thermal analysis techniques, infrared spectroscopy, and scanning electron microscopy. The insight obtained in this work can be extrapolated to other Sr2[Srn-1TinO3n+1] Ruddlesden−Popper materials that have not been isolated, until now, as single phases.

Isolated, gigantic tin clusters of 56 atoms are discovered in the ternary compound Ba(16)Na(204)Sn(310) (cubic, F(-)43m, Z = 1, a = 25.2041(8) A) made by direct fusion of the elements at 800 degrees C. The cluster, made of four face-fused pentagonal dodecahedra, has 36 pentagonal faces and 90 edges, and resembles a concave fullerene "dented" at four places. It is made of three- and four-bonded tin atoms and is "stuffed" with four barium cations, [Ba(4)@Sn(56)](36-). This is the largest main group naked cluster in the solid state besides the fullerenes. Also occurring in the structure are two other isolated clusters of tin, Sn(16-n) (n = 0, 1, 2, 3, or 4) and Sn(8).

Nanocomposite materials of CoIICoIII2-xAlxO4−Al2O3 (0 ≤ x < 1.63) have been prepared from biphasic xerogels that contain the cobalt hydrotalcite-like compound CoII0.73CoIII0.27(OH)2.00(NO3)0.23(CO3...

An “unreacted shrinking core” model was used to describe the behavior of a fixed-bed reactor during the reaction between gas-phase H2S and perovskite-type sorbents (i.e., La2CuO4, LaMnO3, and LaCoO3). Optimization of a single adjustable parameter (i.e., the effective diffusivity of H2S through the sulfided perovskite layer) results in an excellent agreement between experimental H2S breakthrough curves and model predictions for different sorbents, temperatures, and H2S inlet concentrations. The values of effective diffusivity thus obtained are on the order of 2−10 cm2/h. For La2CuO4, for which data were available at different temperatures, the effective diffusivity was also found to follow an Arrhenius-type expression with an activation energy of approximately 3 kcal/mol.

A general route for the synthesis of homogeneous mixed-element oxides, based on the use of block polyalkylene oxide copolymers and single-source molecular precursors, is described. Thermolytic deco...

This paper offers direct evidence for the electrochemical intercalation of oxygen in an oxide with the K2NiF4 structure, namely, La2CuO4, at room temperature. Organic solvents, as well as water, allow that reaction to occur. The charge-to-mass ratio evaluated from a comparison with fluoride intercalation implies that either OH- or Oδ- species are being intercalated. Comparison with previous work seems to favor the latter. If an oxygen with lower charge is moving, that could indeed explain why oxygen conductivity can be observed at such low temperatures.

An electrochemical impedance spectroscopy (EIS) study of three members of the family of compounds LixNi1-yCoyO2 (y = 0, 0.2, and 1) has been performed by taking spectra at closely spaced bias potentials over the potential windows of utilization as cathodes in lithium-ion batteries. The spectra have been interpreted in terms of electronic and ionic transport properties. It has been found that, for x values greater than about 0.9, all the compounds show semiconductive properties with a specific resistance that increases with decreasing Ni content. For x close to about 0.9−0.8, the properties change into those of a metal-like material in which the ionic conductivity becomes the limiting factor. The transition between these two limiting conditions clearly appears in the impedance spectra.

PbTiO3 has been successfully synthesized at reduced temperatures (500−700 °C) using neither organics (including alkoxides) nor undesirable halides. Water-soluble peroxytitanic complexes [Ti(OH)3O2]...

M ferrites (M = Ni and Cu) were prepared for the CO2 decomposition reaction. The mechanisms of reduction and oxidation of M ferrites were investigated by thermogravimetric analysis and X-ray diffra...

Reactions between calcium and strontium substituted cobaltite ceramic membranes and calcium silicate sealing materials