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In this study, the ternary phase diagram of the Tc–Al–B system is constructed by a combination of an evolutionary algorithm and density functional theory calculations. Four novel phases are predicted, including three binary compounds (P Al7B15, Cmcm TcAl2, and C2 TcAl3) and one ternary compound (Cmmm Tc2AlB2). All predicted structures are mechanically, dynamically, and thermodynamically stable. Among the predicted phases, P Al7B15 resembles the experimental structure of Al0.93B2 and Cmmm Tc2AlB2 corresponds to the 212-type MAB phase. Due to the in- and out-of-plane anisotropic chemical bonding in Cmmm Tc2AlB2, a tetragonal two-dimensional (2D) Tc2B2 structure could be possibly exfoliated by chemical removal of Al atoms. The electronic structure calculations indicate that the 2D Tc2B2 structure and its potential layered precursors are all metallic. Furthermore, the chemical reactivity of H, F, O and, OH ligands with the 2D Tc2B2 surface is studied and the associated 2D surface-functionalized Tc2B2 derivatives are found to be metallic. It is revealed that the F and O functional groups strengthen the surface atomic layer of 2D Tc2B2 and enhance the Young's moduli.

Ternary compound CuSbSe2-alloyed PbTe, CumPb100SbmTe100Se2m (CLAST), presents outstanding n-type thermoelectric transport behavior and features hierarchical Cu-based precipitates and interstitials that can balance phonon and carrier transport. Results show that a small amount of CuSbSe2 (∼3%) alloying in CLAST can realize a room-temperature carrier concentration of ∼1.7 × 1018 cm−3 and then optimize the power factor, and simultaneously precipitate out embedded Cu-based nanostructures in the matrix to lower the lattice thermal conductivity. Additionally, extra Cu atoms adding in CLAST can form interstitials and further improve both the carrier concentration to ∼3.0 × 1018 cm−3 and carrier mobility to ∼1227.8 cm2 V−1 s−1 at room temperature, which benefits a maximum power factor of ∼20.0 μW cm−1 K−2 in Cu3.3Pb100Sb3Te100Se6. Moreover, the Cu interstitials together with massive Cu-based nanoprecipitates can strongly scatter a wide set of phonons, and largely lower the lattice thermal conductivity to ∼0.44 W m−1 K−1 in Cu3.4Pb100Sb3Te100Se6 at 623 K. Finally, these Cu-based hierarchical structures in CLAST samples can synergistically optimize the phonon and carrier transport properties and contribute to a high ZT of ∼0.5 at 300 K and a peak ZT of ∼1.4 at 723 K. A remarkably high ZTave of ∼0.94 at 300–723 K is achieved in Cu3.3Pb100Sb3Te100Se6 due to high ZT values in the low temperature range, outperforming other high-performance n-type PbTe-based thermoelectric materials.

Both electronic and ionic conductivities are of high importance to the performance of anode materials for Li-ion batteries. Many large capacity anode materials (such as Ge) do not have sufficiently high electronic and ionic conductivities required for high-rate cycling. Here, we report a novel ternary compound, copper germanium phosphide (CuGe2P3), as a high-rate anode. Being synthesized via a facile and scalable mechanochemistry method, CuGe2P3 has a cation-disordered sphalerite structure and offers higher ionic and electronic conductivities and better tolerance to volume change during cycling than Ge, as confirmed by first principles calculations and experimental characterization, including high-resolution synchrotron X-ray diffraction, HRTEM, SAED, XPS and Raman spectroscopy. Furthermore, the results suggest that CuGe2P3 has a reversible Li-storage mechanism of conversion reaction. When composited with graphite by virtue of a two-stage ball-milling process, the yolk–shell structure of the amorphous carbon-coated CuGe2P3 nanocomposite (CuGe2P3/C@Graphene) delivers a high initial coulombic efficiency (91%), a superior cycling stability (1312 mA h g−1 capacity after 600 cycles at 0.2 A g−1 and 876 mA h g−1 capacity after 1600 cycles at 2 A g−1), and an excellent rate capability (386 mA h g−1 capacity at 30 A g−1), surpassing most Ge-based anodes reported to date. Moreover, a series of cation-disordered new phases in the Cu(Zn)–Ge–P family with various cation ratios offer similar Li-storage properties, achieving high reversible capacities with high initial coulombic efficiencies and desirable redox chemistry with improved safety.

Motivated by the recent experimental discovery of high-temperature carbonaceous sulfur hydride (C–S–H), we have systematically explored the superconductivity of a carbonaceous lanthanum hydride (C–La–H) ternary compound in the pressure range of 50–250 GPa. Based on first-principles calculations and strong-coupling Migdal–Eliashberg theory, we find that a hitherto unreported LaC2H8 ternary system is dynamically and thermally stable above 70 GPa in a clathrate structure with space group Fmm and exhibits a superconducting critical temperature, Tc, in the range of 69–140 K.

The new ternary compound Y4Be33Pt16 was prepared from elements by arc melting, and its crystal structure was determined from single-crystal X-ray diffraction data (space group I4[combining macron]3d, a = 13.4849(3) A). The material is the first representative of a new structure type of complex intermetallic compounds and reveals a cage-like crystal structure. Analysis of chemical bonding by means of the electron localizabilty approach indicates ionic interaction of yttrium with the rest of the crystal structure, characteristic for cage compounds, in particular for clathrates. In contrast to the mostly two-centre bonding in the framework of clathrates, the new compound is characterized by a multi-centre interaction within the framework, caused by the demand of the valence electrons in the system. The non-centrosymmetric material enters the superconducting state at TC = 0.9 K.

The influence of Al on the thermoelectric properties of the half-Heusler (HH) TiNiSn compound is reported. The research combined ab initio Density Functional Theory (DFT) calculations with experimental microstructure evaluation and measurements of the transport properties up to 750 K. It is shown that Al addition to the Ti sub-lattice results in an increase of the absolute value of the Seebeck coefficient and electrical resistivity in polycrystalline TiNiSn, while preserving the n-type behavior of the ternary compound, in addition to a significant reduction of the thermal conductivity. In (Ti0.99Al0.01)NiSn, upon 1% Al substitution of Ti, an improvement of 17% in the thermoelectric figure of merit (0.42 at 723 K) compared to pure TiNiSn was observed. Theoretical lattice thermal conductivity calculations are applied to shed light on the different scattering mechanisms in this class of materials. It is shown that the major contribution to the lattice thermal conductivity reduction is stimulated by the presence of Sn-rich inclusions, in addition to an influence of mass fluctuation scattering due to substitution of Ti by Al. Although it is shown that in the widely applied polycrystalline TiNiSn, an addition of the acceptor Al dopant could not fully compensate n-type electronic active defects (e.g. grain boundaries) for obtaining p-type materials, the currently reported results pave a route for thermoelectric optimization of MNiSn (M = Ti, Ni, Sn) n-type half-Heusler compounds.

Cu1.45Ni1.45Te2 ternary compound was synthesized by solid-state ball-milling method and densified via spark plasma sintering (SPS) and cold-pressing with annealing (CPA) techniques. The effect of densification techniques on the thermoelectric properties was studied. SPS sample showed negative Seebeck coefficient values for the entire temperature range, while CPA sample changed the sign of the Seebeck coefficient above 573 K from n-type to p-type. The electrical conductivity was higher for SPS sample than for CPA sample for the entire temperature range. Hence, SPS sample exhibited 167% increased zT when compared to CPA sample. It is confirmed that the SPS technique is more suitable to obtain a high zT value than the CPA technique for n-type Cu1.45Ni1.45Te2 sample. Also, the effect of carrier concentration was studied and the change in the carrier concentration was done by Se-doping. From a series of thermoelectric measurements, it was found that the undoped sample exhibited a high zT of about 0.004 at 400 K and the Se-doped sample exhibited a zT of 0.001 at 750 K. It means that Se-doping mainly influences the shifting of the operating temperature of TE performance from room temperature range to mid-temperature range. The formation of n-type TE material was realized due to the delocalization of electron density on Te-ions, which compensate the Cu-vacancies resulting in the n-type conduction behaviour. Se-doping modifies the reaction of Te-ions with cations affecting the delocalization of electron density, which shifts the conduction type from n-type to p-type behaviour.

Pressure has become a useful parameter to prepare novel functional materials. Considering the excellent performance of ZnO and Zn3N2 and the formation of strong Zn–O, Zn–N, and N–O bonds in the known compounds, we explored potential Zn–N–O ternary compounds with interesting properties. With the aid of first-principles swarm-intelligence search calculations, we identified a hitherto unknown ZnN2O3 ternary compound with a symmetry of P21. Its remarkable feature is that N pairs interconnect the distorted Zn-centered decahedrons, in which the Zn atom forms bonds with one N and six O atoms. The compression of ZnO + NO2 + N2 might be an easy way to synthesize ZnN2O3. Electronic property calculations disclose that ZnN2O3 is a wide band gap semiconductor with a gap value of 3.48 eV, which is larger than those of ZnO and Zn3N2. Moreover, the high-pressure phase diagram of Zn–N binary compounds was explored with a wide range of chemical compositions. Two metallic N-rich zinc nitrides (e.g., ZnN2 and ZnN4) are proposed, containing intriguing N2 dimers and zigzag N chains. ZnN2 exhibits superconducting properties, and becomes the first example of superconductor in zinc nitrides. Our current results unravel the unusual stoichiometry of Zn–N–O compounds and provide further insight into the diverse electronic properties of zinc nitrides under high pressure.

Bi2X3 (X = S, Se, and Te) binary compounds have been widely studied as thermoelectric materials and reference topological insulators. Replacing one of the X atoms with a different atom Y of the same group has resulted in a new family of ternary compounds Bi2X2Y (X, Y = O, S, Se, and Te), which have attracted increasing attention very recently. By means of first-principles calculations within density functional theory, we have systematically studied the geometric structures and electronic properties of the whole family of these ternary compounds. We find that these compounds can be divided into two major groups. The first is traditional semiconductors, which include (i) Bi2O2Y, (ii) Bi2S2Y, and (iii) Bi2OY2. The other is topological insulators, which are (i) Bi2Se2Y and (ii) Bi2Te2Y. The optimized lattice parameters, band gaps as well as effective masses are in excellent agreement with recently available experimental measurements. In particular, we have found a new semiconductor material Bi2S2Te, which possesses an orthorhombic structure in space group pnma with a moderate direct gap of 0.5 eV at the HSE06 level and a small hole effective mass (∼0.22m0), which should favour fast hole transport and deserves further experimental studies. This work provides a road map for the exploration of the fundamental properties of the ternary compounds in this family as well as for their practical applications at the device level.

Phase equilibria in the Li–B–C ternary system have been investigated by X-ray powder diffraction, scanning electron microscopy, electron probe microanalysis and differential scanning calorimetry. The isothermal section of the phase diagram has been constructed over the whole concentration range at 400 °C. The Li–B–C system is characterized by the formation of six ternary compounds: τ1 – LiBC3, τ2 – LiB2C2, τ3 – LiBC, τ4 – Li2B2C, τ5 – LiB6C and τ6 – LiB13C2. The formation of the new ternary compound LiB2C2 (own structure type, space group P63/mmc, a = 2.5930(3) A, c = 22.680(1) A) and binary BC3 (space group Pm2, a = 2.4588(4) A, c = 6.770(2) A) has been revealed. The crystal structures are discussed in the light of the underlying graphene and heterographene networks.

Defect calculations are standard practice for understanding the electronic structure of dopants and alloying elements in semiconductors and insulators. However, these calculations have untapped potential to quantitatively determine thermodynamic properties of doped semiconductor systems. We present a methodology which couples defect energetics and compound formation energies to determine defect concentrations in a host material as functions of temperature and chemical equilibrium. From these defect concentrations we find the solvus boundaries of the host phase in a multi-dimensional composition space. As an example, we present first-principles calculations of the solvus boundaries of PbTe and PbS in Na–Pb–Te and Na–Pb–S. We calculate the formation energies of compounds in Na–Pb–S–Te and the defect energetics of a large number of intrinsic and Na-containing defects in PbTe and PbS. With these, we obtain equilibrium defect concentrations and solvus boundaries for PbTe and PbS. We find vacancies are the lowest-energy intrinsic defects in PbTe and PbS. We also find Na substituted for Pb is the lowest-energy Na defect in both PbTe and PbS. We find that the PbTe solvus boundary in Na–Pb–Te is a sharply peaked function of composition. We find negative defect formation energies for Na on Pb in PbS, suggesting the existence of a ternary compound in the Na–Pb–S system. The methodology presented herein is a general and straightforward way to extend the use of defect calculations from making inferences about the electronic structure of dopants to calculating solvus boundaries in multicomponent systems.

InGaAs nanowires offer great promise in fundamental studies of ternary compound semiconductors with variable composition and opens up a wide range of applications due to their bandgap tunability and high carrier mobility. Here, we report a study on the growth of Au-seeded InGaAs nanowires by metal-organic vapour phase epitaxy and present a model to explain the mechanisms that govern the growth and composition evolution in ternary III-V nanowires. The model allows us to further understand the limitations on the growth rate and incorporation of the two group III species imposed by the deposition conditions and some intrinsic properties of the material transport and nucleation. Within the model, the evolution of InGaAs nanowire growth rate and composition with particle size, temperature and V/III ratio is described and correlates very well with experimental findings. The understanding gained in this study should be useful for the controlled fabrication of tunable ternary nanowires for various applications.

We substitute indium present in the CuInS2 ternary compound by iron and zinc using a facile one-pot synthesis method. The quaternary compound of CuIn1−xMxS2 (M = Fe and Zn) was synthesized by dissolving CuCl, InCl3, FeCl3, Zn(ac)2 and SC(NH2)2 as precursors in 1-octadecene, oleylamine and oleic acid as non-coordinating, coordinating and capping agent solvents, respectively. Oleic acid, oleylamine and thiourea were used respectively as a hard Lewis base, borderline Lewis base (in comparison with oleic acid) and soft Lewis base to form appropriate complexes. The complex formation, structure, and optical properties of CuIn1−xMxS2 (M = Fe and Zn) nanoparticles were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible-near infrared (UV-vis-NIR) and photoluminescence (PL) spectroscopy. The absorption edge of solid solution samples can be tuned from 745 nm (visible) to 1200 nm (near infrared) by substitution of In3+ by Zn2+ and Fe3+, respectively.

The ternary compound Cu2SnS3 (CTS) was fabricated by a spray pyrolysis method. The influence of the Cu precursor concentration and substrate temperature on the properties of the prepared films was investigated in detail. X-ray diffraction spectroscopy & Raman spectroscopy, energy dispersive spectroscopy, UV-vis spectrophotometry, Four-probe Resistivity Testing and Stylus Profilometry were employed for the analysis of the structural, compositional, optical, electrical and morphological properties of the prepared CTS thin films. The characterization results showed that the CTS thin film fabricated under optimal conditions (substrate temperature 350 °C, Cu concentration 0.02 M) had an atomic ratio of Cu1.43SnS2.59, and presented as a tetragonal structure with preferential (1, 1, 2) orientation. Optical measurements showed that the thin film had a high absorption coefficient (>104 cm−1) with a band gap value of 1.16 eV. The resistivity of the sprayed CTS thin film was 11.6 × 10−2 Ω cm. All these properties indicated that the as-fabricated CTS thin film could be a promising absorber layer material for high efficiency thin film solar cells.

A systematic investigation is presented on the influence of Sn-substitution in the clathrate-I compound Ba(8)Zn(x)Ge(46-x-y)Sn(y), particularly for the crystal structure and thermoelectric properties including electrical resistivity, Seebeck coefficient, and thermal conductivity. Two series of samples were prepared to explore the changes for different Sn-contents, (y), and to define the optimum Zn-content, (x), for Ba(8)Zn(x)Ge(46-x-y)Sn(y). Sn-incorporation leads to a linear expansion of the unit cell parameters. Sn-atoms occupy the 6d and 24k positions of the clathrate type-I structure (SG Pm3n, standardized setting). Whereas the electrical resistivity and the Seebeck coefficient modify only slightly compared to Ba(8)Zn(x)Ge(46-x), the thermal conductivity is significantly decreased by the Sn-atoms incorporated into the clathrate-I framework. Furthermore the charge carrier mobility is larger and the effective mass (m* = 1.7 m(e)) is much smaller than those of the ternary compound Ba(8)Zn(x)Ge(46-x). The maximum thermoelectric figure of merit is improved by 80% and reaches ZT = 0.82 at 850 K for Ba(8)Zn(7.66)Ge(36.55)Sn(1.79).

Ternary inclusion crystals of cholic acid (CA) with two aromatic compounds, m-fluoroaniline (G1) and indene (G2), were investigated from a viewpoint of selective incorporation and release. Recrystallization of CA from an equimolar mixture of G1 and G2 gave the CA crystal in a 47 : 53 molar ratio of G1 to G2. This ternary crystal has a sandwich-type structure with a two-dimensional (2D) host cavity consisting of two non-equivalent sites, A and B. G1 tends to be included in the site A owing to hydrogen bonds, while G2 in the site B. This site affinity for each guest was confirmed in a bulk crystal as well as in a single crystal of the ternary compound. Thermogravimetric analysis revealed that the two guest molecules were released at two different temperature ranges of 50–100 °C and 100–120 °C. Heat treatment of the starting crystal at 90 °C for 10 min yielded the expected intermediate crystal, which had a bilayer structure with a one-dimensional (1D) cavity in a 60 : 40 molar ratio of G1 to G2. Moreover, irrespective of the guest ratios in the starting CA crystals, G1 was preferentially retained in the thermal guest-release process. Such preferential retention of G1 is attributable to the host–guest hydrogen bond between CA and G1 at the site A in the 2D cavity.

In the last few years nanostructure ZnO is being intensively investigated from the growth control, structural and physical characterization, to device performance. There are now increasing interests in a wide range of ZnO-based ternary compound nanostructures offering even larger possibilities. These compounds can be useful as multi-color light-emitting device, sensors, transparent electrodes, or catalysts. This Review summarizes typical ZnO-based ternary compound nanotubes and nanowires, which are fabricated based on either solid-state reactions with ZnO and/or porous templates, or on the vapour-liquid-solid process. Our focus is put on spinel-type compounds formed with oxides like Al2O3, Ga2O3, Fe2O3, Sb2O3, TiO2, and SnO2. The discussion includes the growth strategies, nanosize effects, and the associated reaction mechanisms. ZnMgO alloy nanowires, another technologically important ternary compound, are touched at the end, too.

A LaMnO3/CdS nanocomposite was prepared by a reverse micelle method and examined for its photocatalytic activity for H2 production from water containing electron donors (Na2S and Na2SO3) under visible light irradiation (λ > 420 nm). The prepared LaMnO3/CdS nanocomposite of 10–20 nm particle size showed 6 times higher photocatalytic activity than that of CdS; on the other hand, LaMnO3 showed no photocatalytic activity. It was also found that LaMnO3/CdS can continuously produce hydrogen from water in the presence of electron donors for more than 200 h. In order to account for the improvement in the activity, the valence edge potentials of CdS and LaMnO3 were investigated by photoemission yield measurements. The proposed energy band scheme for the LaMnO3/CdS composite suggests that photogenerated holes in the valence band of CdS can move to that of LaMnO3 and react with Na2S while photogenerated electrons remain in the conduction band of CdS and react with water to produce H2; this charge-carrier separation is responsible for the improved activity.

A single crystal of the cubic spinel LiMn2O4 was delithiated electrochemically at 4.06 V vs. Li/Li+ to probe the structural source of the inflection point at ca. 4.1 V vs. Li/Li+ in the discharge curve. The phase thus obtained was investigated by single-crystal X-ray diffraction and the structure refined. The structure is closely related to the original cubic structure, but the new space group is rhombohedral Rm and shows a one-dimensional modulation along the r direction with wave vector q ≈ 0.75c*. The cell parameters are: a = 5.762(1) A and c = 14.080(4), and the (3 + 1)-dimensional super space group is Rm(00γ). The modulated phase involves two unique Mn atoms with coordination polyhedra which differ significantly: one has an average Mn–O distance of 2.24(1) A, indicative of a lower oxidation state for the Mn ion; the other has an average Mn–O distance of 1.82(2) A, indicative of a higher oxidation state. Lithium ions appear to be extracted from the structure in a long-range-ordered two-dimensional arrangement between the cubic-close-packed oxygen layers; the manganese atoms are also arranged in charge-ordered Mn3+/Mn4+ sheets. These two features are the source of the modulation in the structure.

A new approach for the synthesis of a new type of ternary mesoporous La–Co–Zr mixed oxides with various atomic (La + Co/La + Co + Zr) ratios is reported. The synthesis method combines the advantages of the preparation of the clear soluble homogeneous metal oxides containing a cationic surfactant in acidic medium followed by the precipitation of this mixture in basic medium and hydrothermal treatment. These solids have high surface area, uniform mesopore size with a worm-hole like pore structure, good thermal stability and high component dispersion. They exhibit unusually high catalytic activity and resistance to SO2 poisoning in the complete methane oxidation as compared to bulk LaCoO3 perovskites.

Layered LixMnyO2 materials with the O3 (α-NaFeO2) structure have been synthesised by a low temperature ion exchange route from the corresponding sodium compounds. Previous studies have concentrated upon the undoped and singly doped families of O3 layered lithium manganese oxides. This is the first report of multiply doped analogues. The effects on electrochemical performance (ability to store reversibly large quantities of lithium and hence charge) and crystal chemistry of partially substituting some of the Mn ions with two dopants have been investigated. A range of structural (X-ray and neutron diffraction) and electrochemical (galvanostatic cycling and a.c. impedance) techniques as well as chemical analyses were utilised. The new materials, LixMny−2zMzM′zO2 (M, M′ = Li, Cu, Mg, Ni, Zn, Al and Co), offer high capacities in excess of 200 mA h g−1 at a rate of 50 mA g−1 (C/4) with the highest values being for the z = 0.025 series. The main advantage of the multiply doped materials over the previously reported undoped and singly doped O3 layered lithium manganese oxides is their far superior rate capability. All the compounds in this study irreversibly transform to spinel-like materials on extended cycling. This is not, however, detrimental to their electrochemical performance and is analogous to the behaviour of other lightly doped O3 layered lithium manganese oxides.

Density functional theory calculations of the calcium tungstate material scheelite CaWO4 have shown that water introduced into the bulk material remains undissociated and leads to swelling and layering of the structure, a behaviour which may resemble silicate clays more than three-dimensional poly-anionic materials, but which results in a structure that is even more similar to a rare hydrous calcium carbonate phase—a finding which suggests the existence of semi-crystalline hydrous precursor phases to the dehydrated scheelite material.

The oxidation behavior of Ti3AlC2 powders has been investigated in air by means of simultaneous TGA-DSC, XRD, Raman spectra, SEM, EDS and BET specific surface measurement to understand the intrinsic oxidation behavior of this newly developed ternary compound. The starting and complete oxidation temperatures determined by simultaneous TGA-DSC were 400 and 1120 °C, respectively. These temperatures are higher than those for TiC, suggesting that Ti3AlC2 is more oxidation resistant than TiC. An anomalous oxidation temperature range of 550–650 °C in which the final mass gains due to the isothermal oxidation of Ti3AlC2 powders at 550, 600 and 650 °C for 2 h are significantly greater than that at a higher temperature of 700 °C, was observed. This anomalous oxidation behavior suggests that direct reaction dominated with high oxidation kinetics in this temperature range, which was confirmed by SEM morphology observation and BET specific surface area measurement. The oxidation of Ti3AlC2 powders at temperatures below 700 °C resulted in two modifications of TiO2 (anatase and rutile). At temperatures above 800 °C the oxidation products consisted of rutile TiO2 and α-Al2O3.

Nanoscale layered tetratitanate K2Ti4O9 powders were prepared at relatively low temperature by a stearic acid method. The structures of the titanates and the products which had undergone H+, Ag+ exchange and intercalated by propylamine and NH2(CH2)3Si(OC2H5)3 (APS) were investigated by XRD, TEM, TG and BET analysis. Compared with the larger-size products prepared by a conventional solid state reaction, the nanoscale K2Ti4O9 takes in more intercalating molecules and leads to larger interlayer distances in the intercalated products, which may facilitate the exfoliation of the layered compound.

A polymerizable complex (PC) technique was utilized to prepare fine powders of high purity BaTinO2n + 1 with n = 1, 2 and 5 at lower temperatures than those used for the ordinary solid-state reaction procedure. The formation of pure BaTinO2n + 1 occurred when precursors obtained from PC-derived gel materials were heat-treated at 800–900 °C in static air for 2 h. BaTinO2n + 1 powders were subsequently converted to RuO2-loaded materials, and their photocatalytic activities for the decomposition of water were examined. While the RuO2–BaTi2O5 (n = 2) and RuO2–BaTi5O11 (n = 5) materials exhibited photocatalytic activity for water decomposition into H2 and O2 in approximately stoichiometric amounts (H2 ∶ O2 = 2 ∶ 1) under UV light irradiation with specific hydrogen gas evolution rates of 125 and 52 µmol h−1 g−1, respectively, the RuO2–BaTiO3(n = 1) exhibited a very low activity of less than 1 µmol h−1 g−1. The lack of a significant occurrence of photocatalysis in BaTiO3 was explained in terms of its crystal structure possessing only a very small polyhedral distortion.

Phosphate particles of the selected rare earth metals have been prepared, using an emulsion liquid membrane [ELM, water-in-oil-in-water (W/O/W) emulsion] system, consisting of Span 83 (sorbitan sesquioleate) as surfactant and EHPNA (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) as extractant (cation carrier). The rare earth ions are extracted from the external water phase of the ELM system and are stripped into the internal water phase, containing phosphoric acid solution, to form the corresponding rare earth phosphate particles. The morphology and size of the particles are well-controlled by using the ELM system, and submicrometer-sized spherical phosphate particles are obtained, while micron-sized and irregular-shaped phosphate particles are obtained in homogeneous aqueous solutions. The resulting submicrometer-sized spherical particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and thermal analysis (TG–DTA). The characterization of La-based particles revealed that the fine particles obtained were of hexagonal structure, but their crystalline structure was changed to a monoclinic structure by calcination at 1373 K. Composite LaPO4:Ce3+,Tb3+ phosphor particles were then prepared by transporting La3+, Ce3+, and Tb3+ ions simultaneously, with the resulting particles showing good photoluminescence at 545 nm. In the ELM system, the size of the particles is able to be controlled in the range of 0.28 to 0.65 μm by changing the concentration of Span 83, whereas that in the homogeneous system is about 0.7 μm.

Single-phase lithium manganese oxide spinels were synthesized in two steps: (1) the preparation of defective spinel precursors with different Li ∶ Mn ratios through lithium insertion into Li-birnessite manganese oxide in a LiNO3 flux at 400 °C, followed by (2) heat-treatment of the precursors at 750 °C in air. Depending upon the Li ∶ Mn ratio, the precursors yielded three types of single-phase spinels: a lithium-deficient type with lithium and oxygen deficiencies, stoichiometric LiMn2O4, and a lithium-rich type with lithium in the 16d-site of space group Fdm but with oxygen deficiency. The electrochemical measurements showed that good rechargeability on cycling between 3–4.3 V could be obtained in all the lithium-rich spinels Li[LixMn2 − x]O4 − δ, where 0 < x < 0.33 and δ < 0.2.

Monophasic BaTi4O9 powder has been prepared by an auto-ignition route. The auto-ignition of the gel, prepared by thermal dehydration of a pH adjusted citrate–nitrate solution, directly resulted in voluminous BaTi4O9 powder with traces of carbonaceous material. Calcination of the voluminous powder at 600°C produced pure nanocrystalline BaTi4O9 powder. Process parameters such as the amount of citric acid used for gelation and pH of the starting solution were found to have a signifant influence on the gel stability, temperature required for the phase formation and the powder characteristics. TEM micrographs revealed the nanocrystalline nature (crystallite size

Polycrystalline homogeneous lithium cobalt oxide powder was synthesized by a solid-state method using microwaves. The synthesis was carried out in a domestic microwave oven. LiCoO2 was synthesized with a microwave irradiation time of 20 min. This process remarkably reduced synthesis time and LiCoO2 was produced relatively quickly for the first time. The synthesized material showed reasonable electrochemical characteristics.

HNbWO6/(Pt,Cd0.8Zn0.2S) nanocomposites have been fabricated by successive intercalation reactions of HNbWO6 with [Pt(NH3)4]Cl2 aqueous solution, with n-C3H7NH2/n-heptane mixed solution, and the Cd(MeCO2)2–Zn(MeCO2)2 mixture in aqueous solution, followed by the reaction between Cd2+–Zn2+ and H2S in the interlayer of HNbWO6. The gallery height of HNbWO6/CdS*, HNbWO6/Cd0.8Zn0.2S*, HNbWO6/CdS, HNbWO6/Cd0.8Zn0.2S, HNbWO6/(Pt, CdS) and HNbWO6/(Pt,Cd0.8Zn0.2S) is less than 0.5 nm in each case. HNbWO6/(Pt,Cd0.8Zn0.2S) series nanocomposites show a broad reflectance over ca. 380–580 nm and are capable of efficient hydrogen evolution under the irradiation of visible light in the presence of Na2S as a sacrificial donor. The photocatalytic activities of HNbWO6/CdS and HNbWO6/Cd0.8Zn0.2S nanocomposites are superior to those of unsupported CdS and Cd0.8Zn0.2S and are enhanced by the the co-incorporation of Pt.

The electronic and structural properties of the layered ternary compound Ti3AlC2 have been determined using the ab initio pseudopotential method based on density functional theory. We have obtained the equilibrium lattice parameters, the equilibrium atomic positions in the unit cell, and interatomic distances. The calculated bulk modulus is 190 GPa and is comparable to that of TiC. The band structure, density of states (DOS) and effective charges are presented and compared with those of TiC. The band structure indicates that Ti3AlC2 is an electronic conductor. The electronic structure discloses that the bonding in Ti3AlC2 is anisotropic and metallic–covalent–ionic in nature. Compare to the structure of TiC, the presence of Al changes the Ti–C–Ti–C covalent bond chain into a Ti–C–Ti–C–Ti–Al bond chain through its reaction with Ti, forming the layered structure. Effective charge calculations suggest the ionic formula of Ti3AlC2 to be (Ti1.18+)(Ti0.59+)2(Al0.52−)(C0.92−)2.

A novel method based on the solid–liquid reaction in the Ti–Sn–C system was developed for the synthesis of Ti2SnC powders. In this process, Ti–Sn intermetallic compounds were formed in liquid Sn, then they further reacted with graphite powders to form Ti2SnC. The advantages of this solid–liquid reaction based method include low synthesis temperature, short reaction time and less impurity in the as-prepared powders. Investigations on the stability of Ti2SnC powders demonstrated that Ti2SnC was stable in Ar up to at least 1200°C. In air, however, a complex oxidation–decomposition–oxidation process was observed.

A mixed vanadium manganese oxide was synthesized through a chimie douce route. The synthesis proceeds via a cationic exchange reaction occurring between the layers of a synthetic rancieite, a lamellar manganic acid. The vanadium atoms were found to be at a distance from Mn close to the Mn–Zn distance in chalcophanite, a model for the phyllomanganates. XAS refinements did not reveal the presence of manganese atoms between the layers of either the protonic or Li-exchanged forms of the rancieite. Li insertion is largely impeded by the presence of dioxovanadium cations, which seem to be accommodated into one of the Li potential sites present in the Li-exchanged phase.

From different precursors, including γ-, β-MnO2, hollandite, and H+-form birnessite manganese oxides, well-crystallized Li1.33Mn1.67O4 spinels were synthesized at 400°C by using LiNO3 as a flux. Alkali metal ion adsorptivities of the spinels after delithiation were investigated. SEM observation showed that each spinel obtained preserved the morphology of its precursor. The lack of morphology change, and the time-dependence of the lithium insertion into the precursors, illustrate that the formation of the spinel is a topotactic template reaction. None of the delithiated spinels preserved the original ion-exchange sites in their precursors but all showed nearly the same high affinity for Li+, while the amount of uniform acidic sites increased and the steric hindrance during lithiation decreased in the order of spinels obtained from birnessite, hollandite, and γ-, β-MnO2. This is probably because birnessite has more (buffer) space for the accommodation of ions in its layered structure than other precursors with a tunnel structure and some part of the space remains after structural transformation to the spinel.

Competitive particle growth (CPG) theory and linear stability analysis are combined to study the potential patterning trends of two-salt Liesegang systems. The pattern formation is treated as a post-nucleation phenomenon. Experimental investigations show that some systems mainly give patterns where the bands of the two salts essentially alternate, while others (such as typically the PbI2–PbF2 system) yield patterns where the bands completely overlap. We report on observations in a variety of two-salt systems, where we find a spectrum of patterning trends which generally fall into either of two categories: “correlated” patterns (with band overlap) or “anti-correlated” (with band alternation). The systems considered are Co(OH)2–Mg(OH)2, Ni(OH)2–Mg(OH)2, PbI2–PbF2, Ag2Cr2O7–PbCr2O7, MnS–CuS and MnS–CdS. The analysis of the reaction–diffusion equations shows that the simple precipitation scheme would predominantly yield an alternation of bands of the two salts. To resolve this disagreement between theory and experiment in the PbI2–PbF2 case (and some other cases), another scenario involving the complex ions PbI+ and PbF+ was also considered. The analysis here yields a dominant overlap between the PbI2 and PbF2 bands conformly to the experimental result. This study on two-precipitate pattern formation gives clues on the possible reaction schemes actually involved in the precipitation process and suggests interesting experiments for eventual elucidations. The results and conclusions are revisited in the Discussion section.

An ultrafine (25-40 nm) powder of spinel lithium manganese oxide with composition Li 0.95 Mn 2 O 4 was obtained from decomposition of freeze drying nitrate precursors and heat treatment below 500 °C. Positive electrodes prepared with this material have been cycled between 4.6 and 3.1 V up to C/2 rate. The specific discharge capacity at such a rate decreases from 110 to 90 mA h g –1 after 80 cycles, with a low polarization only.

Photocurrent generation from Langmuir–Blodgett (LB) overlays on indium tin oxide (ITO) electrodes, where the active components are 2,4-bis[4-(dibutylamino)-2-hydroxyphenyl]squaraine (1) and the unsubstituted analogue, 2,4-bis[4-(dibutylamino)phenyl]squaraine (2), have been investigated. Dye 1 shows improved behaviour compared with the latter and differences in performance are attributed to a modified aggregate structure, this being indicated by variations in the LB film spectra. The photocurrent generation is enhanced by the presence of electron acceptors, e.g. N,N′-dimethyl-4,4′-bipyridinium diiodide (MV2+), but quenched by electron donors, e.g. hydroquinone (HQ). The concentration dependence is reported.

The mechanism of lithium intercalation in layered LiMnO 2 has been investigated by combining data from a variety of techniques, including powder X-ray and neutron diffraction, cyclic voltammetry and galvanostatic cycling. Whereas the diffraction data indicate the coexistence of layered and spinel phases at Li 0.5 MnO 2 after 5 charge(extraction)-discharge(insertion) cycles, the electrochemical data only change significantly on the first charge(extraction), near Li 0.5 MnO 2 . A rationale is provided by a model in which, on first extracting 0.5 Li from layered LiMnO 2 , displacement of Mn ions occurs into the lithium layers, forming regions with the local structure and composition of spinel. This can explain the presence of a 4 V peak in the cyclic voltammogram on the first charge. Long range order only develops on more extended cycling and since this does not alter significantly the Li + or e – energies, the electrochemistry does not change further. Load curves show significant hysteresis and this is linked to a domain-like microstructure with spinel imbedded in layered material. The marked difference between load curves for this material and LiMn 2 O 4 spinel indicates that the former does not convert to ‘normal’ spinel on cycling. By doping LiMnO 2 with as little as 10% Co the cooperative Jahn-Teller distortion due to localised high spin Mn 3+ (3d 4 ) disappears despite the high concentration of Mn 3+ and a substantial improvement in the ability to cycle lithium is obtained from 130 mAh g –1 to 200 mAh g –1 at 100 µA cm –2 .

Nano-sized Pd-particles anchored onto Ln 2 O 3 particles with Ln=La, Nd, Sm, Eu or Gd have been prepared by reduction of the Ln 4 PdO 7 precursor materials in a flowing gas mixture of CO and an inert gas (He or Ar). The reductions have been monitored by theromogravimetric (TG) and differential scanning calorimetric (DSC) measurements. The TG experiments show that the onset temperatures of the reduction varies from 450 to 575 °C with the lanthanoid used and Ln=Sm or Eu exhibit the lowest reduction temperatures. The air re-oxidation of the reduced materials back to their oxidised formed, e.g. Ln 4 PdO 7 , has also been studied by TG and this reaction starts at 280-340 °C depending on the lanthanoid used; the re-oxidation process occurs in two steps for all lanthanoids except Sm and Gd. The formation of Ln 4 PdO 7 is observed to be very fast. The prepared and reduced materials have been characterised by their X-ray powder diffraction (XRPD) patterns. The DSC studies and XRPD patterns of quenched samples suggest that the reduction process occurs in at least two steps. The reduced materials have also been characterised by transmission electron microscopy (TEM/EDS) studies and a wet-chemistry method for selective dissolution of Ln 2 O 3 has been used to extract the formed Pd nano-particles. Line-broadening analysis of the XRPD pattern of extracted particles suggests that the Pd particles are nanosized single crystals as the calculated particle size (20 nm) agrees fairly well with corresponding data from the TEM studies (5-20 nm). Reduced Ln 4 PdO 7 materials have been shown to exhibit three way catalytic activity for car exhaust clean-up (i.e. simultaneous oxidation of CO and hydrocarbons and reduction of NO) with T 50 values around 450 °C.

The structural transformation of vanadyl(V) phosphate dihydrate (V V OPO 4 ·2H 2 O, V/P = 1) and a Ga-containing vanadyl(V) phosphate dihydrate ([Ga(H 2 O)] x (V V O) 1–x PO 4 ·2H 2 O, V/P = 1 – x) in the presence of ammonia have been investigated. V V OPO 4 ·2H 2 O was transformed in the presence of an NH 3 –air–water vapour flow at temperatures of ca. 670 K mainly into distorted (NH 4 ) 2 (V IV O) 3 (P 2 O 7 ) 2 (V/P = 0.75). Additionally, the generation of crystalline V 2 O 5 (up to 10%) was observed, mainly representing the remainder of the vanadium of the precursor compound. [Ga(H 2 O)] x (V V O) 1–x PO 4 ·2H 2 O was synthesised by the replacement of a number of the (V V O) 3+ groups of the parent V V OPO 4 ·2H 2 O by [Ga(H 2 O)] 3+ . A similar solid-state transformation was observed when this material was treated under the same gas flow but, besides crystalline V 2 O 5 , a significant proportion of GaPO 4 was also formed. The heterogeneous catalytic ammoxidation of toluene to benzonitrile was applied as a test reaction in the temperature range 570–625 K for the evaluation of catalytic performance. The V V OPO 4 ·2H 2 O derived catalyst revealed an improved catalytic activity in comparison to similar catalysts obtained by the transformation of V(IV)-containing precursor compounds. It seems very likely that this is due to the existence of a proportion of crystalline V 2 O 5 . The catalytic activity of the Ga-containing material is much lower, but is still in the range of the V(IV)-derived catalysts. Characterisation of the parent samples and the generated products (after equilibration as well as catalytic runs) carried out by means of XRD, XPS and FTIR spectroscopy.

A metal-organic precursor method was adopted for the preparation of lithium-manganese spinel oxides. EPR spectra of Mn 2+ in solutions and in freeze-dried compositions, as well as IR and DSC of freeze-dried compositions, show that α-hydroxyorganic acids (such as lactic, malic and citric acids) chelate Mn 2+ via hydroxy and carboxylate groups. At 450°C, thermal decomposition of Li-Mn-organic acid precursors with Li/Mn=1.05/1.95 leads to the formation of non-stoichiometric Li[Li y Mn 2–y– Δ □ Δ ]O 4 spinels (0.03

The content of Mn in the semimagnetic semiconductors Cd 1– x Mn x Te and Sn 1– x Mn x Te bulk crystals and epitaxially grown layers was examined by X-ray spectrometry. The content of Mn in the investigated crystals and the homogeneity of samples were determined using electron probe microanalysis (EPMA). Bulk crystals and epitaxial layers were found to be homogeneous. In spite of this, the shapes of the Mn Lα valence band line from a bulk crystal and a layer with the same high content of Mn were found to be very different. In this case, the content of Mn estimated from EPMA also differed significantly from that estimated from magnetic measurements. The detailed analysis of Mn Lα lines and X-ray diffraction revealed the existence of a second MnTe phase in the epitaxial layer. The best match to the experimental Mn Lα line was given by spectral fitting with about 50% of Mn atoms bonded in a binary compound and 50% in a ternary compound. Therefore, in the case of epitaxially grown layers, where the different phases can be homogeneously distributed in the sample, the analysis of the valence lineshape can help to identify the existence of different compounds.

Reaction of oxalate anion with ZnAl layered double hydroxides (LDHs) gives rise to new LDH phases where either oxalate or aluminum oxalato complexes are intercalated depending on the exchange reaction conditions. Chemical characteristics, structural and spectroscopic data are presented.

High frequency EPR spectra of europium(II)-doped BaAl2O4 powder phosphor have been analysed. Spectral simulation was carried out by a Fourier transform Monte Carlo method using an equation derived from the second-order perturbation of the energy levels for S=7/2. It is found that the spectra can best be interpreted in terms of europium(II) ions in two different sites. One quarter of the europium(II) ions are located in a site with a ∣D∣ of 0.345 cm-1, and the remaining europium(II) ions are in a site with a ∣D∣ of 1.08 cm-1. Estimated values of ∣E∣ are equal to 1/3

The adsorption and reaction of methanol with SrTiO3(110) has been studied using temperature-programmed desorption and X-ray photoelectron spectroscopy. The main organic products are methane and ethane, though the exact ratio of these depends on sample history and defect levels in the surface and bulk. It is likely that the methanol dissociates to form adsorbed methyl groups associated with reduced Ti3+ and Ti2+ centres which were formed by Ar+ bombardment. We tentatively associate ethane formation with the latter sites and dialkyl formation, while methane production may be associated with the former sites and monoalkyl formation.

Porous GaCr mixed oxides were intercalated within the layers of α-zirconium phosphate using a colloidal suspension of phosphate previously swelled with vapours ofn-propylamine. The materials were characterised by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N2 adsorption–desorption. The surface acidity, both before and after poisoning with K, was evaluated by the following techniques: temperature programmed desorption of ammonia (NH3-TPD), IR spectroscopy measurements of adsorbed pyridine (Py-IR), isopropyl alcohol conversion tests and but-1-ene isomerisation tests. The catalytic activity in the vapour phase deep oxidation of methylene chloride was also tested. All samples were found to be moderately active as acid catalysts. The Bronsted type sites appeared to be located mainly on the phosphate layers and their concentration was found to be independent from the GaCr ratio. Lewis acid sites appeared to be located on the surface of the intercalated oxides and their concentration reaches a maximum for a GaCr ratio of 4060. This sample also shows the highest activity for the deep oxidation of methylene chloride.

A new ternary interstitial nitride Ni2W3N has been synthesized by the ammonolysis of different oxide precursors and characterized by powder X-ray diffraction and electron microscopy. This nitride crystallizes in the cubic space group P4132 (213) [Ni2W3N, a=6.663(1) A, Z=4] and is isostructural with Al2Mo3C. This compound belongs to the rare class of intermetallic ternary nitrides and carbides crystallizing with a filled β-Mn structure. Ni2W3N is not stable, it decomposes to a new compound NiW3N related to the distorted anti-perovskite, Ca3AsN structure.

Spinel LiMn 2 O 4 and LiMn 1.95 Ni 0.05 O 4 powders have been synthesized by a sol-gel method using an aqueous solution of metal acetates containing glycine. The dependence of the physicochemical properties of the spinel LiMn 2 O 4 powders on the calcination temperature and glycine quantity have been extensively investigated. The porous LiMn 2 O 4 and LiMn 1.95 N 0.05 O 4 electrodes were electrochemically characterized by using charge/discharge experiments along with ac impedance spectroscopy. The LiMn 1.95 Ni 0.05 O 4 electrode exhibited improved cycling performance in comparison with the stoichiometric LiMn 2 O 4 one in spite of a small reduction in the initial capacity. The good capacity retention of the LiMn 1.95 Ni 0.05 O 4 electrode is attributed to stabilization of the spinel structure by Ni doping for Mn ion sites and higher chemical diffusivity of lithium ions with cycling.

The effectiveness of a non-hydrolytic sol–gel process for the preparation of bicomponent oxides has been studied in the 1:1 system TiO 2 –ZrO 2 . Elemental analysis by energy dispersive X-ray analysis (EDXA) and by inductively coupled plasma (ICP) showed the same Ti:Zr ratio for the amorphous oxide and crystalline ZrTiO 4 which corresponds to that of the initial solution. The direct crystallization of ZrTiO 4 below 700 °C without the intermediate formation of TiO 2 or ZrO 2 indicates that the non-hydrolytic sol–gel process gives rise to the formation of homogeneous zirconium titanate gels.

A new type of hydrated rubidium molybdenum bronze has been synthesized, which was very unstable. It gave a orthorhombic structure with lattice constantsa=3.74(1), b=22.82(7), and c=3.85(1) A. Exchange of Na+ ion with Rb+ ion took place within 30 s. The exchange reaction, [Na+(H2O)n]x[MoO3x–]+Rb+ ⇆[Rb+(H2O)n]x[MoO3x–]+Na+ , took place in both directions by changing the Na+/Rb+ ratio in the mixed solution. A concentration of about 0.05 mol Na in the sample was the minimum value necessary to retain the structure of hydrated sodium molybdenum bronze. We obtained the blue rubidium bronze, Rb0.30MoO3 , by heating hydrated rubidium bronze in nitrogen. This is a new route to producing the metal bronze at low temperature. We also obtained rubidium decamolybdate by heating it in air. This is also a new method for producing rubidium decamolybdate by solid-state reaction.