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Co-free Li-rich layered oxides are gaining interest as feasible positive electrode materials in lithium-ion batteries (LIBs) in terms of energy density, cost reduction, and alleviating safety concerns. Unfortunately, their commercialization is hindered by severe structural degradation that occurs during electrochemical operation. The study at hand demonstrates advanced structural engineering of a Li-rich Co-free oxide with composition Li1.1Ni0.35Mn0.55O2by spray pyrolysis and subsequent calcination of an aqueous precursor, creating a segregated structure of two distinct layered phases with space groups R3̅m(rhombohedral) and C2/m(monoclinic). This particular structure was investigated with powder neutron diffraction, high-resolution analytical transmission electron microscopy imaging, and electron energy loss spectroscopic characterization. This complex structure contributes to the high electrochemical stability and good rate capability observed for this compound (160 mAh/g at C/3 and 100 mAh/g at 1C).These results provide new insights into the feasibility of developing and commercializing cobalt-free positive electrode materials for LIBs.

Ruddlesden-Popper Nd0.8Sr1.2Ni0.8M0.2O4-d (M = Ni, Co, Fe) nickelates have been characterized as prospective oxygen electrode materials for solid electrolyte cells. XRD studies showed that these oxides retain tetragonal K2NiF4-type structure in air until at least 900degC. Average thermal expansion coefficients of Nd0.8Sr1.2Ni0.8M0.2O4-d calculated from the structural data are in the range 14.5-15.8 ppm/K. TGA studies revealed that these nickelates are oxygen-deficient in air at temperature above 700degC but tends to oxygen stoichiometry or minor excess on cooling. Incorporation of cobalt or iron into nickel sublattice of Nd0.8Sr1.2NiO4-d reduces oxygen deficiency and electrical conductivity. Electrochemical impedance spectroscopy studies of symmetrical cells showed that porous Nd0.8Sr1.2Ni0.8M0.2O4-d electrodes applied onto Ce0.9Gd0.1O2-d electrolyte exhibit quite similar performance, with lowest values of polarization resistance (0.8 O[?]cm2 at 800degC) observed for M = Ni. The polarization resistance can be further decreased (down to 0.04 O[?]cm2 at 800degC for M = Ni) by surface modification with PrOx.

The β–α (order–disorder) transition in the silanides ASiH3(A = K, Rb) was investigated by multiple techniques, including neutron powder diffraction (NPD, on the corresponding deuterides), Raman spectroscopy, heat capacity (Cp), solid-state 2H NMR spectroscopy, and quasi-elastic neutron scattering (QENS). The crystal structure of α-ASiH3corresponds to a NaCl-type arrangement of alkali metal ions and randomly oriented, pyramidal, SiH3–moieties. At temperatures below 200 K ASiH3exist as hydrogen-ordered (β) forms. Upon heating the transition occurs at 279(3) and 300(3) K for RbSiH3and KSiH3, respectively. The transition is accompanied by a large molar volume increase of about 14%. The Cp(T) behavior is characteristic of a rotator phase transition by increasing anomalously above 120 K and displaying a discontinuous drop at the transition temperature. Pronounced anharmonicity above 200 K, mirroring the breakdown of constraints on SiH3–rotation, is also seen in the evolution of atomic displacement parameters and the broadening and eventual disappearance of libration modes in the Raman spectra. In α-ASiH3, the SiH3–anions undergo rotational diffusion with average relaxation times of 0.2–0.3 ps between successive H jumps. The first-order reconstructive phase transition is characterized by a large hysteresis (20–40 K). 2H NMR revealed that the α-form can coexist, presumably as 2–4 nm (sub-Bragg) sized domains, with the β-phase below the phase transition temperatures established from Cpmeasurements. The reorientational mobility of H atoms in undercooled α-phase is reduced, with relaxation times on the order of picoseconds. The occurrence of rotator phases α-ASiH3near room temperature and the presence of dynamical disorder even in the low-temperature β-phases imply that SiH3–ions are only weakly coordinated in an environment of A+cations. The orientational flexibility of SiH3–can be attributed to the simultaneous presence of a lone pair and (weakly) hydridic hydrogen ligands, leading to an ambidentate coordination behavior toward metal cations.

Copper hexacyanoferrate, CuII[FeIII(CN)6]2/3·nH2O, was synthesized, and varied amounts of K+ions were inserted via reduction by K2S2O3(aq). Ideally, the reaction can be written as CuII[FeIII(CN)6]2/3·nH2O + 2x/3K++ 2x/3e–↔ K2x/3CuII[FeIIxFeIII1–x(CN)6]2/3·nH2O. Infrared, Raman, and Mössbauer spectroscopy studies show that FeIIIis continuously reduced to FeIIwith increasing x, accompanied by a decrease of the a-axis of the cubic Fm3̅munit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction, ∼20% of the FeIII, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of ∼26 wt % upon heating to 180 °C, above which the structure starts to decompose. The crystal structures of CuII[FeIII(CN)6]2/3·nH2O and K2/3Cu[Fe(CN)6]2/3·nH2O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)6groups are vacant, and the octahedron around CuIIis completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the −Cu–N–C–Fe– framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ions.

Here we demonstrate that the anomalous magnetic properties of iron oxide nanoparticles are correlated with defects in their interior. We studied the evolution of microstructure and magnetic properties of biphasic core|shell Fe1–xO|Fe3−δO4nanoparticles synthesized by thermal decomposition during their topotaxial oxidation to single-phase nanoparticles. Geometric phase analysis of high-resolution electron microscopy images reveals a large interfacial strain at the core|shell interface and the development of antiphase boundaries. Dark-field transmission electron microscopy and powder X-ray diffraction concur that, as the oxidation proceeds, the interfacial strain is released as the Fe1–xO core is removed but that the antiphase boundaries remain. The antiphase boundaries result in anomalous magnetic behavior, that is, a reduced saturation magnetization and exchange bias effects in single-phase nanoparticles. Our results indicate that internal defects play an important role in dictating the magnetic properties of iron oxide nanoparticles.

By combining molecular dynamics (MD) simulations with 29Si and 27Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy, we present a comprehensive structural report on rare-earth (RE) aluminosilicate (AS) glasses of the RE2O3–Al2O3–SiO2(RE = Y, Lu) systems, where the latter is studied for the first time. The structural variations stemming from changes in the glass composition within each RE systemas well as the effects of the increased cation field-strength (CFS) of Lu3+relative to Y3+are explored and correlated to measured physical properties, such as density, molar volume, glass transition temperature, and Vickers hardness (HV). 29Si NMR reveals a pronounced network ordering for an increase in either the RE or Al content of the glass. Al mainly assumes tetrahedral coordination, but significant AlO5and AlO6populations are present in all structures, with elevated amounts in the Lu-bearing glasses compared to their Y analogues. The MD-derived oxygen speciation comprises up to 3% of free O2–ions, as well as non-negligible amounts (4–19%) of O[3]coordinations (“oxygen triclusters”). While the SiO4groups mainly accommodate the nonbridging oxygen ions, a significant fraction thereof is located at the AlO4tetrahedra, in contrast to the scenario of analogous alkali- and alkaline-earth metal-based AS glasses. The average coordination numbers (CNs) of Al and RE progressively increase for decreasing Si content of the glass, with the average CN of the RE3+ions depending linearly on both the amount of Si and the fraction of AlO5groups in the structure. The Vickers hardness correlates strongly with the average CN of Al, in turn dictated by the CFS and content of the RE3+ions. This is to our knowledge the first structural rationalization of the well-known compositional dependence of HVin RE bearing AS glasses.

An array of magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy experiments is applied to explore the surface reactions of a mesoporous bioactive glass (MBG) of composition Ca0.10Si0.85P0.04O1.90when subjected to a simulated body fluid (SBF) for variable intervals. Powder X-ray diffraction and 31P NMR techniques are employed to quantitatively monitor the formation of an initially amorphous calcium phosphate surface layer and its subsequent crystallization into hydroxycarbonate apatite (HCA). Prior to the onset of HCA formation, 1H → 29Si cross-polarization (CP) NMR evidence dissolution of calcium ions; a slightly increased connectivity of the speciation of silicate ions is observed at the MBG surface over 1 week of SBF exposure. The incorporation of carbonate and sodium ions into the bioactive orthophosphate surface layer is explored by 1H → 13C CPMAS and 23Na NMR, respectively. We discuss similarities and distinctions in composition−bioactivity relationships established for traditional melt-prepared bioglasses compared to MBGs. The high bioactivity of phosphorus-bearing MBGs is rationalized to stem from an acceleration of their surface reactions due to presence of amorphous calcium orthophosphate clusters of the MBG pore wall.

Binderless hierarchically porous monoliths have been produced from silicalite-1 and ZSM-5 zeolite powders by a rapid and facile powder processing method where the zeolite powders are assembled in a graphite die and subjected simultaneously to a compressive pressure and a pulsed current. Pulsed current processing (PCP) or, as it is commonly called, spark plasma sintering, enables rapid thermal processing of zeolite powder assemblies with heating and cooling rates at 100 °C/minute or more, which results in the formation of strong powder bodies without any addition of secondary binders. Nitrogen adsorption measurements show that it is possible to form strong zeolite monoliths by PCP that maintain between 85 and 95% of the surface area of the as-received silicalite-1 and ZSM-5 powders. Line-broadening analysis of X-ray powder diffraction data by the Rietveld method and high-resolution electron microscopy showed that the formation of strong interparticle bonds is associated with a local amorphization reaction at the interfacial contact points between the zeolite particles. The PCP-treated binderless ZSM-5 monoliths display a high selectivity in xylene isomer separation.

A nitrogen‐rich aluminosilicate with nominal composition La17Si9Al4N33has been synthesised at 1500–1650 °C under a N2atmosphere by reaction of La metal, AlN and Si3N4. Its crystal structure was solved and refined in space group F$\bar {4}$3m, with a= 15.4279(6) Å and Z= 4, to Rf= 1.9 %. The structure contains two novel types of discrete tetrahedral aluminosilicate clusters, with respective nominal compositions Al4Si4N17and Si5N16, with La atoms in between. Bulk samples were also investigated by powder X‐ray and electron diffraction. The 29Si and 27Al solid‐state NMR results indicate that the phase contains minor amounts of oxygen and has a narrow compositional range with probable end limits La17Si9Al4N33and La16.67Si9Al4N32O.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The structures of one synthetic and two natural chlorites of the chlinochlore type were explored using X-ray diffraction, magic-angle spinning nuclear magnetic resonance (NMR) and Mössbauer spectroscopy. Rietveld refinements indicated that all structures are of the trioctahedral ordered IIbpolytype. Mössbauer spectra provided the ratio IIFe/IIIFe but gave no evidence for the presence of IIIFe in the brucite-like sheet. We also report unit-cell parameters, Mössbauer isomeric shifts, Si NMR chemical shifts as well as 27Al isotropic shifts and quadrupolar coupling parameters. Very broad 29Si NMR peaks from the natural samples prevented us from obtaining accurate information on the Si-Al ordering in the tetrahedral sheets; the limitations of 29Si NMR as applied to natural chlorites are discussed. High-resolution 3QMAS NMR resolved the 27Al signal of the M4 octahedral site in the brucite-like sheet from the other three Al signals of crystallographically inequivalent octahedral positions.

Mg–Si–C–N ceramics were synthesized by reactive pyrolysis of poly(ureamethylvinyl)silazane (PUMVS) polymeric precursor filled with Mg metal powder. Pyrolysis of crosslinked polymeric composites with Mg loadings between 10 and 50 wt.% was carried out in argon atmosphere at temperatures up to 1600 °C. The metal–precursor reactions, ceramization and phase evolution were studied using thermogravimetry, infrared spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. Predominantly X-ray amorphous Mg–Si–C–N materials, containing up to 15 mol% Mg, were obtained at 1000 °C, with a homogeneous distribution of magnesium at a length scale above 100 nm. The incorporation of Mg in the materials proceeds in two steps: (i) conversion of the Mg metal to magnesium compounds and (ii) solid state diffusion, assisted by vapour phase transport, of Mg into the amorphous Si–C–N–H bulk. Mg retention in the materials at temperatures above 900 °C is realized due to the formation of Si–Mg–N bonds. Primary crystallization of SiC is initiated by magnesium induced partitioning of nitrogen in the Mg–Si–C–N materials. Stability of the amorphous Mg–Si–C–N phase and crystallization of MgSiN2at higher pyrolysis temperatures is governed by the free carbon content in the materials and the nitrogen partial pressure in the thermolysis atmosphere. The results indicate the feasibility of synthesizing monolithic MgSiN2-based ceramics through precursor pyrolysis.

Single crystals of the sialon Ce N-phase Ce₃Si_8 − xAl_xN_11 − xO_4 + x  (x ≈ 1.75) were obtained via a novel route, i.e. by first preparing a fully compacted body with phase constitutions far away from thermal dynamic equilibrium by means of a fast densification technique, spark plasma sintering, and then heat treating this compact in a sialon powder bed at 1600 °C in N₂ atmosphere for 24 h. The structure of the Ce N-phase was solved using MoKα single-crystal data and direct methods. It was refined in space group I2/a with a = 15.798(1), b = 4.8939(3), c = 17.990(1) Å, β = 114.816(4)°, V = 1262.4 Å3, to a weighted R(F_obs2) = 6.7% for 977 unique reflections. The isostructural La phase structure was refined with anisotropic thermal parameters for La and N/O atoms using time-of flight neutron powder diffraction data. The structure exhibits three structural kinds of N/O anions: 4/15 of these are N atoms which are triangularly coordinated by 3 Si/Al atoms, 2/15 are tetrahedron free apex O atoms which are in addition bonded to 3 Ce/La atoms while the remaining 9/15 are on sites that are statistically occupied by N and O atoms and which are bonded to 2 tetrahedral Si/Al atoms and 1–2 Ce/La atoms. Comparisons are made with a previous structural proposal deduced from solid state nuclear magnetic resonance spectra.

The Mn³⁺-containing oxide MnTaO₄ was synthesized at 1050 °C and 2 kbar partial oxygen gas pressure. It has a rutile-type structure, space group P4₂/mnm, with a = 4.7189(3), c = 2.9843(3) Å, and a statistical distribution of Mn/Ta. The structure was refined by the Rietveld method using both X-ray and neutron powder diffraction. The refinements, and energy-dispersive X-ray microanalysis, indicate that the phase may contain a small amount of Mn⁴⁺ and have the actual composition Mn_1.08(2)Ta_0.92(2)O₄. The magnetic susceptibility shows a maximum at 16 K and Curie–Weiss behavior at higher temperatures, with μ_eff = 5.11(4) μ_B per Mn atom. The susceptibility is consistent with spin-glass behavior: (i) the temperature at the susceptibility maximum is frequency-dependent and (ii) field cooled and zero-field cooled susceptibility curves differ below the maximum. Neutron powder diffraction data collected at 10 K does not show any sharp magnetic reflections, but a very broad reflection, with a full width at half maximum height of 7°, at a position corresponding to the 100 reflection is seen.

Large single crystals of the oxygen ion conductor BaBi3O5.5have been obtained, and its structure was investigated by single-crystal X-ray diffraction (XRD) and neutron diffraction (ND), electron diffraction, and high-resolution electron microscopy (HREM). The basic three-dimensional structure was refined, using single crystal ND data, in space group Im3mto a weighted Rvalue of 5.3% for 17 unique reflections, with Ba and Bi atoms statistically distributed on the 2(a) sites (0, 0, 0) and the O atoms on the 6(b) sites (12, 0, 0) with a refined occupancy of 36(1)%. The refined thermal-displacement parameters for the O atoms are highly anisotropic, with U11=U22=0.27(1) and U33=0.082(7) Å2. In addition, the structure is incommensurately modulated with the systematic absence conditions F〈hklmnp〉=0 unless h+k+l=2jand m+n+p=2j, implying the six-dimensional superspace group P:Im3m:Im3m, with a=4.3798(2) Å and modulation vectors q1=[α, 0, 0]*, q2=[0, α, 0]*, and q3=[0, 0, α]*with α=0.3835(1). The diffraction data and the HREM images indicate that the modulation is predominantly occuptional. The satellite reflections have comparable intensities in powder XRD and ND patterns, indicating furthermore that the modulation originates from ordering of both O atoms/vacancies and metal atoms.

A structural investigation of the incommensurately ordered compound Mn0.55Ta0.45O1.7has been carried out, using single‐crystal X‐ray diffraction data. The basic structure is related to the fluorite type with a monoclinic distortion. Electron diffraction (ED) patterns for various crystal orientations were used for determination of unit cell, incommensurate modulation vector and superspace group. The unit cell parameters and the length and direction of the incommensurate vector were refined using X‐ray powder diffraction (XRPD) data. P2/mwas chosen as the three‐dimensional space group for a subcell with parameters a= 3.5005(2) Å (√2/2 · af), b= 3.5730(2) (√2/2 · af), c= 5.0015(2) Å (af) and β = 91.677(7)°. From the systematic absences hklm: k+ m≠ 2n, the four‐dimensional superspace group was determined to be B: P2/m(α 0 c) with determined modulation vector components α = –0.1833(1) and γ = 0.3582(2). A total of 511 unique reflections (79 basic fluorite type, 268 first‐order and 164 second‐order satellites) were used in the structure refinement, which resulted in weighted R‐values of 5.6% for the fluorite type sublattice reflections, 5.5% for the first‐order satellites and 7.4% for the second‐order satellites. The Mn and Ta atoms were found to be both positionally and occupationally modulated and the oxygen atoms to be highly disordered. The structure is the first fluorite‐related modulated structure of an oxide that has been determined from single‐crystal data. The structural relation to the previously characterised disordered cubic phase Mn0.6Ta0.4O1.65and the diffuse scattering exhibited by it are discussed in the article.

The Mn2+-containing oxide Mn3Ta2O8 crystallises in the space group I41/a with a=11.2728(2) and c=9.8030(3) Å, and with a structure related to the cubic fluorite type. The compound is antiferromagnetic with a Néel temperature of 23 K. The magnetic structure at 10 K was determined from constant-wavelength (λ=1.47 Å) neutron powder diffraction (NPD) data and refined by the Rietveld method to RF=2.1% and S=1.3 for 80 reflections with magnetic contributions at 2θ≤60°. The magnetic moments, of magnitude 4.01(2) µB, lie in the ab plane and are antiparallel with the (001) planes. The spin ordering is similar to that in the cubic fluorite structure of UO2 but with 40% of the magnetic atoms replaced with non-magnetic Ta atoms. The non-magnetic crystal structure at 295 K was refined to RF=0.6% using time-of-flight (TOF) NPD data, anisotropic thermal parameters and 1943 reflections with d≥0.55 Å.

A nitrogen-rich sialon phase containing Sr or Eu, named the S-phase, has been reported to form in the M′-Si-Al-O-N systems with M′=Sr and Eu. A sample with overall composition Sr2Al2.5Si10O4N14.5 hot-pressed at 1800 °C for 2 h contained approximately 85 vol% of the S-phase, and in addition the α- and β-sialon phases and an amorphous phase. Its structure was solved from X-ray synchrotron powder data (λ=1.1608 Å), using direct methods, and was refined by the Rietveld method from 131 reflections in the 2θ range 10-59° to RF=2.7%, with the assumed composition Sr2Al2Si10O4N14, space group Imm2, a=8.2788(9), b=9.5757(9), c=4.9158(4) Å, V =389.7 Å3. The structure model was confirmed by its electron diffraction pattern and by high-resolution electron microscopy studies. The structure exhibits a tetrahedral network with high connectivity, each tetrahedron sharing corners with seven surrounding tetrahedra, and the Sr atoms, irregularly coordinated by eight O/N atoms, are found in tunnels extending along [001].

The crystallization process of Na1.6Zn0.8Si1.2O4 glass was studied by means of differential scanning calorimetry, X-ray powder diffraction and the platinum/carbon replication technique. Partially crystallized samples were made by rapidly cooling samples from elevated temperatures using the DSC apparatus, and the ionic conductivity of the materials was determined by means of impedance measurements conducted at lower temperatures where the crystallization rate was negligible. The glass was found to crystallize at 830 K by precipitation and three-dimensional grain-growth of a crystobalite-type phase with the same composition as the glass. The overall activation energy for the crystallization process was determined from isothermal DSC measurements to be 340 kJ mol-1. The bulk ionic conductivity for partially crystallized samples increases smoothly from 9.3 x 10-5(O cm)-1 at 600 K for the glass to 2.4 x 10-3(O cm)-1 for the crystallized material.

The compositional region Na2ZnGeO4- Na2ZnGe2O6has been investigated by means of X-ray powder diffraction and conductivity measurements. Three different phases have been observed, all structurally related to the high-temperature modification of cristobalite. The powder pattern of the low-temperature modification of Na2ZnGeO4could be indexed on the basis of an orthorhombic cell. A high-temperature phase was observed at compositions close to Na1.85Zn0.925Ge1.075O4, which is apparently structurally related to the low-temperature form of Na2ZnGeO4and to KGaO2. The third phase, restricted to the composition Na2ZnGe2O6, could be assigned an orthorhombic cell similar to that of zinc chkalovite, Na2ZnSi2O6. The variation of the ionic conductivity with x in NaxZnx2Ge2−x2O4(1.25≤x≤2.00) has been studied and found to be similar to that observed in a previous study of the Na2ZnSiO4- Na2ZnSi2O6system. Na1.85Zn0.925Ge1.075O4is the best conductor, with σ≈1.10−3(Ω cm)−1at 600 K and Ea=0.54 eV. The structural and conductivity data for the zinc germanates are compared with previous findings in the Na2ZnSiO4- Na2ZnSi2O6system.

The systems Na2.2Zn0.9(MoO4)2-Na2.2Cd0.9(MoO4)2and Na2.2Zn0.9(MoO4)2-Na2.5Sc0.5(MoO4) 2have been investigated by means of X-ray powder diffraction, thermal analysis and impedance measurements. Complete solid solubility between the end compositions was observed in both systems. The ionic conductivity increases by one order of magnitude when all the Zn atoms are replaced by Sc or Cd. The Cd compound is the best conductor, with σ=1.6·10−5(Ω cm)−1at 575 K. The activation energy, which decreases from 0.85 eV for Na2.2Zn0.9(MoO4)2to 0.72 eV and 0.66 eV for the Sc and Cd analogues, respectively, was found to be correlated with the unit cell volume.

The Mn2+-containing oxide Mn3Ta2O8 has been synthesised at 1200°C in Ar atmosphere, and its structure has been solved from X-ray synchrotron powder data (λ0.65 Å) by direct methods. The structure was refined by the Rietveld method to RF=6.3%, with space group I41/a, a=11.2728(2), c=9.8030(3) Å, V=1243.47 Å3, from 1190 reflections with d≥0.65 Å. It is related to the fluorite structure with a≊√5af and c≊2af. The Ta atoms are octahedrally coordinated by oxygen atoms and the three crystallographically different Mn atoms by 7, 4 + 4 and 4 oxygen atoms. Electron diffraction patterns show the presence of weak superstructure reflections corresponding to a primitive unit cell with a′=a and c′=6c. The melting point of Mn3Ta2O8 is 1470°C in Ar atmosphere. It is a semiconductor with an activation energy of 1.2 eV and a conductivity σ=3.7×10–5 S cm–1 at 600°C. The magnetic susceptibility shows a maximum at 23 K and a Curie-Weiss behaviour at higher temperatures, with µeff=5.7(1) µB per Mn atom. When Mn3Ta2O8 is oxidised at 1100°C in air an Mn-Ta oxide forms, which has a wolframite type structure with unit cell a=4.7574(5), b=5.7296(6), c=5.1133(4) Å and β=91.202(9)°.

Transition-metal oxide nanostructured materials are potentially attractive alternatives as anodes for Li ion batteries and as photocatalysts. Combining the structural and thermal stability of titanium oxides with the relatively high oxidation potential and charge capacity of molybdenum(VI) oxides was the motivation for a search for approaches to mixed oxides of these two metals. Challenges in traditional synthetic methods for such materials made development of a soft chemistry single-source precursor pathway our priority. A series of bimetallic Ti-Mo alkoxides were produced by reactions of homometallic species in a 1:1 ratio. Thermal solution reduction with subsequent reoxidation by dry air offered in minor yields Ti2Mo2O4(OMe)6(OiPr)6(1) by the interaction of Ti(OiPr)4with MoO(OMe)4and Ti6Mo6O22(OiPr)16(iPrOH)2(2) by the reaction of Ti(OiPr)4with MoO(OiPr)4. An attempt to improve the yield of 2by microhydrolysis, using the addition of stoichiometric amounts of water, resulted in the formation with high yield of a different complex, Mo7Ti7+xO31+x(OiPr)8+2x(3). Controlled thermal decomposition of 1–3in air resulted in their transformation into the phase TiMoO5(4) with an orthorhombic structure in space group Pnma, as determined by a Rietveld refinement. The electrochemical characteristics of 4and its chemical transformation on Li insertion were investigated, showing its potential as a promising anode material for Li ion batteries for the first time. A lower charge capacity and lower stability were observed for its application as an anode for a Na ion battery.

Ruddlesden-Popper Nd0.8Sr1.2Ni0.8M0.2O4-δ(M = Ni, Co, Fe) nickelates have been characterized as prospective oxygen electrode materials for solid electrolyte cells. XRD studies showed that these oxides retain tetragonal K2NiF4-type structure in air until at least 900°C. Average thermal expansion coefficients of Nd0.8Sr1.2Ni0.8M0.2O4-δcalculated from the structural data are in the range 14.5-15.8 ppm/K. TGA studies revealed that these nickelates are oxygen-deficient in air at temperature above 700°C but tends to oxygen stoichiometry or minor excess on cooling. Incorporation of cobalt or iron into nickel sublattice of Nd0.8Sr1.2NiO4-δreduces oxygen deficiency and electrical conductivity. Electrochemical impedance spectroscopy studies of symmetrical cells showed that porous Nd0.8Sr1.2Ni0.8M0.2O4-δelectrodes applied onto Ce0.9Gd0.1O2-δelectrolyte exhibit quite similar performance, with lowest values of polarization resistance (0.8 Ω⸱cm2at 800°C) observed for M = Ni. The polarization resistance can be further decreased (down to 0.04 Ω⋅cm2at 800°C for M = Ni) by surface modification with PrOx.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.