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The desulfurization and dephosphorization performances have been considered to be the most challenging operations for refining ultra-clean steel. The distribution ratios of sulfur and phosphorus in the form of $$ L_{i} = {{\left( {\% \, i} \right)} \mathord{\left/ {\vphantom {{\left( {\% \, i} \right)} {\left[ {\% \, i} \right]}}} \right. \kern-0pt} {\left[ {\% \, i} \right]}} $$ as well as slag capacity concepts of sulfide and phosphate capacities in the form of $$ C_{{i^{m - } }} \propto (\% \, i^{m - } ) $$ have been extensively studied and widely applied for the description of desulfurization and dephosphorization abilities and potentials, respectively. However, the intrinsic limitations of two slag capacity concepts as sulfide and phosphate capacities regardless of slag oxygen potential $$ p_{{{\text{O}}_{2} }} $$ have seriously limited their direct applications into guiding the practical refining operations compared with the partitions or distribution ratios $$ L_{i} $$ . The theoretical limitations of sulfide and phosphate capacities have been extensively reviewed and critically assessed by comparison with the distribution ratios $$ L_{i} $$ in this contribution by taking two preferred thermodynamic conditions of both basic oxides concentration or slag basicity and slag oxygen potential as criteria. Meanwhile, the merits of two slag capacity concepts as measures for describing slag basicity like optical basicity have also been reviewed to be disruptive because the ratios of activity of free oxygen ion $$ a_{{{\text{O}}^{2 - } }} $$ in slags to activity coefficients $$ f_{{{\text{H}},i}} $$ of sulfide and monomer phosphate $$ {\text{PO}}_{4}^{3 - } $$ in slags as implicit parameters in the defined two slag capacity concepts cannot hold constants in most complex slags. Furthermore, the limitations of phosphate capacity in two ways have been restated. Moreover, the oxygen potential $$ p_{{{\text{O}_{2}} }} $$ shows a great effect on plots of the desulfurization and dephosphorization abilities against two slag capacity concepts of slags at a given temperature. The abnormally higher oxygen potential $$ p_{{{\text{O}_{2}} }} $$ can result in a suppression of the desulfurization ability of slags with a greater desulfurization potential, while the unreasonably smaller oxygen potential $$ p_{{{\text{O}_{2}} }} $$ can lead to a diminishing of the dephosphorization ability of slags with a larger dephosphorization potential. It has been verified by five case-studies covering desulfurization and dephosphorization operations that the partitions or distribution ratios $$ L_{i} $$ related to equilibrium quotients $$ k_{i} $$ of desulfurization and dephosphorization reactions of Fe-based melts by slags can be in good accordance with two preferred thermodynamic conditions. The reasonable application of two slag capacity concepts is recommended to estimate or determine the distribution ratios between slags and Fe-based melts with the aid of activity $$ a_{{\% ,{\text{O}}}} $$ of oxygen and activity coefficient $$ f_{\% ,i} $$ of sulfur and phosphorus in Fe-base melts.

For materials as BaCo0.4Fe0.4Zr0.1Y0.1O3-δ with three independent mobile charge carriers, hole, oxygen ion, and proton, a peculiar twofold diffusion and transition from hydration to hydrogenation in proton uptake are investigated by electrical conductivity relaxation method in this work. At 700 °C, the water incorporation reaction would happen in the formation of both hydration and hydrogenation. The hydration reaction would happen at the sacrifice of oxygen vacancy, and then, the incorporated proton diffuses from outer layer to the inner bulk. But due to much higher chemical diffusion coefficient of proton than oxygen vacancy, the highly mobile protons are charge compensated by holes, instead of waiting for the less mobile oxygen vacancy, and thus causes the speeding increased hole concentration, i.e., increased conductivity. So in the hydration reaction, the decoupled diffusion of proton and oxygen vacancy would result in a non-monotonic conductivity relaxation curve, i.e., twofold diffusion. After that, the proton uptake reaction would transit to hydrogenation, as total decreased conductivity in a monotonic curve.

The relativistic energies and Auger transition rates for the Rydberg series 1s23lnl′ 1,3F° (n = 3–6) of Be-like oxygen ions are determined by the saddle-point variation and saddle-point complex-rotation methods. Relativistic corrections and mass polarization effects are considered to improve the computational accuracy of the energy. The Auger branching ratios of the 1s22s and 1s22p decay channels for these Rydberg series are calculated. The accurate Auger electron energies are compared with high-resolution electron spectroscopy. The results will provide useful data for the identification of spectral lines arising from the Be-like oxygen ions and experimental studies in future work.

Changes of crystal structures, formation energies, electronic band structures and absorptions induced by sulfide ions substituting for oxygen ions in Sr3MgSi2O8-δSδ have been calculated by the first-principles calculation. Through the calculations, it can be found that crystal structures get enlarged with the increasing sulfide ion substituting concentrations. Band structures and densities of states make clear of the compositions of the valence bands and the conduction bands in Sr3MgSi2O8-δSδ. Band gap value of initial Sr3MgSi2O8 without any sulfide ion substitution is about 4.788 eV. Meanwhile, for the Sr3MgSi2O8-δSδ lattices with increasing sulfide ion substitutions, a decreasing trend of band gap values appeared and the minimum band gap gradually decreased to 2.705 eV till δ = 4. This is due to the hybridization of sulfide ion and oxygen ion in Sr3MgSi2O8-δSδ lattice which raised the top of valence band. After the oxygen ions have been totally replaced by the sulfide ion, the band gap grows up to 2.852 eV, which is smaller than that of Sr3MgSi2O8 without sulfide ions substitution. In addition, the calculated absorptions of Sr3MgSi2O8-δSδ gradually shifted from deep UV region to the blue area due to the sulfide ions substitutions. This makes Sr3MgSi2O8-δSδ more suitable for serving as luminescent host materials employed in the UV-pumped white WLEDs.

Li-rich layered oxide cathode materials show high capacities in lithium-ion batteries owing to the contribution of the oxygen redox reaction. However, structural accommodation of this reaction usually results in O–O dimerization, leading to oxygen release and poor electrochemical performance. In this study, we propose a new structural response mechanism inhibiting O–O dimerization for the oxygen redox reaction by tuning the local symmetry around the oxygen ions. Compared with regular Li2RuO3, the structural response of the as-prepared local-symmetry-tuned Li2RuO3 to the oxygen redox reaction involves the telescopic O–Ru–O configuration rather than O–O dimerization, which inhibits oxygen release, enabling significantly enhanced cycling stability and negligible voltage decay. This discovery of the new structural response mechanism for the oxygen redox reaction will provide a new scope for the strategy of enhancing the anionic redox stability, paving unexplored pathways toward further development of high capacity Li-rich layered oxides., Li-rich layered oxide cathodes show high capacities in Li-ion batteries but suffer from structural degradation via O–O dimerization. Here, the authors present local-symmetry-tuned Li2RuO3 with oxygen redox involving a telescopic O–Ru–O configuration avoiding O2 release, enhancing cycling stability.

The Ionospheric Connection Explorer (ICON) mission makes measurements in near-Earth space that provide knowledge of the state of the ionosphere. From the vantage of 575 km altitude in a circular, 27° inclination orbit, it retrieves altitude profiles of the ionospheric density peak in both day and night, characterizing the abundance of oxygen ions in the main ionospheric F-layer. Further, it continuously measures plasma densities and velocities in the immediate vicinity of the observatory. These measurements provide key knowledge required for ICON’s investigations and will be regularly provided data products. They also represent an enhancement to a larger set of ionospheric measurements that are regularly obtained by extant networks. The benefit of this enhancement is realized by ingestion of ICON’s observations into assimilative models developed to provide a realistic state of the ionospheric plasma density as informed by disparate observations. ICON uses the Ionospheric Data Assimilation Four-Dimensional (IDA4D) model for this task and this report demonstrates the assimilation of simulated ICON ionospheric products into this model. The model captures observations in a 3-dimensional tomographic grid, with a temporal component that maintains “memory” of the observations in particular locales between updates, provided by ICON or other sources. The model therefore provides a unifying framework for viewing ICON measurements as part of an integrated whole-ionospheric assimilation.

In this study, the thermal oxidation rate of oxygen ion (O+) implanted 4H–silicon carbide (SiC) was investigated. And the critical breakdown electric field (Ebreakdown) and capacitance–voltage (CV) curve of the grown oxide (SiO2) film were also evaluated. It is found that the thermal SiO2 growth rate on 4H–SiC (0001) face was significantly improved by O+ implantation. Ebreakdown test results showed that the unconsumed amorphous and damaged crystalline layer under the grown SiO2 contained defects leading to an inferior critical breakdown field. Thus, in order to obtain a high-quality SiO2 film, the oxidation process should be designed delicately so that the damaged layer by implantation could be fully consumed.

La2Hf2O7 and La2Mo2O9 as potential electrolytes for solid oxide fuel cells (SOFCs) have been investigated through first-principles calculations to understand the mechanism of ion motion. In La2Hf2O7, three unique types of positions that can form anion-Frenkel (a-Fr) pairs have been screened out and a reasonable continuous diffusion path constructed by these migration sites has also been suggested as the dominant cause of ion conduction. On the other side, excellent ion conductivity in La2Mo2O9 is more based on the short-range disorder induced by mobile structure. The thermodynamic properties comparison of La2Mo2O9 and La2Hf2O7 shows that the formation of a-Fr pairs in La2Mo2O9 will start at lower temperature because of higher degree of structural disorder and less constraints on oxygen ions.

The complex interplay between the influence of oxygen partial pressure and that of rf power on the structural, electrical and optical properties of rf-magnetron-sputtered aluminium-doped zinc oxide, AZO, thin films is illustrated. The dependence of film electrical resistance and interplanar spacing of film crystallites on rf power seems to be different at higher oxygen partial pressure values than at lower ones. Film preparation was performed at room temperature (without extra heating) and low pressure p $$=$$ 0.5 mTorr, varying the rf power density between P $$=$$ 0.57 and 2.83 W $$\hbox {cm}^{-2}$$ at different relative oxygen partial pressure values. An explanation of film properties has been sought in terms of changes in the chemical properties of the films due to the bombardment of the films during film formation with negative oxygen ions.

The reducibility of Au catalysts on CeO2 supports doped with 1 and 2.5 mass% Y2O3 by two types of preparation methods (impregnation and co-precipitation) has been studied by temperature-programmed reduction and compared with that of pure Au/CeO2. The kinetic parameters of reduction were determined simulating each reduction process. The capacities of these catalysts to retain oxygen have been evaluated by temperature-programmed desorption. The catalytic activities in water gas shift reaction were determined measuring CO conversion between 413 and 623 K. The catalytic performances of all these catalysts were explained in terms of mobility of the oxygen ions of the CeO2 lattice.

Experimental studies of the effect of a barrier layer on the kinetics of thermally induced diffusion procesess and phase transformations in a layered Fe–Be syatem are investigated at the energy ~1.6 MeV. Thermal stability of the barrier layer in the Fe:O+ system is validated and a possibility of its use as a subsurface layer for a beryllium coating is demonstrated. For the Cu:O+ system it is shown that the implanted layer in the matrix comes apart already at the annealing temperature ~180°C and could not be used in a copper matrix as a subsurface barrier layer. For the first time, a method is proposed for retardation of diffusion and phase formation processes and realized in a layered iron – beryllium system using an implanted layer of oxygen ions. The sequence and characteristic times of thermally-induced phase-transformation processes taking place in the subsurface layers and in the bulk of the Fe (10 μm) systems: O+ – Be (0.7 μm) – 57Fe (0.1 μm) and Fe (10 μm) – Be (0.7 μm) – 57Fe (0.1 μm) are determined.

Electric-field-driven oxygen ion evolution in the metal/oxide heterostructures emerges as an effective approach to achieve the electric-field control of ferromagnetism. However, the involved redox reaction of the metal layer typically requires extended operation time and elevated temperature condition, which greatly hinders its practical applications. Here, we achieve reversible sub-millisecond and room-temperature electric-field control of ferromagnetism in the Co layer of a Co/SrCoO

An oxygen ion transport model was developed for oxide melts based on V2O5. Within the framework of this model, the values of the parabolic rate constant of catastrophic oxidation of V2O5-deposited copper and the oxygen flux through the slags based on molten V2O5 were calculated and compared with experimental data. The calculated and experimental values are of the same order of magnitude which shows an adequacy of the model.

The oxides with perovskite structure possess abundant physical properties, such as magnetism, dielectricity, photoelectricity, ferroelectricity, etc. The oxygen ions in the perovskite unit cell constitute an octahedral distribution. The deformation or tilting of the special oxygen octahedra structure leads to new performances or properties change. Here, we give a review of the relationship between magnetic and electrical behaviors and oxygen octahedral tilting in several typical perovskite oxides. An understanding of how to tune these properties by controlling the tilting during the sample growth can more effectively guide the design of new structures for high performance and inspiring their potential applications.

Radiation damage in 4H-SiC samples implanted by 70 keV oxygen ion beams was studied using photoluminescence and electron spin resonance techniques. ESR peak of g = 2.0053 and two zero-phonon lines were observed with the implanted samples. Combined with theoretical calculations, we found that the main defect in the implanted 4H-SiC samples was oxygen-vacancy complex. The calculated defect formation energies showed that the oxygen-vacancy centers were stable in n-type 4H-SiC. Moreover, the $$ {\text{V}}_{\text{Si}} {\text{O}}_{\text{C}}^{ 0} $$ and $$ {\text{V}}_{\text{Si}} {\text{O}}_{\text{C}}^{ - 1} $$ centers were optically addressable. The results suggest promising spin coherence properties for quantum information science.

A photoactivated ZnO nanomesh with precisely controlled dimensions and geometries is fabricated by using nanosphere lithography process. The nanomesh structures effectively increase the surface-to-volume ratio to improve the sensing response under the same testing gas. And the periodical nanostructures also increase the effective light path and lead to more efficient light activation for gas sensing. With the increase of the photoinduced oxygen ions by UV illumination, a distinguished sensing response is observed at room temperature. In the optimized case, the sensing response (△R/R0) of the ZnO nanomesh at the butanol concentration of 500 ppm is 97.5%, which is 4.54 times higher than the unpatterned one.

Cluster measurements from 2001 to 2011 provide a unique opportunity to study the characteristics of $\mathrm{O}^{+}$ with full spatial coverage between 4 to $19 \mathrm{R}_{E}$ , especially in the mid-latitude region. Three-dimensional spatial distributions of averaged omnidirectional $\mathrm{O}^{+}$ differential fluxes in three energy channels (E1:40–136 eV; E2:136 eV–3 keV; E3:3–30 keV) during quiet times ( $\mathit{Dst} > -20~\mbox{nT}$ ) are presented in this paper. Comparing the distributions of $\mathrm{O}^{+}$ in three energy channels helps us to better understand the transport and energization of $\mathrm{O}^{+}$ . Consistent with previous studies, it is suggested that during quiet times $\mathrm{O}^{+}$ is heated in the high-altitude cusp and mantle, and part of this heated population is transported through the lobes to the plasmasheet, where it is further heated/accelerated. The distributions presented provide important background information for relevant simulation and observation studies of $\mathrm{O}^{+}$ behavior during storm and non-storm times.

The molar sulphide capacities \( C_{\text{S}}^{'} \) = (mol pct S) (\( P_{{{\text{O}}_{2} }} /P_{{{\text{S}}_{2} }} \))1/2 on four binary systems, MgO-SiO2, CaO-SiO2, MnO-SiO2 and FeO-SiO2 are elucidated so as to compare the magnitudes of the basicities of four metallic oxides and to estimate the temperature dependencies of the basicities of metallic oxides. The enthalpy changes of the reaction 2O− = O + O2−, viz. the silicate polymerization reaction (denoted as \( \Updelta H_{(8)}^{^\circ } \)) have been calculated from the slopes of the log \( C_{\text{S}}^{'} \)vs 1/T curves for four binary silicates. The \( \Updelta H_{(8)}^{^\circ } \) value is considered in the present work to be an index of the basicity of silicate melts. The basicities obtained on the basis of the \( \Updelta H_{(8)}^{^\circ } \) values are in the order MgO < CaO < MnO < FeO, which are determined by two effects; (i) ionicity of chemical bonds between metallic and oxygen ions and (ii) clustering of metallic oxides in silicates. It is also found that the basicity of the FeO-SiO2 system is larger at higher temperatures.

Taking oxygen ion conductor La2Mo2O9, as a base compound, a series of Sn-doped La2Mo2−x Sn x O9−δ, x = 0, 0.01, 0.02, 0.03, 0.05, 0.1, 0.15, 0.2 specimens were prepared and characterized by XRD for phase and crystal structure determination and ac impedance spectroscopy for ac and dc conductivity measurement. We have found that there is slight improvement in overall conductivity of the specimen with x = 0.03 at 800°C compared to the undoped compound at the same temperature. The value of conductivity when extrapolated to 800°C is found to be 0.055 S cm-1 for the specimen with x = 0.03, whereas conductivity of undoped specimen at the same temperature is found to be 0.033 Scm−1.

This paper considers the problem of the \( {\hbox{pO}} = - \log {a_{{{\rm{O}}^{{2 - }}}}} \) scale development and standardization in comparison to the pH standard scale. The approaches describing acid–base equilibrium in oxide melts are analyzed with respect to their applicability to determine the basicity of oxide melts. Procedures for pO measurement and standardization in glass-forming melts are suggested.

The crystal lattice of a complex compound may contain a subsystem of ions with each one possessing two close equilibrium positions (double-well structure). For ex- ample, the oxygen ions in the cuprates form such a subsys- tem. In such a situation it is impossible to separate electronic and local vibrational motions. This leads to a large increase in the effective strength of the electron-lattice interaction, which is beneficial for pairing.

Refractive index and molar refraction of Li2O–, Na2O–, CaO–, and BaO–Ga2O3–SiO2 glasses have been used to test the validity of a structural model of silicate glasses containing Ga2O3 glasses. Ga2O3 enters these types of glass in a similar manner as Al2O3. It is assumed that, for (SiO2/Ga2O3) >1 and (Ga2O3/R2O) ≤1, Ga2O3 associates primarily with modifier oxides to form GaO4 units. The rest of modifier oxide forms silicate units with non-bridging oxygen ions. Silicate structural units have the same factors as found for binary alkali- and alkaline earth silicate glasses. Differences between experimental and model values suggest another structure for (Ga2O3/SiO2) ≥1.

We discuss the ion-ion recombination of positive metal ions and negative oxygen ion in a pulsed gas discharge for realization of the pulsed inversion population mechanism. The metal atom energy levels most populated in this process are estimated. The energy level diagrams with probable transitions for several metal atoms are presented.

Solid electrolyte membrane reactors (SEMRs) have been used to both study and influence catalytic reaction rates. Methane coupling is the reaction most thoroughly and intensively studied in these membrane reactors. In the last 20 years, oxygen ion (O2−), proton (H+) and mixed (O2−-e−, H+-e−) conducting membranes have been tested in order to maximize the conversion of methane to C2 compounds. The present review contains the fundamental operating principles of the various SEMR types and their applications in this reaction. The difficulties that should be overcome in order to promote this SEMR process to an industrial scale are discussed.

In the past ten years a series of developments in the field of materials with dominant oxygen ion conduction introduced a variety of new systems. The most relevant aspect is a shift from ionic transport mechanisms based on the motion of oxygen vacancies, to mechanisms based on mobile oxygen interstitials. In parallel, structures identified with dominant oxygen ion conduction moved from the relatively simple fluorite related ones to more complex materials, namely with the apatite-type and related structures, including coexistence of ionic and covalent bonding. This shift is understood as a major development, opening a wide range of alternative solutions for further exploitation.

The high-temperature oxidation of Ni films electroplated on a steel substrate was studied at 700 and 800°C in air. During oxidation, outward diffusion of Ni and Fe ions and inward diffusion of oxygen ions occurred. NiO formed initially, and as the oxidation progressed, Fe2O3 and NiFe2O4 also formed. The oxidation resistance of Ni films was inferior to that of bulk Ni, which was attributed to the involvement of Fe during oxidation.

Metastable fluorite solid solutions with the nominal composition Bi1.6Mo0.4O3 – x (M = Ca, Ca0.5Sr0.5 , In, Y, La) are prepared by mechanochemical synthesis, and their structure is studied by x-ray diffraction. The oxygen ion conductivity of dense samples prepared by hot pressing is measured in air.

Measurements of the total conduction (450-1030°C) and transport numbers for ions and protons (450-850°C) of titanates ATi0.95M0.05O3 - α (A = Ca, Sr, Ba; M = Mg, Sc) in humid air are performed. Partial conductions (ionic, protonic, oxygen, hole) and their effective energies of activation are determined. The results are discussed within a model of separate transport of proton and oxygen ion.

Electroconductivity of BaCe0.9Nd0.1O3−α was studied as a function of the composition of the H2+H2O+Ar mixture and temperature in the interval from 873 to 1173 K. It was shown that the electroconductivity was independent of PH2 (0.97 to 0.10 atm) and PO2 (10−21 to 10−26 atm), but depended on PH2O (0.08 to 0.005 atm). A mathematical processing of the PH2O dependencies of the electroconductivity, which was performed in terms of a classical model of defect formation in high-temperature proton-conducting solid electrolytes, yielded equilibrium constants of the reaction of water dissolution in BaCe0.9Nd0.1O3−α and mobilities of protons and oxygen ions. The temperature dependencies of these quantities were used to determine the mobility activation energies of protons (Ea=34±7 kJ/mole) and oxygen ions (Ea=72±8 kJ/mole), and also the enthalpy (ΔH=−150±25 kJ/mole) and the entropy (ΔS=153±26 kJ/mole·K) of the reaction of water dissolution in BaCe0.9Nd0.1O3−α.

Correlations between the structural properties of Na2O-CaO-SiO2 glasses characterized by the activity of oxygen ions and the bioactivity were examined by comparing the compositional dependence of the structural parameters calculated on the basis of a thermodynamic consideration with that of the bioactivity. A simple model of characterizing the glass structure by considering the bridging and non-bridging oxygen ions was employed as the first step for this purpose. Further detailed thermodynamic analysis on the anionic constitution in the glass was performed and the compositional dependences of the relative proportions of bridging, non-bridging and free oxygen ions were calculated. The bioactive region corresponded to the compositional region characterized by the higher relative proportion of non-bridging oxygen ions with co-existing an appreciable concentration of bridging oxygen ions, suggesting a possible important role of the non-bridging oxygen ions on the surface chemical process of bone-like apatite layer formation.

The ion-beam apparatus described contains two identical wide-aperture sources of oxygen ions with cold hollow cathodes. One of them serves for depositing a thin layer of the target material on the heated surface of the treated sample by the ion sputtering technique (the target is made of the same material as the sample or a material with similar properties). The second source is used to sputter the obtained structure. The apparatus makes it possible to planarize surfaces of oxide materials by successively filling depressions with a layer of the target material and then sputtering this structure over a depth slightly exceeding the depth of the deposited layer. The deposition–sputtering cycles are repeated with a gradual decrease in the deposited layer thickness.

The density data of Li2O-, Na2O-, CaO- and BaO-Ga2O3-SiO2 glasses have been analyzed. The analysis is based on a structural model predicted from the results of the current spectroscopic investigations. It is assumed that for (R2O or RO)/Ga2O3 = 1 the modifier oxide is used only by the gallate network to form GaO4 tetrahedra without non-bridging oxygen ions. For 1 0.75. This is suggestive for a different distribution of the modifier oxide between the two networks. Empirical relations have been obtained to calculate the density as a function of the composition.

AC-conductivity measurements of BaZr0.90Al0.10O3−δ (where δ describes the number of oxygen ion vacancies per unit cell) in wet and dry N2 have been carried out over the temperature range from 400 to 900 °C. Both atmospheres showed the usual Arrhenius behavior of BaZr0.90Al0.10O2.95. The proton transport number,t H, was also determined from the conductivity measurements of BaZr0.90Al0.10O2.95 in wet and dry N2 and takes up values of 0.97 and 0.78 in the temperature range 400 – 900 °C, respectively.

Electrical conductivity of fluorite phases in the system Y2O3-Ta2O5-MgO has been studied. Y0.8Ta0.2O1.7 fluorite phase, having 15 mol% oxygen ion vacancies, showed the maximum electrical conductivity. Electrical conductivity of Y0.8Ta0.2O1.7 fluorite phase increased linearly with P1/2 HO due to the contribution of protonic conduction in water vapour. The electrical conductivity of the fluorite phase increased more remarkably at lower temperature, 700°C, than at higher temperatures, 800°C and 900°C. The obtained results imply that the protonic conduction greatly contributes to the electrical conductivity of the fluorite phases in the system Y2O3-Ta2O5-MgO in water vapour.

X-Ray absorption spectroscopy is a powerful method of determining local structures in condensed matter. This article reviews the applications of this technique in the study of solid state ionic materials. It begins with an outline of the principles and the experimental procedures followed by a brief overview of some of the recent developments. The bulk of the article is focused on a discussion of examples chosen to emphasise the kinds of problem that can be resolved using the technique. These include studies of local structure in perovskites-structured materials (BaLiF3), proton conducting ceramics (CaZrO3), oxygen ion conductors (BIMEVOX) and semiconducting gas sensors (SnO2). Each system has been selected to show various facets of the technique in terms of the experimental method and data analysis.

Oxygen ion conduction in La0.9Sr0.1Ga1−xMxO3−δ (M=Cr, Fe; x=0 – 0.20), LaGa1−xMxO3−δ (M=Co, Ni; x=0.20 – 0.60), LaGa1−x−yCoxMgyO3−δ (x=0.35 – 0.60; y=0.10 – 0.25) and LaGa0.85−xMg0.15(Nb0.33Mg0.66)xO3−δ (x=0 – 0.20) is reported. At temperatures below 1200 K the ionic conductivity of La(Ga,M)O3−δ (M=Co, Ni) increases with increasing oxygen nonstoichiometry, but is lower than for La(Ga,Mg)O3−δ and (La,Sr)GaO3−δ. Co-doping with Nb and Mg was found to result in decreasing ionic transport in La(Ga,Nb,Mg)O3−δ due to blocking of oxygen sites by Nb5+. Small additions of Fe to the B-site of La0.9Sr0.1GaO3−δ increase the ionic conductivity, whereas substitution of Cr for Ga has the opposite effect. Incorporation of transition metal cations into the Ga site leads to a higher p-type electronic conductivity in all studied perovskites.

The correct nature of high-TC superconductivity is outlined: (i) the cuprates do not superconduct in their cuprate-planes, but in their BaO, SrO, or interstitial-oxygen regions; (ii) doped Ba2YRuO6 and Sr2YRuO6, ruthenates without cuprate-planes, superconduct in their BaO or SrO layers; (iii) the rutheno-cuprates GdSr2Cu2RuO8 and Gd2−zCezSr2Cu2RuO10 have cuprate-planes which do not superconduct, but superconduct in their SrO layers; (iv) LaFeAsO1−xFx superconducts via its oxygen ions, as do related compounds; and (v) the organic compound κ-[BEDT-TTF]2Cu[NCS]2 superconducts along the S chains of the molecule. In YBa2Cu3O7, the superconductivity is consistent with observations by positive muon spin rotation and with analyses indicating an absence of Cu d-band contribution to the superconductivity. Hence only, the BaO layer superconducts. The superconductivity is s-wave in character (not d-wave), once fluxon depinning has been properly accounted for. The superconducting BaO layers are p-type and adjacent to the n-type cuprate-planes. The hole-pairing is not phononic, but Coulombic. Many experiments can be explained by understanding the characteristics of the high-TC mechanism, which contradicts the theories with d-wave superconductivity in the cuprate-planes.

CO2 chemisorption, BET surface area and the degree of reduction of Mo(VI) (e/Mo) have been determined in MoOx/Al2O3 samples, reduced with hydrogen at temperatures between 673 and 1173 K. The free alumina surface figures calculated from the surface area and e/Mo values were identical with those obtained from direct CO2 chemisorption measurements. This identity indicates that all of the oxygen ions of the surface molybdenum-oxygen species block the alumina surface.

1 The dispersion capacity of MoO3 supported on CeO2 is 0.81 rnmo1/100 m2. For samples with MoO3 content is below the dispersion capacity, Mo6+ ions exist in the surface vacancies to form the surface Mo species, and the highly dispersed Mo6+ cations are coordinated by 7 oxygen ions based on the assumption that the CeO2(111) plane is preferentially exposed. 2 The differences of the dispersions between MoO3 on CeO2 and MoO3on ZnO-modified CeO2 indicate that the surface vacancies play an important role in the dispersion of MoO3.

The oxidative coupling of methane over (Bi2O3)1-x(WO3)x (x=0.2, 0.3, 0.4) oxygen ion conductive oxide catalysts irradiated by microwave has been studied. Compared with a conventional heating mode, the temperature of the catalytic bed is much lower with microwave irradiation and there is a change in selectivity favoring the production of C2 products.

In order to investigate the effect of Pr-substitution for Y element in Y123 high-Tc superconductors, Fe57-Mossbauer effect is measured for the samples of Y1-xPrxBa2(Cu1-yFey)3O7-z. The Mossbauer spectrum can be decomposed into 4 sets of doublet spectrum, D1,D2,D3 and D4, and isomer shift (δ) and quadruple splitting (Eq) for each component are obtained. We find that δ on CuO2plane increases with x inY1-xPrxBa2(Cu0.96Fe0.04)3O7-z as well as increase with oxygen reduction in YBa2(Cu0.96Fe0.04)3O7-z while δ in the samples containing Pr decreases by oxygen reduction above z=0.25. These variation of δ can be interpreted by the change of 4p electrons in virtual Fe4p orbital which is induced by hybridization with O2p of the nearest oxygen ions.

The relativistic CI method is used to determine transition probabilities for electric quadrupole transitions between the 1s 2 2s 2 2p 2 (3 P 0,3 P 2,1 D 2) and 1s 2 2p 4 3 P 2 even levels of OIII. The variation of the results with the number of configurations used is discussed, both for the Coulomb and the Babushkin (length) gauge.

Fe3+/Fe2+ ratios were determined for a suite of chromite samples from the Bushveld Complex, South Africa, using57Fe Mossbauer spectroscopy and a ceric sulphate titration method. Two distinctly different types of chromite were identified. Type I chromites have low Fe3+/Fe2+ ratios (between 0.2 and 0.4), and contain 3 cations for every 4 oxygen ions in the chemical formula unit. Type II chromites, on the other hand, have Fe3+/Fe2+ ratios between 0.7 and 1.3, and contain considerably less than 3 cations per 4 oxygen ions in the formula unit. Type II chromites result from the oxidation of type I chromites and can be reduced back to the latter by heating in a gas mixture containing 1% CO and 99% CO2 at 1000 °C.

A complex straggling algorithm is presented to calculate depth-dose distribution of intermediate energy heavy-ion beam. Relative dose Bragg curves of carbon and oxygen ion beams with intermediate energies were computed according to the algorithm above. Comparisons between the relative doses predicted and measured were taken up. The Bragg curves predicted by the complex straggling algorithm show a good agreement with the experimental data. So the reasonableness of this algorithm and its reliability for calculating depth doses were verified. Hence the principle and method to deduce the depth-dose distribution of therapeutic beam was integrated after this algorithm was developed.

The behavior of core 01s levels for low-coordinated (3, 4, 5) oxygen ions on the surface and in the bulk of magnesium oxide has been studied. Mg13O142− and Mg14O132+ clusters have been calculated by the SCF MS Xα method. Binding energies of 1s oxygen states are found to decrease with lowering coordination. This dependence on coordination is attributed to the larger changes in Madelung potential compared to those of pure electron contributions to the binding energy of electrons in oxygen ion. The coordination dependence of ion oxygen charges and relaxation energies is also discussed.

Employing the time-differential perturbed γ-angular correlation technique it is shown that 1s- and2s-electrons of highly stripped16O(3−)-ions have their spin polarized on emergence from magnetized thin Ni- andGd-layers into vacuum. The mean degree of polarization of 2s-electrons is found to be twice as large as for 1s-electrons.

An oxide-ion conductor is a solid oxide material in which the oxygen ions are highly mobile. These materials form the basis of devices that have a huge market potential. The discovery of a new structural family of oxide-ion conductors may lead to fresh design strategies for finding new materials.

The structure of glasses of a local area of the Na2O - Fe2O3 -B2O3 - SiO2 system is studied. The sequence of formation of oxygen-containing tetrahedral groups in the presence of nonbridge oxygen ions is established. Formation of groups of a six-coordinated into cation facilitates crystallization of sodium-boron-silicate glass melts in cooling.

Similar structural patterns have been noticed in the systems La-Cu-O, La-Ni-O and Bi and Tl-containing superconducting oxides. The formation of Ruddlesden-Popper type layers (alternating slabs of rocksalt and perovskite structures) is seen in these oxides which is similar in many respects to what is seen in the system Sr-Ti-O. However, there are some significant differences, for example the rocksalt and perovskite blocks in new superconducting compounds are not necessarily electrically neutral, unlike in the Sr-Ti-O system. It, thus, becomes necessary to create oxygen vacancies in the basic perovskite (figure 1) structure of Bi-containing compounds, when the width of the perovskite slab changes on addition of extra Cu-O planes. Results of our atomistic simulations suggest that these missing oxygen ions allow the Cu-O planes to buckle in Bi-series of compounds. This is also supported by the absence of buckling in the Sr-Ti-O series of compounds and the first member of Bi-containing compounds in which there are no missing oxygen ions. We present additional results on the phase stability of polytypoid structures in La-Cu-O system and defect chemistry of compounds of La-Ni-O system.