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Reducing energy use and improving engine efficiency is a complex task however to date a continued reduction of lubricant viscosity has proved effective. Reducing viscosity decreases hydrodynamic friction and pumping losses however it can also exacerbate boundary friction losses. Detailed and representative component level experimentation is required to understand the effects of viscosity reduction on friction and opportunity for further optimisation. This paper presents a novel motored reciprocating Tribometer which has been developed to measure the friction between complete cylinder liners and three-piece oil control rings. The system holds individual or multiple rings stationary in a bespoke ring holder and reciprocate the cylinder liner thereby replicates the relative kinematics of the components in service. The new design has many operational advantages to identify and benchmark the individual contribution of oil control ring friction including near total isolation of oil ring-cylinder liner bore conjunction, pure rectilinear motion and use of full components without resorting to split liner/ring geometries. The experimental rig is used to measure friction at the three-piece oil control ring- cylinder liner conjunction when lubricated with two low viscosity lubricants. The results show prevalence of mixed regime lubrication across the speeds, temperatures and lubricants investigated. The oil control ring under investigation is shown to operate in mixed regime lubrication and at cold start the introduction of lower viscosity lubricants such as 0W-8 showed higher level of oil control ring-cylinder liner friction in comparison to the 0W-40. The information and experimental facility are of critical use for engine designers when considering the potential contradictory component efficiency behaviour when moving to ultra-low viscosity lubricants.

Optical and structural properties of float-type soda lime silicate (SLS) glasses doped with 0.2 mol % TiO2, ZrO2, HfO2, Nb2O5, Ta2O5, MoO3 or WO3 have been studied. Under UV excitation all d0 doped glasses exhibit broadband visible emission centred between 19,000 cm-1 and 25,000 cm-1 (400nm – 525nm) due to a transition from the 2p orbital of O2- to the metal d0 orbital. Dopant additions lead to shifts in the UV absorption edge to lower energies, with doped glasses having an absorption edge 2,000 cm-1 (~20nm), and in the case of MoO3, 4,000 cm-1 (~40nm), lower than the corresponding undoped glass. Combined UV-Vis absorption and X-band EPR spectroscopy analyses confirm that dopant cations occur in the studied glasses in the expected oxidation states of Ti4+, Zr4+, Hf4+, Nb5+, Ta5+, Mo6+ and W6+, although very low levels of Mo5+ are also observed, as demonstrated by the EPR resonance at g=1.92 (3.7T). The incorporation of the studied dopants into SLS glasses may find applications as cover glasses in photovoltaic (PV) applications, providing UV protection of polymers and solar cell materials in PV units whilst enhancing solar cell efficiency through downconversion / fluorescence of absorbed UV photons with re-emission as visible photons, available for absorption and conversion by the solar cell material.

The neutron diffraction isotopic substitution technique is employed to investigate the environment of Fe3+/Fe2+ cations in a sodium borosilicate glass matrix of composition 0.210Na2O0.18511B2O30.605SiO2. The neutron diffraction data were obtained using the D4c diffractometer at the Institut Laue-Langevin (ILL; Grenoble, France), and were recorded for three samples; the base glass, the base glass incorporating natural Fe2O3 (12 mol.%) and a similar glass containing Fe2O3 enriched in 57Fe. The data are Fourier transformed to yield the real-space total correlation function, T(r), and the first co-ordination shells of the Fe3+/Fe2+ cations are investigated via a peak fit to the isotopic difference correlation function TFe(r). It is concluded that the iron is mainly present as Fe3+ cations, both tetrahedrally and octahedrally co-ordinated by oxygen atoms, plus a small fraction (0.07 ± 0.01) of Fe2+ cations in octahedral co-ordination. The Fe3+ tetrahedral fraction is 0.45 ± 0.10, and appears to exist as FeO4 structural units incorporated into the network of silicate chemical groupings, with their negative charge being balanced by Na+ network-modifying cations. The remaining Fe3+ cations (fraction 0.48 ± 0.10) are thought to be predominantly octahedrally co-ordinated and associatedwith BO33 orthoborate anions in FeBO3 chemical groupings, which become non-stoichiometric due to the reduction of some of the Fe3+ cations to Fe2+.

Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of iron site vacancy concentrations in the iron selenide layers. This iron vacancy concentration is revealed as the only significant compositional variable and as the key parameter controlling the crystal structure and the electronic properties. Single crystal X-ray diffraction, neutron powder diffraction and X-ray absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures as high as 40 K is observed in the hydrothermally synthesised samples when the iron vacancy concentration is low (y < 0.05) and when the iron oxidation state is reduced slightly below +2, while samples with a higher vacancy concentration and a correspondingly higher iron oxidation state are not superconducting. The importance of combining a low iron oxidation state with a low vacancy concentration in the iron selenide layers is emphasised by the demonstration that reductive post-synthetic lithiation of the samples turns on superconductivity with critical temperatures exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer to fill vacancies in the selenide layer, 7 pages supplementary material available from Journal, Inorganic Chemistry 2015

Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO

Lanthanide orthoferrites have wide-ranging industrial uses including solar, catalytic and electronic applications. Here a series of lanthanide orthoferrite perovskites, LnFeO3 (Ln = La; Nd; Sm; Eu; Gd), prepared through a standard stoichiometric wet ball milling route using oxide precursors, has been studied. Characterisation through X-ray diffraction and X-ray fluorescence confirmed the synthesis of phase-pure or near-pure LnFeO3 compounds. 57Fe Mossbauer spectroscopy was performed over a temperature range of 10 K to 293 K to observe hyperfine structure and to enable calculation of the recoil-free fraction and Debye temperature (θD) of each orthoferrite. Debye temperatures (Ln = La 474 K; Nd 459 K; Sm 457 K; Eu 452 K; Gd 473 K) and recoil-free fractions (Ln = La 0.827; Nd 0.817; Sm 0.816; Eu 0.812; Gd 0.826) were approximated through minimising the difference in the temperature dependent experimental Centre Shift (CS) and theoretical Isomer Shift (IS), by allowing the Debye temperature and Isomer Shift values to vary. This method of minimising the difference between theoretical and actual values yields Debye temperatures consistent with results from other studies determined through thermal analysis methods. This displays the ability of variable-temperature Mossbauer spectroscopy to approximate Debye temperatures and recoil-free fractions, whilst observing temperature induced transitions over the temperature range observed. X-ray diffraction and Rietveld refinement show an inverse relationship between FeO6 octahedral volume and approximated Debye temperatures. Raman spectroscopy show an increase in the band positions attributed to soft modes of Ag symmetry, Ag(3) and Ag(5) from La to GdFeO3 corresponding to octahedral rotations and tilts in the [010] and [101] planes respectively.

The capacity of simulated high-level radioactive waste borosilicate glasses to incorporate sulfate has been studied as a function of glass composition. Combined Raman, 57Fe Mossbauer and literature evidence supports the attribution of coordination numbers and oxidation states of constituent cations for the purposes of modelling, and results confirm the validity of correlating sulfate incorporation in multicomponent borosilicate radioactive waste glasses with different models. A strong compositional dependency is observed and this can be described by an inverse linear relationship between incorporated sulfate (mol% SO42−) and total cation field strength index of the glass, Σ(z/a2), with a high goodness-of-fit (R2 ≈ 0.950). Similar relationships are also obtained if theoretical optical basicity, Λth (R2 ≈ 0.930) or non-bridging oxygen per tetrahedron ratio, NBO/T (R2 ≈ 0.919), are used. Results support the application of these models, and in particular Σ(z/a2), as predictive tools to aid the development of new glass compositions with enhanced sulfate capacities.

Radionuclide and heavy metal pollution are the main concerns for the environment nowadays as thousands of waste sites around the world pose a serious threat to all living organisms and humans, in particular. Therefore, the focus of this study is on the development of novel-sensing technologies for the detection of radionuclides and heavy metals in water utilizing microorganisms. Several optical methods, i.e., fluorescence microscopy, fluorescence spectroscopy, and UV-vis spectrophotometer were exploited here for studying the effect of γ-radiation (from Co-57 source) and one of the heavy metal ions (Cd+2) on two types of bacteria, namely Escherichia coli (E. coli) and Deinococcus radiodurans (D. radiodurans). All three optical methods gave consistent and correlated results in regards to the gamma radiation. An exponential decay in bacterial counts with the increase in γ-radiation dose was observed in E. coli bacteria samples, while D. radiodurans bacteria appeared to be much less affected by γ-radiation and showed even a small increase in the bacteria counts at low-radiation doses followed by a rather moderate decay at intermediate and high doses. The effect of Cd2+ on bacteria is more complex, however, and the method of fluorescence microscopy gave the most reliable account in live bacteria concentration. Both E. coli and D. radiodurans bacteria showed similar effects of a moderate decay of bacteria counts with the increase in CdCl2 concentration. Comparative analysis of the results obtained shows a clear possibility of pattern recognition of the presence of γ-radiation and heavy metals using the above two bacteria.

Mossbauer spectroscopy was used to examine Fe-containing microporous materials zeolite X and AlPO-5 designed for the reduction of Cr(VI) to Cr(III) and Cr(III) uptake. XRD, XRF, EPR and XPS were used to provide supporting information. AlPO-5 was found to only incorporate inactive Fe(III), whilst Fe(II) and Fe(III) were identified in zeolite X across a distribution of sites. Fe coordinates to oxygen atoms belonging to both water molecules and framework positions. EPR confirmed these findings and showed how the site distribution narrows upon dehydration. XPS showed that a distribution of Fe sites exists at the sample surface. Mossbauer spectroscopy was also used to track oxidation and reduction processes in Fe-zeolite X. Over time, gradual Fe oxidation takes place in air-exposed samples. Reduction under hydrogen flow increases the populations of low oxidation state Fe; as the reaction time increases, Fe(II) populations first increase, then decrease as Fe(0) is evolved.

Reaction of the Ruddlesden-Popper phases Sr2Fe(0.5)Ru(0.5)O4 and Sr3(Fe(0.5)Ru(0.5))2O7 with CaH2 results in the topochemical deintercalation of oxide ions from these materials and the formation of samples with average compositions of Sr2Fe(0.5)Ru(0.5)O(3.35) and Sr3(Fe(0.5)Ru(0.5))2O(5.68), respectively. Diffraction data reveal that both the n = 1 and n = 2 samples consist of two-phase mixtures of reduced phases with subtly different oxygen contents. The separation of samples into two phases upon reduction is discussed on the basis of a short-range inhomogeneous distribution of iron and ruthenium in the starting materials. X-ray absorption data and Mössbauer spectra reveal the reduced samples contain an Fe(3+) and Ru(2+/3+) oxidation state combination, which is unexpected considering the Fe(3+)/Fe(2+) and Ru(3+)/Ru(2+) redox potentials, suggesting that the local coordination geometry of the transition metal sites helps to stabilize the Ru(2+) centers. Fitted Mössbauer spectra of both the n = 1 and n = 2 samples are consistent with the presence of Fe(3+) cations in square planar coordination sites. Magnetization data of both materials are consistent with spin glass-like behavior.

Reaction of the appropriate Sr3(M(0.5)Ru(0.5))2O7 (M = Ti, Mn, Fe), n = 2, Ruddlesden-Popper oxide with CuF2 under flowing oxygen results in formation of the oxide-fluoride phases Sr3(Ti(0.5)Ru(0.5))2O7F2, Sr3(Mn(0.5)Ru(0.5))2O7F2, and Sr3(Fe(0.5)Ru(0.5))2O(5.5)F(3.5) via a topochemical anion insertion/substitution process. Analysis indicates the titanium and manganese phases have Ti(4+), Ru(6+) and Mn(4+), Ru(6+) oxidation state combinations, respectively, while Mössbauer spectra indicate an Fe(3+), Ru(5.5+) combination for the iron phase. Thus, it can be seen that the soft fluorination conditions employed lead to formation of highly oxidized Ru(6+) centers in all three oxide-fluoride phases, while oxidation states of the other transition metal M cations remain unchanged. Fluorination of Sr3(Ti(0.5)Ru(0.5))2O7 to Sr3(Ti(0.5)Ru(0.5))2O7F2 leads to suppression of magnetic order as the fluorinated material approaches metallic behavior. In contrast, fluorination of Sr3(Mn(0.5)Ru(0.5))2O7 and Sr3(Fe(0.5)Ru(0.5))2O7 lifts the magnetic frustration present in the oxide phases, resulting in observation of long-range antiferromagnetic order at low temperature in Sr3(Mn(0.5)Ru(0.5))2O7F2 and Sr3(Fe(0.5)Ru(0.5))2O(5.5)F(3.5). The influence of the topochemical fluorination on the magnetic behavior of the Sr3(M(0.5)Ru(0.5))2O(x)F(y) phases is discussed on the basis of changes to the ruthenium oxidation state and structural distortions.

Fe Mössbauer spectra have been recorded from the hexagonal (6H)- and trigonal (15R)- modifications of BaFeOF and are compared with those previously recorded from the cubic form of BaFeOF. The spectra, recorded over a temperature range from 15 to 650 K show that all of the iron in all the compounds is in the Fe state. Spectra from the 6H- and 15R-modifications were successfully fitted with components that were related to the Fe(1) and Fe(2) structural sites in the 6H variant and to the Fe(1), Fe(2) and Fe(3) structural sites in the 15R form. The magnetic ordering temperatures were determined as 597 ± 3 K for 6H-BaFeOF and 636 ± 3 K for 15R-BaFeOF. These values are surprisingly close to the value of 645 ± 5 K determined for the cubic form. The magnetic interactions in the three forms are compared with a view to explaining this similarity of magnetic ordering temperature.

We thank EPSRC for funding, STFC for providing neutron facilities and Diamond Light Source for provision of synchrotron facilities. We thank Dr Chiu Tang for assistance at Diamond and Dr A. Kusmartseva (University of Edinburgh) for assistance with the SQUID measurements. FDM thanks the Royal Society for a Research Fellowship. The hexagonal ferrites MFeO3 (M=Y, Yb, In) have been studied using a combination of neutron and X-ray powder diffraction, magnetic susceptibility, dielectric measurements and 57Fe Mössbauer spectroscopy. This study confirms the previously reported crystal structure of InFeO3 (YAlO3 structure type, space group P63/mmc), but YFeO3 and YbFeO3 both show a lowering of symmetry to at most P63cm (ferrielectric YMnO3 structure type). However, Mössbauer spectroscopy shows at least two distinct Fe sites for both YFeO3 and YbFeO3 and we suggest that the best model to rationalise this involves phase separation into more than one similar hexagonal YMnO3-like phase. Rietveld analysis of the neutron diffraction data was carried out using two hexagonal phases as a simplest case scenario. In both YFeO3 and YbFeO3, distinct dielectric anomalies are observed near 130 K and 150 K, respectively. These are tentatively correlated with weak anomalies in magnetic susceptibility and lattice parameters, for YFeO3 and YbFeO3, respectively, which may suggest a weak magnetoelectric effect. Comparison of neutron and X-ray powder diffraction shows evidence of long-range magnetic order in both YFeO3 and YbFeO3 at low temperatures. Due to poor sample crystallinity, the compositional and structural effects underlying the phase separation and possible magnetoelectric phenomena cannot be ascertained. Postprint

Modified iron phosphate glasses have been prepared with nominal molar compositions [(1�x)�(0.6P2O5–\ud 0.4Fe2O3)]�xRySO4, where x = 0–0.5 in increments of 0.1 and R = Li, Na, K, Mg, Ca, Ba, or Pb and y = 1 or 2. In\ud most cases the vast majority or all of the sulfate volatalizes and quarternary P2O5–Fe2O3–FeO–RyOz\ud glasses or partially crystalline materials are formed. Here we have characterized the structure, thermal\ud properties, chemical durability and redox state of these materials. Raman spectroscopy indicates that\ud increasing modifier oxide additions result in depolymerization of the phosphate network such that the\ud average value of i, the number of bridging oxygens per –(PO4)– tetrahedron, and expressed as Qi,\ud decreases. Differences have been observed between the structural effects of different modifier types\ud but these are secondary to the amount of modifier added. Alkali additions have little effect on density;\ud slightly increasing Tg and Td; increasing a and Tliq; and promoting bulk crystallization at temperatures\ud of 600–700 �C. Additions of divalent cations increase density, a, Tg, Td, Tliq and promote bulk crystallization\ud at temperatures of 700–800 �C. Overall the addition of divalent cations has a less deleterious effect\ud on glass stability than alkali additions. 57Fe Mössbauer spectroscopy confirms that iron is present as Fe2+\ud and Fe3+ ions which primarily occupy distorted octahedral sites. This is consistent with accepted structural\ud models for iron phosphate glasses. The iron redox ratio, Fe2+/RFe, has a value of 0.13–0.29 for the\ud glasses studied. The base glass exhibits a very low aqueous leach rate when measured by Product Consistency\ud Test B, a standard durability test for nuclear waste glasses. The addition of high quantities of\ud alkali oxide (30–40 mol% R2O) to the base glass increases leach rates, but only to levels comparable with\ud those measured for a commercial soda-lime-silica glass and for a surrogate nuclear waste-loaded borosilicate\ud glass. Divalent cation additions decrease aqueous leach rates and large additions (30–50 mol%\ud RO) provide exceptionally low leach rates that are 2–3 orders of magnitude lower than have been measured\ud for the surrogate waste-loaded borosilicate glass. The P2O5–Fe2O3–FeO–BaO glasses reported here\ud show particular promise as they are ultra-durable, thermally stable, low-melting glasses with a large\ud glass-forming compositional range.

Mossbauer spectroscopy and X-ray absorption spectroscopy (XAS) have been used to obtain information on the redox and coordination of iron in glasses made by the vitrification of simulated and actual sewage sludge combustion ashes. Mossbauer spectra have been deconvoluted using three extended Voigt-based profiles to allow quantitative analysis of multiple Fe3 + coordination environments. XAS Fe pre-K-edge absorption peaks have been analysed and fitted against reference standards to yield complementary analyses and provide validation of the Mossbauer results. Correlations are noted between the iron redox and the Fe3 + coordination. Tetrahedral Fe3 + is much more likely to take part in any redox reaction whilst octahedral Fe3 + appears to be more resistant to reduction to the ferrous state. Results from XAS also suggest that Fe2 + ions occupy both four- and six-fold coordination environments. Neither technique has provided any clear evidence for the existence of Fe2 + or Fe3 + in five-fold symmetry in the glasses studied.

57FeM¨ossbauer spectroscopy has provided precise and accurate iron redox ratios Fe2+/Fe3+ in ilmenite, FeTiO3, found within kimberlite samples from the Catoca and Camatxia kimberlite pipes from N.E. Angola. Ilmenite is one of the key indicator minerals for diamond survival and it is also one of the iron-bearing minerals with iron naturally occurring in one or both of the oxidation states Fe3+ and Fe2+. For this reason it is a good indicator for studying oxygen fugacities (fO2) in mineral samples, which can then be related to iron redox ratios, Fe2+/Fe3+. In this paper we demonstrate that the oxidation state of the ilmenite mineral inclusion from sampled kimberlite rock is a key indicator of the oxidation state of the host kimberlite assemblage, which in turn determines the genesis of diamond, grade variation and diamond quality. Ilmenite samples from the two different diamondiferous kimberlite localities (Catoca and Camatxia) in the Lucapa graben, N.E. Angola, were studied using M¨ossbauer spectroscopy and X-Ray Diffractometry, in order to infer the oxidation state of their source regions in the mantle, oxygen partial pressure and diamond preservation conditions. The iron redox ratios, obtained using M¨ossbauer spectroscopy, show that the Catoca diamond kimberlite is more oxidised than kimberlite found in the Camatxia pipe, which is associated within the same geological tectonic structure. Here we demonstrate that 57Fe M¨ossbauer spectroscopy can assist geologists and mining engineers to effectively evaluate and determine whether kimberlite deposits are economically feasible for diamond mining.

The structural changes that occur in a FeOx/γ-Al2O3 catalyst during the dehydrogenation of ethylbenzene in a fluidized CREC Riser Simulator have been investigated. Chemical and morphological changes are observed to take place as a result of reaction. Electron microscopy reveals the formation of needle-like alumina structures apparently enclosing iron oxide particles. The formation of such structures at relatively low temperatures is unexpected and has not previously been reported. Additionally, X-ray diffraction and Mössbauer spectroscopy confirmed the reduction of the oxidation state of iron, from Fe2O3 (haematite) to Fe3O4 (magnetite). Iron carbides, Fe3C and ɛ-Fe2C, were detected by electron microscopy through electron diffraction and lattice fringes analysis. Carbon deposition (coking) on the catalyst surface also occurs. The observed structural changes are likely to be closely correlated with the catalytic properties of the materials, in particular with catalyst deactivation, and thereby provide important avenues for future study of this industrially important reaction. Fe2O3/Al2O3 catalyst undergoes chemical and morphological changes during ethylbenzene dehydrogenation forming Al2O3 needles which appear to contain reduced Fe3O4 particles. Fe3C also forms during reaction.

Four new phases of general formula, Li11RE18M4O39−δ: REM = NdAl, NdCo, SmCo, SmFe, have been synthesised\ud and characterised. The NdAl phase, and probably the others, is isostructural with the NdFe analogue,\ud but some cation disorder and partial site occupancies prevent full structural refinement of powder\ud neutron diffraction data. The NdCo phase also forms a solid solution with variable Li content (and charge\ud compensation by either oxygen vacancies or variable transition metal oxidation state). The NdAl phase is a\ud modest conductor of Li+ ions whereas the other three phases are electronic conductors, attributed to\ud mixed valence of the transition metal ions. Subsolidus phase diagrams for the systems Li2O–Nd2O3–\ud Al2O3, ‘CoO’ have been determined and an additional new phase, LiCoNd4O8, which appears to have a\ud K2NiF4-related superstructure, identified.

The effects of doping 60 P2O5–40 Fe2O3 (mol%) glasses with 5–10 mol% SiO2, Al2O3 or B2O3 on their thermal stability, iron environments and redox were investigated. Thermal stability improved markedly with 5% dopant addition in the order Al2O3 > SiO2 > B2O3 ≫ base glass. Solubility of pro rata additions when melted at 1150 °C was 5–10% SiO2, 10% B2O3. It was possible to dissolve 5% Al2O3 by replacing Fe2O3. These additions generally had little effect on dilatometric measurements and iron environments, however the Fe2+/ΣFe redox ratio increased in the order base glass < Al2O3 < SiO2 < B2O3. This behaviour was broadly consistent with the effects of glass basicity. The increased thermal stability of these glasses may improve their suitability for applications such as waste immobilisation or sealing.

Preliminary studies of sulphate solubility, redox, composition, refractory corrosion and density of 60P2O5–40Fe2O3 (molar percent) glasses are presented. Techniques included Mossbauer spectroscopy and energy-dispersive X-ray spectroscopy. Sulphate solubility of the glass was very low, only 0.01 wt.% SO3. Iron (II) sulphate batch addition resulted in a more reduced glass than a sulphate-free batch. Redox, considered independently of temperature, had no effect on refractory corrosion or melt volatilisation in the range studied. No differences were detected in refractory corrosion using alumina or mullite crucibles. Higher oxygen partial pressure had no effect on iron valence. Values, trends and conclusions relating to density, molar volume, iron environment and iron coordination in these glasses were consistent with the accepted view.

Various iron-containing phosphate glasses were investigated by Mossbauer spectroscopy. Iron was found to occur predominantly as Fe3+ in all glasses, and largely occupied sites with distorted octahedral coordination for both redox states. Using a base glass of nominal composition 60 P2O5–40 Fe2O3 (mol%), stepwise molar replacement of Fe2O3 by (0.67 Na2O × 0.33 Al2O3) increased the redox ratio, Fe2+/ΣFe, from 0.13 at 40% Fe2O3 to 0.25 at 10% Fe2O3. The centre shift increased and quadrupole splitting decreased by up to ∼20% over this range, interpreted as a decrease in the average distortion of Fe sites from cubic symmetry, and an increase in average iron coordination. Literature revealed that recoil-free fraction ratio f (Fe3+) / f (Fe2+) ≈ 1.3 in iron phosphate glasses, and this was considered when assessing redox. Mossbauer parameters of these and other glasses demonstrated a combination of structural stability and compositional flexibility which makes them so suitable for waste immobilisation.

Waste filter cakes from two metal finishing operations were heat treated and vitrified. Substantial weight loss during heating was due to emission of water, volatile sulphur-rich and chlorine-rich compounds, and the combustion of carbonaceous components. Estimations of COx, SOx and HCl emissions were based on chemical analyses. Upon cooling from molten, one sample remained amorphous but all others partially crystallised. Crystalline nature was dependent upon waste composition and the level of P2O5 addition. Thermal stabilities of the waste forms were good, but less so than MW, a borosilicate glass developed for its high temperature stability. Mossbauer and FTIR analyses showed that iron environments in the different vitrified waste forms were very similar. Iron was present predominantly as Fe3+, although the exact redox ratio varied slightly between waste forms. Iron in both redox states occupied distorted octahedral coordination polyhedra with similar levels of site distortion. Phosphate networks in the vitreous materials were highly de-polymerised, consisting largely of (PO4)3− monomer and (P2O7)2− dimer units. This explained the high chemical durability of these waste forms and their structural insensitivity to compositional change, underlining their suitability as hosts for the immobilisation of toxic and nuclear wastes.

A systematic study has been made to characterise a pulsed RF discharge used for the plasma treatment of polymers. Using a time-resolved Langmuir probe and a time-resolved retarding field energy analyser (RFA) the electron temperature and density, plasma potential, ion energy distribution function (IEDF) and electron energy distribution function (EEDF) has been measured. The source was pulsed for a range of frequencies from 100 Hz to 1 KHz at various duty cycles from 20 to 80%. A base pressure less than 10 −5 Torr was achieved to decrease the level of impurities in the chamber. The electron temperature ( T e ) decreases from 5 eV to less than 0.5 eV in afterglow. The cooling rate of T e depends on the pressure, power and duty cycle. By pulsing a biased grid synchronously with the pulsed RF, ions are selected from different time of the plasma and allowed to impinge on a polymer surface. Modified oxygen to carbon (O/C) ratio in the upper layer of polystyrene has been measured by X-ray photon emission spectroscopy (XPS) for different energy and flux of plasma ions. These results show that the treatment is either insensitive to ion energy or dominated by the UV in the discharge.

We describe the development and diagnosis of a two-stage plasma discharge in which a source plasma is separated from a secondary process plasma by a fine mesh. Through the application of a DC bias potential to the mesh the electron temperature T e and mean ion bombarding energy E i to an electrically isolating substrate can be well controlled in the secondary discharge. Electrical probe and retarding field analyser measurements have shown that T e and E i can be varied in the range 0.2–4 and 1–26 eV, respectively, and are found to be spatially uniform. Using this system, the bombarding ion flux can also be varied in the range from 10 17 to 10 19 m −2 s −1 , independently of the ion energy through the combined variation of the primary discharge power, and pressure and substrate location. These types of plasmas may find applications in the controlled plasma modification of materials through tailoring of the ion energy and flux.

We present a simple technique for obtaining the time-resolved ion energy distribution function (IEDF) at a boundary in pulsed plasmas using a commercial quadrupole mass energy analyser. In this technique, ions are extracted from the plasma at selected parts of the pulse cycle, through the synchronized electrical biasing of a grid assembly attached to the barrel of the instrument, forming an electrostatic shutter. This sampling method has the advantage over the normal technique of electronically gating the detected ion signal to achieve time resolution, since the IEDFs can be obtained even when the ion flight time through the instrument (typically 100 µs) is greater than the pulse period or the characteristic time of transients in the plasma under investigation. The arrangement allows us therefore to diagnose plasmas pulsed at high frequencies (≥10 kHz). Presently, a time resolution of 4 µs can be obtained, limited only by the driving electronics design. The technique has been tested on a DC magnetron discharge operated in argon. The plasma was pulsed at a low frequency of 2 kHz, but with a discharge voltage waveform containing fast transients (on the µs time scale or faster). The results show clearly the evolution of the IEDFs during the pulse, responding to these fast transients with a significant number of ions created at plasma potentials above 140 V. These time-evolved IEDFs cannot be obtained using the conventional, manufacturer's time-resolved method for this instrument. However, the new technique does introduce a small distortion in the measured IEDFs at energies above 120 eV, which is always observed, irrespective of the position of the shutter window during the pulse. This is due to the transient nature of the discriminating grid bias used in the electrostatic shuttering. Its effects and possible elimination are discussed.

The formation of intermetallic phases influences the properties of commercial alloys. CEMS can be used to reveal the presence of Fe-Sn intermetallics at the interface on tinplated steels. The work presented investigates the sensitivity of CEMS to detect intermetallics. Varying amounts of Fe-Sn intermetallics have been identified by CEMS having been produced by heat treating samples of tinplated steel at selected temperatures and times. The effect of surface roughness of the substrate on the Mossbauer signal has also been investigated. The intermetallic formation was found to reach a limiting value with increased heat treatment. Using CEMS, intermetallic formation was observed at temperatures as low as 190°C. Sample roughness was found to affect intermetallic formation and their observation using CEMS and GA-XRD.

Phthalocyanines are established gas sensitive materials. We have successfully recorded backscatter conversion electron Mossbauer spectra (CEMS) of iron(II) phthalocyanine. Further, we have shown that the introduction of nitrogen dioxide, a typical analyte for these materials, into the detector system can be achieved without deleterious effects. The method allows surface sensitive spectra of these materials to be recorded under normal sensor operating conditions of temperature and pressure. The high vacuum conditions of other surface sensitive techniques used to study materials of this type are not required by this method.

Poland), being the large Ediacaran continental igneous province, that covers an area of 200 000 km 2 in the western margin of East European Craton. The series is underlain by the Cryogenian terrigenous Polesie Series with doleritic sills and dikes. The Volhynian Series consists of the rock beds belonging to the three volcanic cycles with dierent ratios of flood basalts to pyroclastics. The aim of the study was recognition of primary and secondary Fe-bearing minerals, particularly Fe- and Fe-Ti oxides as well as determination of iron oxidation state, that is an important tool in the search for native copper deposits in these rocks. For Mossbauer studies the following rock samples were chosen: the Polesie Series dolerites, the Volhynian Series basalts from the Ukrainian quarries

The microstructure of TiAlN coatings deposited by reactive unbalanced magnetron (UBM) sputtering after substrate bombardment with Cr ions, generated by a cathodic arc, and compositional changes of the ferritic steel substrate have been investigated for different bias voltages ( U b ) during the Cr bombardment. Analysis was carried out using cross-sectional transmission electron microscopy (XTEM) and conversion electron Mossbauer spectroscopy (CEMS). The aim of the Cr bombardment is a substrate sputter cleaning effect. This is achieved when a bias voltage of −1200 V is applied. In this case subsequent UBM deposition of TiAlN leads to the growth of dense coatings exhibiting local epitaxy. For lower bias voltages CEMS indicates Cr deposition resulting in an open columnar structure of the subsequently grown TiAlN film, although small areas with oriented growth can still be observed.

57Fe conversion electron Mossbauer spectroscopy has been used to investigate the intermetallic phases near the surface of a D.C. cast aluminium ingot. The CEMS data is used with SAAES (selected area Auger electron spectroscopy) and SAXPS (selected area X-ray photoelectron spectroscopy) data to propose a model of the surface region above the grain boundaries.

Direct-chill (D.C.) casting is a widely used technique for casting industrial aluminium alloy ingots. Commercial purity alloys contain small amounts of iron and silicon. During casting, intermetallic phases are formed inter-dendritically from the final liquid to solidify. Since the solidification rate varies substantially with position in the ingot various phases can form, ranging from the equilibrium phase Al{sub 3}Fe{sub 4}, to increasingly metastable phases, such as Al{sub 6}Fe, Al{sub x}Fe, Al{sub m}Fe or alpha-AlFeSi, as the solidification rate increases. The phases formed may influence the ease of processing and the final gauge properties of the material. Fe Moessbauer spectroscopy has been used previously to identify the intermetallic phases in situ in aluminium from Bridgman grown model alloys. Also variable temperature studies have been carried out on the phases extracted from the alloys by butanol dissolution. The work reported in this paper demonstrates how the Moessbauer data obtained from the previous studies can now be used to identify and quantify the proportion of different phases formed in ingots prepared by direct-chill casting and subsequent heat treatments.

Pure intermetallic phases Al13Fe4, Al6Fe, AlmFe and AlxFe have been extracted from Bridgman grown model aluminium–iron binary alloys by dissolving the aluminium matrix in butanol. Each phase has a distinct Mossbauer spectrum and variable temperature 57Fe Mossbauer studies have enabled the Debye temperature $$\theta _D $$ of each phase to be determined. Hence, the variation of the recoil‐free fraction f with temperature is determined for each phase. From this information it is possible to measure the proportion of each phase, either when the phases are extracted or in situ in aluminium. The results obtained can be used in the characterisation of industrially cast aluminium.

A critical stage of the combined steered arc and unbalanced magnetron process is the titanium ion etch which improves the adhesion of the TiN coating. This study uses Conversion Electrom Mossbauer spectroscopy (CEMS) to investigate the phases that are formed when steel substrates are given a metal ion etch as a pretreatment prior to the deposition of ceramic coating of the type TiC/N. To detect iron containing phases of a thickness in the order of nanometers it has been necessary to enrich the substrates with the Mossbauer isotope 57Fe. The enriched substrates have been treated by a range of Ti ion etch processes and then characterised by CEMS. This technique has identified a number of phases, including the FeTi phase.

The deposition of ceramic coatings of the type TiC/N on steels enhances the surface properties of the coated substrate. A critical stage in the Arc Bond Sputtering TM process, using the combined steered arc and unbalanced magnetron, is the titanium ion etch which improves the adhesion of the TiN coating to the substrate. Conversion electron Mossbauer spectroscopy (CEMS) has provided evidence that the ion etch pretreatment involves the formation of phases including FeTi at a narrow interface region. To detect these phases it has been necessary to enrich substrates with the Mossbauer isotope 57 Fe. The enriched 57 Fe substrates have been treated by a range of ion etch processes and then characterized by CEMS. The role of the FeTi in improving coating–substrate adhesion is not fully understood but work is currently underway using XTEM, SNMS, Auger electron spectroscopy, etc., with CEMS to gain an understanding of the mechanisms involved.

The deposition of hard coatings of the type TiC/N on steels enhances the surface properties of the coated substrate. Steel substrates have been pre-heated by the Arc Bond Sputtering process (ABS™), which uses a combined steered arc and unbalanced magnetron arrangement. A critical stage of the ABS process is the titanium ion etch which improves the adhesion of the TiN coating to the substrate. This work uses conversion electron Mossbauer spectroscopy (CEMS) to study the phase formations in the near surface region of mild steel substrates after various Ti ion etch pre-treatments using the steered arc discharge within the ABS process. The work has also investigated a second method using a Balzers BAI 640R coating unit. Appropriate enrichment using the Mossbauer isotope 57Fe has been used, enhancing the interfacial sensitivity of the CEMS technique to detect and identify phases formed by various ion etch processes. The results for the ABS pre-treatments indicate that oxides and carbonitrides that may be formed during the initial stages of the Ti ion etch, are removed after a longer etch. For a conventional 10-min Ti ion pre-treatment a significant formation of both a crystalline FeTi and a Te-rich amorphous phase occurs. The existence of the crystalline phase has also been confirmed by X-ray diffraction. For comparison, samples that had been pre-treated and coated in the Balzers process show some evidence of the FeTi amorphous phase and the development of an iron carbonitride, often identified as ϵ−Fe2–3(CN).

Sr3 (Ti0.5Ru0.5)2O7F2 (I), Sr3 (Mn0.5Ru0.5)2O7F2 (II), and Sr3 (Fe0.5Ru0.5)2O5.5F3.5 (III) are obtained from Sr3(M0.5Ru0.5)2O7 (M: Ti, Mn, Fe) by a solid state topochemical anion insertion/substitution process using CuF2 under flowing O2 (250 °C, 3 times 8 h).

During the semi-continuous casting of aluminium alloy ingots, the solidification rate varies substantially with position in the ingot. For commercial purity alloys, which contain small amounts of iron and silicon, intermetallic phases are formed inter-dendritically from the final liquid to solidify, and comprise typically 1% of the microstructure. The development in the work reported in this paper is that the phases of interest have been extracted from super-purity based, Bridgman Grown model aluminium-iron binary alloys by dissolving the aluminium matrix in butanol. This has the advantage of providing the pure phase and thus increases the proportion of iron (and Fe-57) which gives an improved signal to noise ratio for Moessbauer spectroscopy. Using phases extracted in this way, detailed variable temperature Moessbauer studies have been carried out on Al{sub 13}Fe{sub 4} and Al{sub 6}Fe. The variation with temperature of the isomer shift and absorption area were obtained. This enabled the recoil-free fractions of the two phases to be determined. With this information it was then possible to determine the proportion of Al{sub 13}Fe{sub 4} and Al{sub 6}Fe in an extracted sample containing both phases, and in a rod of the aluminium containing both phases in situ.

Variable-temperature 57Fe Mossbauer spectroscopy, thermogravimetry (TG), powder X-ray diffraction (PXRD) and temperature-programmed solid insertion probe mass spectrometry (TP-SIP-MS) have been used to study the interaction of dimethylaminomethylferrocene (DMAMF) with Westone-L (WL), a low iron montmorillonite. The hydrochloride salt of DMAMF, (ferrocenylmethyl)dimethylammonium chloride (FMDMACl), was prepared and studied both prior and subsequent toexchange on the interlamellar sites of WL. X-Ray diffraction confirmed that the FMDMA+ cations were incorporated between the clay lamellae and the observed spacing of 15.1 A was thermally stable up to 200 °C in air. TP-SIP-MS indicated that a small proportion of the incorporated metallocene was volatilised at temperatures below 400 °C, but that the majority decomposed via loss of cyclopentadienyl ligands leaving the metal centre between the sheets. A similar thermal degradation path was observed for DMAMF on aluminium pillared clay (Al-PILC). 57Fe Mossbauer spectroscopy revealed that the FMDMA+ cation occupied a similar environment in the chloride salt, FMDMA+–WL and DMAMF–Al-PILC insofar as the isomer shift, 6, and quadrupole splitting, Δ, of the incorporated metallocene were essentially the same in all complexes and virtually identical to that observed for FMDMACl(δ= 0.34 mm s–l, δ= 2.32 mm s–l at 300 K). The values for the Debye temperature θ, and recoil-free fraction f determined from variable-temperature 57Fe Mossbauer spectroscopy, were typically 140 K and 0.12, respectively, for FMDMACl and FMDMA+–WL, thus confirming the similar environment occupied by the cation in the chloride salt and in WL. In contrast, the corresponding values for DMAMF–A1-PILC were 118 K and 0.06, respectively, indicating that the the metallocene enjoyed much greater freedom in the galleries of the Al-PILC which exceed the dimensions of the metallocene compared to FMDMA+-WL where the organoiron cation itself determines the layer separation.

The UMIST duoplasmatron provides high plasma particle emission rates in excess of 5*1017 S-1 and energetic stream conditions. Plasma ions are ejected with supersonic velocities. The expansion of the emerging hydrogen plasma and subsequent ion acceleration to mean energies of over 130 eV are modelled using a simple fluid description. A technique for exchanging hydrogen ions for argon in the expanding beam is demonstrated, giving energetic, heavy-ion stream conditions. The potential for using the duoplasmatron as a source of ions for direct sputtering of insulating materials is discussed.

Variable-temperature 57Fe Mossbauer spectroscopy, thermogravimetry and powder X-ray diffraction have been used to study the cations tricarbonyl(η5–2,4-dimethylcyclohexadienyl)iron(1+) and tricarbonyl(η5–2-methoxycyclohexadienyl)iron(1+) as both the hexafluorophosphate salts (A1 and A2, respectively) and when cation-exchanged onto the interlamellar sites of Westone-L (W-L), a low-iron montmorillonite (denoted A1-W-L and A2-W-L, respectively). A combination of thermogravimetry, total carbon analysis and X-ray fluorescence analysis for iron indicated that 40% of the available exchange sites on W-L were occupied by the cyclohexadienyl cations. The isomer shift, δ, and quadrupole splitting, Δ, of both A1 (δ= 0.02 mm s–1; Δ= 1.56 mm s–1) and A2 (δ= 0.02 mm s–1; Δ= 1.47 mm s–1) were unaffected by incorporation of the cations into the interlamellar environment. The hexafluorophosphate salts, A1 and A2, exhibited similar Debye temperatures, θD, and recoilless fractions, f, of 160 ± 2 K and 0.61, respectively, indicating that both iron moities enjoyed the same amount of freedom in the parent salt. In contrast, the values of θD and f for A2-W-L (140 K and 0.54, respectively) were both higher than for A1-W-L (131 K and 0.49), indicating that A2 was held more tightly in the interlamellar environment than A1.

The title compound is prepared by solid state reaction of pressed pellets of Li2CO3, Nd2O3, and Fe(C2O4) covered with a powder of the same composition to avoid Li loss (700 °C, 12 h and 950 °C, 12—24 h).

The title compounds are characterized by powder neutron and X-ray diffraction, magnetic susceptibility and dielectric measurements, and 57Fe Moessbauer spectroscopy.

Aluminosilicate, refractory ceramic fibres devitrify to form cristobalite and mullite in high-temperature applications. The identity of phases and their development with temperature and time has been determined using x-ray powder diffractometry, and the internal standard method with fluorite reference and mullite, β-cristobalite and amorphous standards, has provided phase quantification. The formation of mullite and cristobalite as a function of exposure temperatures and times are mapped, and the presence of β−, α− and disordered cristobalite and of tridymite and α-quartz are confirmed in samples measured at room temperature. The authors are confident that well-developed cristobalite and mullite phases can be quantified and fibres devitrified at 1400°C for greater than 50 h exposure contained (51±2) wt-% mullite and (36±2) wt-% β-cristobalite with the remainder being attributed to other silica phases and remnant glass.

This review will present examples of the varied way in which Mossbauer spectroscopy has been used, with complementary analytical techniques, to gain information about metals and alloys, with cases chosen to illustrate how this information can be valuable to industry.The Mossbauer investigations reviewed have been divided into three categories:1) Monitoring the effect of deliberate modification of the metal by processing, either at the pre‐treatment stage, e.g. metal ion etching of steel surfaces prior to coating or during the modification of structure and properties, such as the formation of Al‐Fe surface alloys formed by ion implantation of Fe in Al.2) Monitoring changes in the metal not caused deliberately, i.e. the side‐effects of processing. Examples reviewed include Mossbauer studies of reactor steels, and phase transformation during intensive plastic deformation. Also the Mossbauer Effect has helped to determine the cause of staining occurring on electrogalvanized steel.3) Obtaining information to e...

Waste filter cakes from two metal finishing operations were heat treated and vitrified. Substantial weight loss during heating was due to emission of water, volatile sulphur-rich and chlorine-rich compounds, and the combustion of carbonaceous components. Estimations of CO(x), SO(x) and HCl emissions were based on chemical analyses. Upon cooling from molten, one sample remained amorphous but all others partially crystallised. Crystalline nature was dependent upon waste composition and the level of P(2)O(5) addition. Thermal stabilities of the waste forms were good, but less so than MW, a borosilicate glass developed for its high temperature stability. Mossbauer and FTIR analyses showed that iron environments in the different vitrified waste forms were very similar. Iron was present predominantly as Fe(3+), although the exact redox ratio varied slightly between waste forms. Iron in both redox states occupied distorted octahedral coordination polyhedra with similar levels of site distortion. Phosphate networks in the vitreous materials were highly de-polymerised, consisting largely of (PO(4))(3-) monomer and (P(2)O(7))(2-) dimer units. This explained the high chemical durability of these waste forms and their structural insensitivity to compositional change, underlining their suitability as hosts for the immobilisation of toxic and nuclear wastes.

The reaction of 4-ferrocenyl-1,3-dithiole-2-thione with diiodine affords an unprecedented "double" charge-transfer complex; the highly ordered ferrocenium units are held by a supramolecular polyiodide chain, and the material shows evidence of the formation of zigzag magnetic chains below 2 K.