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Zirconate pyrochlores have been extensively studied as candidate waste forms for the immobilization of actinide wastes due to their flexible crystal chemistry, excellent structural stability, and exceptional radiation tolerance. Herein, we report the synthesis of a series of compounds Eu2Zr2–xO7–2x (x = 0–1, step = 0.125) using a co‐precipitation route to form solid solutions between the two end members, Eu2Zr2O7 pyrochlore and Eu2ZrO5 defect fluorite. It is important to understand the pyrochlore to defect fluorite transformation as a function of Zr/Ln molar ratio. The structural investigation by x‐ray diffraction has shown the increasing cation disorder and corresponding structural transitions from the ordered pyrochlore to disordered pyrochlore, then to defect fluorite. While diffuse reflectance spectroscopy provides similar optical absorption features reflecting the presence of Eu(III) ion, Raman spectroscopy has revealed more details on the phase transition and short‐range structures. This work highlights the structural flexibility in zirconate materials as potential nuclear waste forms for the immobilization of actinide‐rich waste streams, especially suitable for the separated minor actinides. [ABSTRACT FROM AUTHOR]

Metal oxides possessing a large surface area, pore volume and desirable pore size provide more varieties and active industrial potentials. Nevertheless, it is very challenging to produce crystal metal oxides while keeping satisfactory porosity features, especially for ternary compositions. High temperature is usually needed to produce crystal metal oxides, which readily leads to the collapse of the pore structure. Herein, by employing a 'soft' dispersant agent and a hard silica template, ZrO2, TiO2 and Zr-Ti solid solutions having a tetragonal crystal structure are produced and the silica-leached materials are characterized from macroscopic to atomistic scales. The micron-sized particulate powders are composed of nanoscale 'building blocks', with crystallite sizes between ~8 and 21 nm. These polycrystalline ceramic powders exhibit a high specific surface area (up to ~200 m2·g−1) and pore volume (up to 0.5 cm3·g−1), with a pore size range of ~5–20 nm. Importantly, the Zr/Ti–O–Si–OH chemical bonds exist on the particle surface, with about two-thirds of the surface covered by silica. The hydroxyl groups can further post-graft organic ligands or directly associate with species. Synthesized mesoporous metal oxides are highly homogenous and could potentially be used in various applications because of their tetragonal structure and porosity features. [ABSTRACT FROM AUTHOR]

Although uranium oxide hydrate (UOH) minerals and synthetic phases have been extensively studied, the role of ammonium ions in the formation of UOH materials is not well understood. In this work, the stabilization of a synthetic UOH phase with ammonium ions and the inclusion of ammonium nitrate were investigated using a range of structural and spectroscopic techniques. Compound (NH4)2(NO3)[(UO2)3O2(OH)3] (U-N1) crystallises in the orthorhombic Pmn21 space group, having a layered structure with typical α-U3O8 type layers and interlayer (NH4)+ cations as well as (NO3)− anions. The presence of uranyl, (NH4)+ cations and (NO3)− anions were further confirmed with a combination of FTIR and Raman spectroscopies through characteristic vibrational modes. The roles of the (NH4)+ cations for charge compensation and facilitating the inclusion of (NO3)− anions via hydrogen bonding were revealed and discussed. The findings have implications for uranium geochemistry, reprocessing of spent nuclear fuel and possible spent nuclear fuel alteration pathways under geological disposal. [ABSTRACT FROM AUTHOR]

The inclusion of 1,8-octanediphosphonic acid (OA) in cucurbit[7]uril (Q[7]) has been investigated via a combined solid state and solution study. The reaction of OA and Q[7] in water led to the formation of a 1:1 inclusion compound 1 as a white crystalline material. Synchrotron single crystal X-ray diffraction revealed its detailed structure validated by Raman spectroscopy with featured vibrational modes from both organic molecules. Subsequent 1H solution NMR data supported the formation of a 1:1 inclusion complex in aqueous solution. The changes in NMR chemical shifts are consistent with the solid-state orientation in which the phosphonic acid groups of OA are oriented externally to the carbonyl portals and the intervening alkyl chain lies within the cavity of Q[7]. However, the solution study also inferred possible formations of other complexes in solution. This work highlighted the advantage of combining solid state and solution studies to reveal the detailed molecular interactions involving complex inclusion phenomena. [ABSTRACT FROM AUTHOR]

Although barium(II) ions play an important role in the natural weathering of the mineral uraninite (UO2+x) and are expected to therefore do the same for spent nuclear fuel in geological disposal, the detailed structural understanding of this role is rather limited. In this work, we report the synthesis and characterisation of two new uranium oxide hydrate (UOH) phases with barium(II) ions, a layer-structured UOH-Ba1 constructed with undulating uranyl oxide hydroxide layers incorporating hydrated interlayer barium(II) ions; and UOH-Ba2 forming a complex three-dimensional structure by linking six different types of uranium polyhedrons with barium(II) ions located in the narrow channels. Both crystal structures were revealed using synchrotron single crystal X-ray diffraction and confirmed with powder X-ray or electron diffractions. While vibrational modes were elucidated by Raman, electronic structures and the presence of pentavalent uranium were investigated using diffuse reflectance spectroscopy. This work has provided insights into the complexity of uranium crystal chemistry in the presence of barium(II) ions and has implications to both uranium geochemistry in terms of the natural weathering of uraninite and the disposal of spent nuclear fuel in the underground repository. [ABSTRACT FROM AUTHOR]

Cerium titanates possessing brannerite structure are produced by employing soft and hard templates via sol–gel processing. Powders synthesized with various hard template sizes and template to brannerite weight ratios are composed of nanoscale 'building blocks' with size ∼20–30 nm and characterized on macro-, nano- and atomic scales. These polycrystalline oxide powders exhibit specific surface area up to ∼100 m2 g−1, pore volume ∼0.4 cm3 g−1, and uranyl adsorption capacity ∼0.221 mmol (53 mg) U per gram powder. Remarkably, the materials possess significant proportion of mesopores with 5–50 nm pores representing 84–98% of total pore volume, which facilitate fast accessibility of the adsorbate to the internal surfaces of the adsorbent with adsorbed uranyl reaching over 70% of the full capacity within 15 min of contact. These mesoporous cerium titanate brannerites synthesized by the soft chemistry route are highly homogenous, stable at least in 2 mol L−1 acidic or basic solution, and may attract attention for other applications like catalysis at high temperature. [ABSTRACT FROM AUTHOR]

Y2Ti2−xSnxO7 (x = 0–2) pyrochlore sodium aluminoborosilicate glass–ceramics (GCs) are produced by calcining the pelletized Y–Ti–Sn oxide mixture and glass precursor at 1200 or 1300°C for 4 h. The metal oxide mixture is prepared by a soft chemistry route. X‐ray diffraction, Raman spectroscopy, and electron microscopy are employed to investigate the formation of pyrochlore GCs and local crystal structures. Near phase pure Ti‐rich pyrochlores are produced with minor phase SnO2 observed for Sn‐rich materials. The cell parameters of the pyrochlore structures refined by Le Bail fitting are in good agreement with the published data and increase linearly with the gradual increment of Sn substitution. With progressively increasing Sn proportion on pyrochlore B‐site, Raman characteristic bands of the pyrochlore structure become sharper and well defined. The Raman A1g peak position and its full width at half‐maximum are linearly progressed with increasing x (Sn). The presence of the melting glass facilitates the pyrochlore formation, with ceramic grain sizes ranging from submicron to microns. Transmission electron microscopy and selected area electron diffraction observations indicate the sample possesses a relatively high crystallographic perfection at the atomic level. This new series of pyrochlore GCs and the method disclosed herein may pave the way for further materials development as potential nuclear waste forms. [ABSTRACT FROM AUTHOR]

We report a flux crystal growth of Ba2[(UO2)2Ti2O8] and subsequent structural and spectroscopic studies using multiple techniques. The layered crystal structure, built up with sheets of edge‐sharing dimeric uranyl pentagonal bipyramids and dimeric TiO5 square pyramids with interlayer Ba(II) ions, was revealed by synchrotron single crystal x‐ray diffraction and confirmed with electron diffraction using a transmission electron microscope. The presence of only hexavalent uranium was confirmed by both diffuse reflectance and x‐ray absorption near‐edge structure spectroscopies, consistent with the bond valence sum calculations. Its vibrational modes were revealed by Raman spectroscopy. In addition, its implications as a potential hexavalent uranium waste form for the immobilization of uranium‐rich radioactive wastes were discussed. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of yttrium (Y3+) and lanthanide (Ln = La3+ and Gd3+) complexes with cucurbit[10]uril (Q[10]) via a self-assembly approach in a 6 M HCl solution. Crystals transforming from the initially formed two-dimensional (2D) supramolecular frameworks to 1D coordination nanotubes were observed. The coordination of Y3+ ions with Q[10] first led to the formation of a compound, {Y4(H2O)24(Q[10])3}·12Cl·4H2O (Q[10]-Y1), with a 2D supramolecular structure built up with an octanuclear complex and metal-free Q[10] via extensive second-shell interactions. Through crystals transforming, Q[10]-Y1 gradually transformed to another compound, {Y6(H2O)20(Q[10])}·18Cl·9H2O (Q[10]-Y2), with a 1D nanotube structure. Similar crystals transforming from supramolecular frameworks to 1D coordination nanotubes (Q[10]-La and Q[10]-Gd) were also observed in La3+ and Gd3+ complexes with Q[10], suggesting the unique phenomenon is a common feature in the self-assembly of Q[10] complexes with lanthanide ions. The crystal structures of these compounds were revealed by synchrotron single crystal X-ray diffraction and compared to the existing lanthanide and actinide complexes with Q[10]. [ABSTRACT FROM AUTHOR]

Cucurbit[10]uril {Q[10]} has the largest portal size and cavity in the series of Q[n] (n = 5–10) molecules. In contrast to its rich host–guest chemistry, its coordination chemistry is underdeveloped with only limited metal ions being investigated so far. In this work, we initiated the study of Q[10] complexes with Th(IV) and U(VI) ions in HCl solutions via a self-assembly approach. The coordination of Th(IV) ions with Q[10] led to the formation of a compound, {Th4(Cl)16(H2O)20(Q[10])}·nH2O (Q[10]-Th), with a unique nano-tubular structure, while U(VI) ions facilitated the formation of a compound, [(UO2)2(Cl)4(H2O)6]·(Q[10])2·HCl·nH2O (Q[10]-U), with a Q[10]-based supramolecular framework structure via intermolecular outer-surface and second-shell interactions. The structural and spectroscopic aspects of the two compounds together with their optical and thermal properties have been investigated. The successful preparation and characterization of the first two Q[10] compounds with Th(IV)/U(VI) ions highlighted the potential for further exploration of Q[10] coordination chemistry with actinide ions. [ABSTRACT FROM AUTHOR]

Environmental context: Zinc, an essential micronutrient often applied to crops as a fertiliser, can be difficult to analyse in plants due to limitations of conventional techniques. Here, we use radiotracers and a non-destructive imaging technique to visualise how zinc applied as a nanofertiliser moves within wheat plants over time. This is an important step towards developing cost-effective fertilisers to help solve one of the world's most widespread plant deficiencies. Zinc (Zn) deficiency affects half of the world's arable soil and one-third of the world's human population. Application of Zn foliar fertilisers to cereal crops can be an effective way to increase grain Zn content; however, commonly used formulations can scorch the leaf (e.g. soluble Zn salts) or are prohibitively expensive (e.g. chelated Zn, ZnEDTA). Zinc oxide nanoparticles (ZnO-NPs) may offer an efficient and cost-effective alternative, but little is known regarding the mechanisms of Zn uptake and translocation within the plant. Foliar-applied Zn is analytically challenging to detect, locate and quantify, as it is omnipresent. Furthermore, any single analytical technique does not have the detection limit or spatial resolution required. In this study, the uptake and mobility of foliar-applied ZnEDTA, ZnO-NPs and ZnO microparticles (ZnO-MPs) to wheat (Triticum aestivum L.) were investigated using inductively coupled plasma mass spectroscopy (ICP-MS), synchrotron-based X-ray fluorescence microscopy (XFM) and radiotracing techniques using 65Zn-labelled formulations. The three techniques were compared to highlight limitations and advantages of each. We also report, for the first time, a novel time-resolved in vivo autoradiography imaging technique that can be used to visualise 65Zn in live plants treated with foliar applications of 65ZnO-NPs and MPs. The images were supplemented by gamma spectroscopy analysis for quantification. The results of this study provide important insights into the analytical challenges faced when investigating foliar-applied Zn nanofertilisers in plants. Potential solutions using nuclear techniques are also discussed, which in turn may ultimately lead to the development of more efficient foliar fertilisers. Environmental context. Zinc, an essential micronutrient often applied to crops as a fertiliser, can be difficult to analyse in plants due to limitations of conventional techniques. Here, we use radiotracers and a non-destructive imaging technique to visualise how zinc applied as a nanofertiliser moves within wheat plants over time. This is an important step towards developing cost-effective fertilisers to help solve one of the world's most widespread plant deficiencies. [ABSTRACT FROM AUTHOR]

The formation of CaZrTi2O7 zirconolite and its crystallization in sodium alumino‐borosilicate glass has been investigated via sintering in air. The ceramic precursor is prepared using a soft chemistry route to ensure ultimate mixing of the reactants at the molecular level. A nearly phase pure CaZrTi2O7 zirconolite is formed after sintering the ceramic precursor at 1400°C for 12 hours. In order to form zirconolite glass‐ceramics, various processing conditions are investigated including sintering temperatures, different glass composition precursors, and ceramic to glass weight ratios. Zirconolite crystallization on the surface and inside of glass‐ceramic‐pelletized samples is investigated. Higher ceramic to glass weight ratio leads to the formation of zirconolite as crystalline phase, which is quite dominant in glass. [ABSTRACT FROM AUTHOR]

Abstract: Brannerite‐based glass‐ceramics with relatively high actinide waste loadings are potential waste forms for the immobilization of actinide‐rich radioactive wastes containing process chemicals. In this work, the crystallization of pentavalent uranium brannerite phases in glass with the incorporation of yttrium/cerium/europium has been investigated. The formation of brannerite phases in glass has been confirmed with X‐ray diffraction and Raman spectroscopy. The evolution of microstructures and the development of micro pores in brannerite phases have been revealed by scanning electron microscopy with the nominal formula, Y0.51U0.49Ti2O6, Ce0.65U0.35Ti2O6, and Eu0.53U0.47Ti2O6, being determined with energy‐dispersive spectroscopy. The presence of dominant U5+ species has been proven with both diffuse reflectance spectroscopy and X‐ray absorption near‐edge spectroscopy. In addition, the systematic Raman band shifts with the mean cation radius in the studied brannerite series have been observed and discussed. [ABSTRACT FROM AUTHOR]

New microsphere sorbents are reported, which could find application in demanding radiation environments and especially as targets for the production of nuclear medicines by neutron irradiation. An easily-synthesized Zr anionic complex was introduced into quaternary amine-functionalised polystyrene-divinylbenzene-based anion-exchange resins by batch adsorption. Upon carbothermal reduction, the precursors were converted to porous carbon matrices containing particles of ZrC and ZrO2 polymorphs. The most phase-pure material, ZrAX-1, possessed high surface area, multi-scale porosity and high mechanical strength. Adsorption of Re and W was investigated and its possible deployment as a reusable host for the production of 188W/188Re is discussed. [ABSTRACT FROM AUTHOR]

Four uranyl oxide hydrate phases with heavy lanthanide ions, [Ln(UO2)2O3(OH)]·0.5H2O [Ln = Tb (1), Dy (2), Ho (3) and Yb (4)], have been synthesized under hydrothermal conditions at 240 °C and characterized. SEM-EDS revealed that these phases have very similar thin plate morphologies with a U to Ln atomic ratio of 2 : 1, which is further confirmed by TEM-EDS. Their high magnification TEM bright field images showed small crystalline domains (∼2–5 nm) with preferred crystal orientations. Both XRD and TEM SAED confirmed that they crystallize in the trigonal crystal system with the P3̅m1 space group. Raman characterization revealed the typical vibration modes for the uranyl units with the calculated U=O bond lengths are comparable to the values reported for other UOH phases with d-transition metal ions as the interlayer species. The possible presence of a pentavalent uranyl unit has been ruled out by UV-vis-NIR spectroscopy. The thermal and optical properties have also been investigated and reported. [ABSTRACT FROM AUTHOR]

Ln2Ti2O7 (Ln=Y and Gd) pyrochlore glass-ceramics have been fabricated successfully via internal crystallization. Subsequently, the phase evolution from Ln2Ti2O7 pyrochlores to Ln0.5U0.5Ti2O6 brannerites in glass with uranium (U) substitutions on the Ln-site of Ln2Ti2O7 has been investigated using X-ray diffraction, scanning electron microscope-electron dispersive spectroscopy, transmission electron microscopy, Raman and diffuse reflectance spectroscopy. Combined characterization by XRD, SEM- EDS and TEM SAED confirms the structures and phase evolution while Raman spectroscopy reveals characteristic vibration modes for both pyrochlore and brannerite. In addition, DRS of the U5+ ion has been used to probe the phase evolution, with the corresponding f- f transition band of 2 F7/2 energy level significantly shifting to longer wavenumbers due to the local coordination environment changing from eightfold coordination in pyrochlore to sixfold coordination in brannerite. [ABSTRACT FROM AUTHOR]

Brannerite-based glass-ceramics have been developed as potential waste forms for the immobilization of actinide-rich radioactive wastes. For the first time, the formation of brannerite phases in glass has been demonstrated using uranium (U) and plutonium (Pu) with additions of gadolinium and hafnium as neutron absorbers. Both XRD and SEM- EDS confirm that brannerite is the dominating phase with compositions close to Y0.5U0.5Ti2O6, Gd0.2Pu0.3U0.5Ti2O6, and Gd0.1Hf0.1Pu0.2U0.6Ti2O6 internally crystallized in the glass. TEM SAED and Raman spectroscopy reveal the typical structure and vibration modes for brannerite. In addition, the presence of U5+ species as designed in the formulations has been confirmed by diffuse reflectance spectroscopy. More importantly, the U and Pu were partitioned exclusively in the ceramic phases with no detectable actinide in the glass. [ABSTRACT FROM AUTHOR]

Two new holmium (Ho) oxalato complexes have been synthesized under hydrothermal conditions and structurally characterized. [Ho(OH)2]2(C2O4) (1) has a 3-D structure with Ho-(μ3-OH) hydroxide layers connected by μ4-bridging oxalate ligands forming a unique hybrid structure. Sr(H2O)4[Ho(C2O4)2(H2O)]2·2H2O (2) has a 3-D structure built through μ2-bridging oxalate ligands connecting hexagonal Ho oxalate layers with hydrated Sr2+ ions in the channels. Different oxalate ligand arrangements around the metal ions control the structural alterations among the lanthanoid double oxalates even with similar formulas. Both structures have been discussed and compared to the existing lanthanoid oxalato complexes. In addition, their vibration modes, thermal stabilities, electronic structures, and magnetic properties have been further investigated and reported. Both 1 and 2 show the deviation of the magnetic behaviors from the Curie–Weiss law due to the crystal field effects. [ABSTRACT FROM AUTHOR]

Two new iso-structured uranyl oxide hydroxyl hydrate (UOH) phases with the incorporation of cobalt(ii) or nickel(ii) ions have been synthesised under hydrothermal conditions and structurally characterised. Both K4Co(OH)3(H2O)9[(UO2)12(O)7(OH)13] (1) and K4Ni(OH)3(H2O)9[(UO2)12(O)7(OH)13] (2) have two-dimensional (2D) polymeric uranyl oxohydroxyl layers with either potassium and hydroxyl cobalt(ii) (1) or potassium and hydroxyl nickel(ii) (2) ions between layers via uranyl–cation interactions. This work highlights the feasibility of making new UOH phases via a hydrothermal route at relatively higher solution pHs. It also demonstrates that other transition metal ions which are readily available in the environment may also be incorporated into such UOH phases during the natural weathering of uraninite as well as during the storage and disposal of spent nuclear fuels. [ABSTRACT FROM AUTHOR]

Contrary to the fairly well established structural chemistry of uranium(VI) with aromatic polycarboxylate ligands, the knowledge on thorium(Th) structural chemistry with this family of ligands is very limited. In this paper, we report the synthesis, spectroscopic and thermal studies, and crystal structures of three Th organic frameworks with 1,2,4,5-benzenetetracarboxylate (btca) or 1,4-benzenedicarboxylate (bdc). Both [Th(btca)(DMF)(HO)] ( 1) and [Th(bdc)(DMF)] ( 2) (DMF = dimethylformamide) have two dimensional (2D) layered structures constructed with 9- ( 1) or 10- ( 2) fold coordinated Th polyhedrons and µ-btca ( 1) or µ-bdc ( 2) ligands, respectively, with two coordinated DMF molecules in cis- ( 1) or trans- ( 2) positions on each Th atom. The third phase, [Th(bdc)] ( 3), has a 3D pillared framework built with eightfold coordinated Th polyhedrons and µ-bdc ligands. Their vibrational modes have been investigated and correlated to the structures. VT-PXRD confirmed that 3 is thermally robust to 500 °C and the weight loss at ~300 °C is due to the loss of water molecules in the solvent accessible voids in the crystal lattice. Graphical Abstract: Thorium(IV) organic frameworks (TOC): Three new thorium organic frameworks with aromatic polycarboxylate ligands have been synthesized and characterized. 2D layered structures are favored at room temperature and a thermal robust, 3D thorium organic framework has been made under hydrothermal conditions. Their vibrational modes and thermal stabilities have been further investigated. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Two new double thorium oxalates with sodium ions have been prepared and characterized by using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), Raman spectroscopy and single-crystal X-ray diffraction. The crystal structure of Na4[Th(C2O4)4] ·5.5H2O ( 1) contains infinite chains, [Th(μ2-C2O4)2(C2O4)3] n4 n-, with three terminating bidentate and two bridging tetradentate oxalate ligands. The crystal structure of Na10[Th2(C2O4)9] ·15H2O ( 2) comprises unique dimers, [Th2(μ2-C2O4)(C2O4)8]10-, with Th atoms being coordinated by five oxalato ligands, four terminating bidentate and one bridging tetradentate. The structure is the first dimer of tetravalent actinide oxalato complexes. The spectroscopic results are in good agreement with the crystal structures. [ABSTRACT FROM AUTHOR]

Fibre drawing is used to fabricate indefinite media based on wire array metamaterials. Fibres containing arrays of indium wires embedded in polymer are drawn using an optical fibre draw tower, a technique that is intrinsically scalable to larger‐volume fabrication. During drawing, the surface tension of the liquid indium can result in fluctuations to the wire diameter through the Plateau–Rayleigh instability. This is investigated and minimised through a modification of the draw process to achieve wire diameters as low as 1 micrometer. Such wire array fibres are assembled and characterised as electric metamaterials through the resulting high‐pass filtering behaviour. By controlling the draw ratio, the fibre drawing technique is shown to produce electric metamaterials over a wide range of frequencies, from the THz through to the edge of the mid‐IR. [ABSTRACT FROM AUTHOR]

Pyrochlore-structured lanthanide stannate ceramic ( Ln2 Sn2 O7) has been synthesized via a new complex precipitation method. A suite of characterization techniques, including FTIR, Raman, X-ray, and electron diffraction as well as nitrogen sorption were employed to investigate the structural evolution of the synthesized and calcined powder. Raman, XRD, and selected area electron diffraction results confirm the presence of the pyrochlore structure after calcination of the powder above 1200°C. TEM imaging shows fine crystallites gradually increased in size from approximately 100 nm to about 500 nm with higher calcination temperatures. Grain growth and powder densification upon increasing the calcination temperature was confirmed by nitrogen sorption results. This aqueous synthetic method provides a simple pathway for the preparation of homogeneous lanthanide stannate ceramics. [ABSTRACT FROM AUTHOR]

Lanthanum zirconate has been prepared via a new chemical synthesis method by combining sol-gel processing and complex precipitation. The synthesis was carried out in aqueous solution under ambient conditions. The synthesized powder possessed the pyrochlore superstructure upon calcination above 1200°C. A suite of characterization techniques, including FTIR, Raman, X-ray and electron diffraction, TEM, SEM, and nitrogen sorption were employed to investigate the microstructural evolution and bulk properties. Dense ceramics (>90% relative density) were obtained after sintering at 1400°C, without need for additional processing (i.e., hot or cold isostatic pressing) or any milling steps. A mechanism has been proposed that elucidates molecular assembly of this chemical synthesis method. [ABSTRACT FROM AUTHOR]

A binder-free titania paste was prepared by chemical modification of an acidic TiO2 sol with ammonia. By varying the ammonia concentration, the viscosity of the acidic TiO2 suspension increased, thereby allowing uniform films to be cast. The photoelectrochemical performance of TiO2 electrodes, cast as single layers, was dependent on the thermal treatment cycle. Fourier transform infrared spectroscopy was used to characterize the extent of residual organics and found that acetates from the TiO2precursor preparation were retained within the electrode structure after thermal treatment at 150 °C. Electrodes of nominal thickness 4 μm produced an energy conversion efficiency as high as 5.4% using this simple thermal treatment. [ABSTRACT FROM AUTHOR]

Rutile powder was synthesized via sol-gel processing of Tyzor TE precursor in an aqueous solution at 40°C-50°C. A suite of characterization techniques, including FTIR, Raman, X-ray, and electron diffraction, were employed to investigate the microstructural evolution. The synthesized powder was phase-pure rutile possessing high surface area (144.7 m2/g), an average pore size of 24.9 nm, and pore volume of 0.66 cm3/g. A reaction mechanism is proposed for the preferential evolution of rutile over other titania polymorphs (i.e. amorphous or anatase). [ABSTRACT FROM AUTHOR]

Titanium ethoxide [Ti(OEt)4] was modified with aminobenzoic acid (AB) or aminosalicylic acid (AS) in order to control the hydrolysis and condensation rates, and to allow the preparation of organic–inorganic hybrid materials. A suite of complementary techniques, including Fourier transform infrared spectroscopy, NMR, SEM, thermogravimetric analysis, and X-ray diffraction, were used to elucidate the effects of incorporating an organic functional group into the precursor chemistry and its subsequent affect on the structure and morphology of the resultant hybrid material. The annealing behavior of the resulting hybrid titanium base materials was also investigated. Our studies show that both amino acid organic ligands, AB and AS, chemically bounded to the titanium complex, effect the precursor reactivity, specifically the hydrolysis and polycondensation reactions, which control the evolution and formation of the nanohybrid-based titania material. Following sol–gel processing, the nanohybrid materials are amorphous, due to the incorporation of the organic component. The phase transition (amorphous–anatase–rutile) observed during annealing from 25° to 800°C show subtle differences in the crystallization behavior, which are associated with the nature of the organic ligand. [ABSTRACT FROM AUTHOR]

The modification of titanium alkoxides by chemical reactions with ligands yields complexes or molecular clusters that are substantially different from those of the parent alkoxides. In this study, we investigate the structural evolution of powders and thin films prepared from two titanium oxo-alkoxyacylate clusters with different oxo-core structures [Ti6(μ3-O)2(μ2-O)2](CH3COO)8(μ2-OiPr)2(OiPr)6 and [Ti6(μ3-O)6](μ-RCOO)6(OiPr)6 ([6,4] and [6,6], respectively) as a function of annealing temperature. The structural evolution of powders and thin films prepared from the corresponding parent alkoxide Ti(OiPr)4 (TiP) were also investigated for comparison. In all powders, the amorphous-to-anatase transformation occurred upon heating to 400°C. In sharp contrast, the anatase-to-rutile transformation of the powder prepared from the [6,6] cluster was significantly inhibited compared with the conventionally derived powder, with no rutile being detected even after annealing at 800°C for 1 h. This was attributed to the small crystallite size in the [6,6]-derived powder, which is lower than the critical size previously reported for the anatase-to-rutile transformation in similar sol–gel-derived materials. In thin films, the amorphous-to-anatase phase transition also occurred at temperatures as low as 400°C for coatings deposited from conventional TiP precursor and [6,4] cluster solutions. However, in contrast to the corresponding powders no rutile nucleation occurred even at 800°C in either film. [ABSTRACT FROM AUTHOR]

Chemical vapour deposited diamond was irradiated with 5 MeV carbon ions to simulate the damage caused by collision cascades from neutron irradiation in a fusion environment. Ion-irradiated samples were then exposed to a deuterium plasma in MAGPIE with ion flux of ∼1.3 × 1021 ions m−2 s−1. Raman and near edge x-ray absorption fine structure (NEXAFS) spectroscopy were used to characterize the degree of disorder and sp2-bonding induced by the ion irradiation. The signals of sp2-bonded and disordered carbon were observed to decrease after exposure to the deuterium plasma, although sharp Raman peaks indicative of vacancy and interstitial defects induced by the MeV ions were less affected. Recovery of a diamond-like surface after plasma exposure was evident in the NEXAFS spectra. Elastic recoil detection analysis showed that the ion-damaged diamond retained more deuterium than diamond exposed only to deuterium plasma. For the case of unirradiated samples, diamond retained more deuterium than graphite. However, for the case of the ion-irradiated samples, diamond exhibited less deuterium retention than graphite. [ABSTRACT FROM AUTHOR]

A correction to the article "A study of TiO2 binder-free paste prepared for low temperature dye sensitized solar cells," by Jeremy H. Yune and colleagues that was published in the 2013 issue, is presented,