Zhaoming Zhang

Australian Nuclear Science and Technology Organisation | ANSTO · Nuclear Fuel Cycle

Technetium is unique amongst the transition metals in that no stable isotopeexists. Technetium-99 is a major fission product of uranium-235 (approx. 7% ofyield), is found in radioactive waste from nuclear fuel and can occur due to theproduction of plutonium. Due to its long half-life (t = 2.1 × 10 y) and highmobility through geological formations,...

A combined experimental and theoretical investigation is presented which examines the compressibility of two SrUO4-x polymorphs, α and β, under hydrostatic conditions and explains the contrasting chemical and mechanical behaviours of these in terms of differences in oxygen defect formation chemistry. Via Rietveld refinements against in situ neutron...

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 dif...

Optical quality cm-sized LiInSe2 crystals were grown using the Bridgman–Stockbarger method, starting from pure element reagents, under the conditions of a low temperature gradient of 5–6 degrees/cm and a slight melt overheating. The phase purity of the grown crystal was verified by the powder XRD analysis. The thermophysical characteristics of LiIn...

A carbon-fibre reinforced carbon-matrix (C/C) composite was irradiated with 30 MeV C⁶⁺ ions to a peak damage of ∼25 dpa. Ion irradiation-induced microstructural changes were mainly studied using Raman spectroscopy. The irradiation-induced crystal lattice defect accumulation in the C/C composite was compared with a reference of PCIB graphite (nuclea...

The previously unattained fabrication of single phase Ln2ZrO5 (Ln = Sm, Eu, Gd, and Tb) compounds via relatively low sintering temperature (1400°C) is achieved in this study using a coprecipitation method. The crystal structures have been investigated by neutron, synchrotron X‐ray powder diffraction, and electron diffraction techniques. While the g...

The structure of lead-technetium pyrochlore has been refined in space group F d 3 ¯ m with a = 10.36584(2) Å using a combination of synchrotron X-ray and neutron powder diffraction data and confirmed via Electron Diffraction. The oxide is found to be oxygen deficient with a stoichiometry of Pb2Tc2O7-d. Displacive disorder of the Pb cations is evide...

The long-range (average) and short-range (local) structures in the Yb2(Ti2-xYbx)O7-x/2 (x = 0.00–0.67) series were studied using a combination of diffraction and spectroscopic techniques. The average structure, established from synchrotron X-ray and neutron powder diffraction data, shows the development of multiphase regions from x = 0.134 and the...

The phase formation, structures, microstructures, uranium valences and magnetic properties of LnUO4 (Ln = Dy and Ho) were investigated. Although sintering of the precursors in argon at 1450 °C for seven days and 1400 °C for six hours both resulted in the desired phase, sintering at higher temperature for longer duration led to the formations of wel...

The long-range average and short-range local structures in the Tm2(Ti2-xTm x )O7-x/2 (x = 0.00-0.67) series were studied using a combination of diffraction and spectroscopic techniques. The long-range average structure, established from synchrotron X-ray and neutron powder diffraction data, shows the development of multiphase regions from x = 0.134...

Atomic-scale disorder plays an important role in the chemical and physical properties of oxide materials. The structural flexibility of pyrochlore-type oxides allows for crystal-chemical engineering of these properties. Compositional modification can push pyrochlore oxides toward a disordered defect-fluorite structure with anion Frenkel pair defect...

A systematic investigation examining the origins of structural distortions in rutile-related ternary uranium AUO4 oxides using a combination of high-resolution structural and spectroscopic measurements supported by ab initio calculations is presented. The structures of β-CdUO4, MnUO4, CoUO4, and MgUO4 are determined at high precision by using a com...

Molten-salt-based energy generation and energy-storage systems are expected to function under plasticity-imparting in-service operating conditions. It is thus of utmost importance to understand the effect of these operating conditions on the corrosion performance of molten-salt-facing structural alloys. Here, we investigate the impact of high-tempe...

A uranium oxide hydrate framework, [U(H2O)2]{[(UO2)10O10(OH)2][(UO4)(H2O)2]} (UOF1), was synthesized hydrothermally using schoepite as a uranium precursor. The crystal strucutre of UOF1 was revealed with synchrotron single-crystal X-ray diffraction and confirmed with transmission electron miscroscopy. The typical uranyl oxide hydroxide layers simil...

Molten-salt-based energy generation and energy-storage systems are expected to function under plasticity-imparting in-service operating conditions. It is thus of utmost importance to understand the effect of these operating conditions on the corrosion performance of molten-salt-facing structural alloys. Here, we investigate the impact of high-tempe...

A pyrochlore‐rich multiphase ceramic waste form was prepared by the alkoxide‐route and consolidated by sintering in air. Cerium (Ce) was used as a surrogate for plutonium (Pu), which was found in both the major pyrochlore and minor perovskite phases, but not the minor rutile phase. A synchrotron‐based fluorescence X‐ray absorption near‐edge spectro...

The surfaces of Sb2Te3 topological insulator crystals were implanted using a 40 keV chromium ion beam. To facilitate uniform doping, the Sb2Te3 was passivated with a thin TiO2 film before the implantation step. The resulting chemical structure was studied using atomic-resolution transmission electron microscopy. A fluence of 7 × 10¹⁵ ions/cm² at 40...

The double perovskite Ba2CoOsO6, synthesized using solid-state methods at ambient pressure, is shown as a rare example of an oxide adopting the 6L-trigonal (S.G.: P3̅m1) perovskite structure. The structure, refined using a combination of X-ray and neutron diffraction data, showed the Co and Os were ordered over the two dimer sites with additional o...

Pyrochlore glass‐ceramics (GCs) have been investigated with samples fabricated via both sintering and hot isostatic pressing (HIPing) of a mixed oxide precursor. It has been demonstrated that sintering at 1200°C in air is necessary to obtain well‐crystallized pyrochlore crystals in a sodium aluminoborosilicate glass through a one‐step controlled co...

The molten salt corrosion performance of a Ni–Mo–Cr (GH3535) alloy weldment, produced using matching filler metal, was assessed. Corrosion testing was performed in FLiNaK molten salt at 750 oC for 500 h. Present results reveal that, despite a similar chemical composition, the weld metal has somewhat superior corrosion resistance to the parent metal...

We have synthesized two uranyl oxide hydrate (UOH) phases incorporating La(III) or Nd(III) ions under hydrothermal conditions. Investigations with scanning electron microscopy and transmission electron microscopy (TEM) revealed thin-plate morphologies with a U-to-Ln atomic ratio of 2:1 (Ln = La or Nd), while single-crystal X-ray diffraction and TEM...

Uranium brannerite phases with terbium(III) or dysprosium(III) ions have been investigated. The precursors with molar ratio of 0.5:0.5:2 (Ln: U: Ti with Ln = Tb or Dy) were prepared and calcined at 750°C in argon. Sintering the pelletized samples in argon at 1200°C led to the formation of pyrochlore phases with TiO2 rutile and U‐rich oxides while s...

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 the current work, the crystallization of pentavalent uranium brannerite phases in glass with the incorporation of yttrium/cerium/europium has been investig...

In situ synchrotron powder X-ray diffraction measurements have demonstrated that SrUO4 undergoes a reversible phase transformation under reducing conditions at high temperatures, associated with the ordering of oxygen defects resulting in a lowering of crystallographic symmetry. When substoichiometric rhombohedral α-SrUO4- x, in space group R3̅ m w...

We report the systematic design, preparation and characterization of the first commensurate member of the oxide-ionic conducting, (3+3)-D modulated, Type II phases of doped δ-Bi2O3. The incommensurate Type II modulation vector ε was previously described as continuously variable, but high-resolution synchrotron X-ray powder diffraction data show tha...

We have established the stability and range of the cubic type II phase of Bi1 − xWxO1.5 + 1.5x using a combination of X-ray diffraction, neutron diffraction and X-ray absorption spectroscopy. Type II is a high temperature modification that can be obtained by quenching/rapid cooling of samples with compositions between x = 0.148 to x = 0.185. Slower...

The Ln2TiO5 (Ln = lanthanides and yttrium) compounds find use in nuclear, electronic and battery applications but there is a lack of information correlating the synthesis, structure and properties of these materials. We give an in depth review of the current available literature on the Ln2TiO5 compounds. New structural findings of the TbxYb2-xTiO5...

The structure of BaThO3, obtained by solid state synthesis, was refined for the first time by the Rietveld method using a combination of synchrotron X-ray and neutron powder diffraction data. BaThO3 has an orthorhombic structure at room temperature, in space group Pbnm with a = 6.3491(5), b = 6.3796(4) and c = 8.9907(7) Å. Heating BaThO3 to above 7...

TcO2 has a monoclinic structure in space group P21/c between 25 and 1000 °C, as established using a combination of synchrotron X-ray and neutron powder diffraction methods, and is found to remain monoclinic in the same space group. Thermal expansion of the lattice is highly anisotropic, with negative thermal expansion of the b axis observed above 7...

The crystal and magnetic structures of double perovskites of the type Ba2-xSrxYOsO6 were studied by synchrotron X-ray and neutron powder diffraction methods, bulk magnetic susceptibility measurements, and X-ray absorption spectroscopy. The structures were refined using combined neutron and synchrotron data sets based on an ordered array of corner-s...

We have studied the long-range average and short-range local structures in Y2Ti2-xHfxO7 (x = 0-2.0) using diffraction and spectroscopy techniques respectively. Both neutron and synchrotron X-ray powder diffraction data show a clear phase transition of the average structure from ordered pyrochlore to disordered defect-fluorite at x ~ 1.6; the long-r...

In situ neutron and synchrotron X-ray diffraction studies demonstrate that SrUO4 acts as an oxygen transfer agent, forming oxygen vacancies under both oxidizing and reducing conditions. Two polymorphs of SrUO4 are stable at room temperature, and the transformation between these is observed to be associated with thermally regulated diffusion of oxyg...

A combination of S-XRD and NPD demonstrate the structure of Ba2Y0.879UO6+x to be monoclinic in space group I2/m. That the U is hexavalent is evident from the U L2-edge XANES measurements. This appears to be a rare example of a double perovskite containing vacancies at the octahedral B-sites and interstitial oxygen defects, which combine to stabilis...

The structures of some AUO4 (A=Ca, Sr, or Ba) oxides have been determined using a combination of neutron and synchrotron X-ray diffraction, supported by X-ray absorption spectroscopic measurements at the U L3-edge. The smaller Ca cation favours a rhombohedral AUO4 structure with 8-coordinate UO8 moieties whilst an orthorhombic structure based on UO...

The crystal structures of seven samples of orthorhombic (Pnma) Ln2TiO5 compounds with Ln=La, Pr, Nd, Sm, Gd, Tb and Dy were refined by Rietveld analysis of synchrotron X-ray powder diffraction (S-XRD) data. With increasing size of the lanthanide cation, the lattice parameters increase systematically: c by only ~1.5% whereas both a and b by ~6% from...

From X-ray diffraction, scanning electron microscopy, X-ray absorption near edge structure (XANES) and diffuse reflectance (DR) spectroscopic studies, it was found that approximately 0.03 formula units (f.u.) of mixed hexavalent and pentavalent U, but <0.001 f.u. of Pu or Np, can be dilutely incorporated into the Ti site of rutile, TiO2, sintered a...

Using the vertical Bridgman method, the single crystal of low temperature phase SrMgF4 is obtained. The crystal is in a very good optical quality with the size of 10×7×5 mm3. Detailed photoemission spectra of the element core levels are determined by a monochromatic AlKa (1486.6 eV) X-ray source. Moreover, the first-principles calculations are perf...

A novel soft chemistry route was developed to synthesize Y2HfxTi2−xO7 (0≤x≤2.0) oxide solid solution. An aqueous solution containing reactants was produced to ensure the combustion reaction taking place at the molecular level. A suite of characterization techniques, including X-ray diffraction, Raman, transmission electron spectroscopy, as well as...

Three new coordination polymers of uranium(VI) with pyromellitic acid (H4btca) have been synthesized and structurally characterized. (ED)[(UO2)(btca)]·(DMSO)·3H2O (1) (ED=ethylenediammonium; DMSO=dimethylsulphoxide) has a lamellar structure with intercalation of ED and DMSO. (NH4)2[(UO2)6O2(OH)6(btca)]·~6H2O· (2) has a 3D framework built from 7-fol...

The relaxor ferroelectric K0.5Bi0.5TiO3 has been synthesised in a solid-solution series with K0.5Bi0.5ZrO3, as K0.5Bi0.5Ti1-xZrxO3. High-resolution synchrotron X-ray powder diffraction and X-ray absorption near edge structure spectroscopy were used to characterise the long-range average and local structural behaviour. Rietveld refinements against d...

The crystal structures of the series of ordered double perovskites Ba2-xSrxYRuO6 (0 ≤ x ≤ 2) were studied by high resolution synchrotron X-ray diffraction. The materials displayed a sequence of structures Fm3 @#x0305;m (a^0 a^0 a^0 ) (→┴(x=0.6) ) I4/m (a^0 a^0 c^-)→┴(x=1.0) I2/m (a^- a^- c^0)(→┴(x=1.4) ) P2_1/n (a^- a^- a^+ ) associated with increa...

Tc L3-edge XANES spectra have been collected on powder samples of SrTcO3 (octahedral Tc4+) and NH4TcO4 (tetrahedral Tc7+) immobilized in an epoxy resin. Features in the Tc L3-edge XANES spectra are compared with the pre-edge feature of the Tc K-edge as well as other 4d transition metal L3-edges. Evidence of crystal field splitting is obvious in the...

The structural properties of (Bi0.5Na0.5)Ti1-xZrxO3 (where 0 ≤ x ≤ 0.7) have been investigated using powder diffraction and X-ray absorption spectroscopy. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Doping small amounts of Zr into the B site of (Bi0.5Na0.5...

The title compound is synthesized in aqueous medium from a mixture of titanium(IV) bis(ammonium lactato)dihydroxide and Ce(NO3)3 (sintering between 800 and 1400 °C).

The incorporation of uranium into gadolinium zirconate (Gd2Zr2O7) is investigated by synchrotron X-ray powder diffraction and X-ray absorption near-edge structure (XANES) spectroscopy. The results suggest that the uranium cation is largely located on the pyrochlore B-site instead of the targeted A-site. Cation disorder in Gd2Zr2O7 and U-doped Gd2Zr...

Atomic scale modelling suggests that excess oxygen can be accommodated in the group II perovskite zirconates by the formation of peroxide ion defects. This is unprecedented given the lack of charge compensating defects required for standard excess oxygen accommodation. The solution energy of O2 was predicted to be close to zero for BaZrO3, accommod...

We have studied the long-range average and local structures in a number of zirconium containing materials of the type A2B2O7 ( A = Ln or Y; B = Zr, Hf or Sn) using synchrotron X-ray and neutron powder diffraction and X-ray absorption spectroscopy. Studies of the system Gd2-xTbxZr2O7 include neutron diffraction data, obtained at λ ≍ 0.497 Å to minim...

Cerium titanate CeTi2O6 was prepared by a new soft chemistry route in aqueous solution. A suite of characterization techniques, including X-ray diffraction, thermal analysis, vibrational spectroscopy, and scanning and transmission electron spectroscopy, were employed to investigate the brannerite structure formation and its bulk properties. The syn...

The key role played by bismuth in an average intermediate oxidation state in the magnetoelastic spin-gap compounds Ba3BiRu2O9 and Ba3BiIr2O9 has been confirmed by systematically replacing bismuth with La(3+) and Ce(4+). Through a combination of powder diffraction (neutron and synchrotron), X-ray absorption spectroscopy, and magnetic properties meas...

We have studied the long-range average and local structures in Y2Sn2–xZrxO7 (x = 0–2.0) using synchrotron X-ray powder diffraction and X-ray absorption spectroscopy, respectively, and by theoretical methods. While the diffraction data indicate a clear phase transition from ordered pyrochlore to disordered defect-fluorite at x 1.0–1.2, X-ray absorpt...

The pyrochlore-defect fluorite phase transition in the mixed-metal zirconate Nd2-xYxZr2O7 (0 ≤ x ≤ 2) solid solution was investigated using synchrotron X-ray and neutron diffraction, as well as X-ray absorption spectroscopy. Diffraction analysis revealed a two-phase region between 1.0 ≤ x ≤ 1.2. In the pyrochlore phase, Zr L3-edge XANES analysis de...

The pyrochlore-defect fluorite order-disorder transition has been studied for a series of oxides of the type Gd2-xTbxZr2O7 by a combination of diffraction and spectroscopy techniques. Synchrotron X-ray diffraction data suggest an abrupt transition from the coexistence of pyrochlore and defect fluorite phases to a single defect fluorite phase with i...

a b s t r a c t A series of uranium-containing gadolinium zirconate samples have been fabricated at 1450 °C in oxidiz-ing, inert and reducing atmospheres. X-ray diffraction, Raman spectroscopy and transmission electron microscopy have been utilized to confirm adoption of pyrochlore or defect fluorite structures. X-ray dif-fraction allowed determina...

Fifteen perovskite manganites Sr1-xPrxMnO3 with x = 0.1—0.6 in steps of 0.025 are prepared by solid state methods and their crystal structures are determined by synchrotron powder XRD.

Fifteen perovskite manganites Sr1-xPrxMnO3, x=0.1-0.6 in steps as fine as 0.025, have been synthesized by solid state methods and their crystal structures determined using synchrotron X-ray powder diffraction. At room temperature two first order phase transitions associated with changes in the orbital iordering and the tilting of the corner shared...

The system Y2Sn2-xZrxO7 (0.0 [less-than-or-equal] x [less-than-or-equal] 2.0) undergoes a phase transformation from ordered pyrochlore (Fd[3 with combining macron]m) to defect fluorite (Fm[3 with combining macron]m) actuated by the substitution of Zr for Sn. X-ray diffraction patterns map the retention of the pyrochlore structure up to x = 1.2. For...

a b s t r a c t Pyrochlore based glass-ceramics have been developed, from concept to reality, for the immobilization of actinide-rich nuclear wastes. Compared with zirconolite based glass-ceramics, they are less sensitive to the processing redox conditions and can double actinide waste loadings thus decreasing volumes of the consolidated waste form...

Pyrochlore based glass-ceramics have been developed, from concept to reality, for the immobilization of actinide-rich nuclear wastes. Compared with zirconolite based glass-ceramics, they are less sensitive to the processing redox conditions and can double actinide waste loadings thus decreasing volumes of the consolidated waste forms, and subsequen...

The zirconates Ln(2)Zr(2)O(7) (Ln = lanthanoid) have been studied using a combination of Zr L-edge X-ray absorption near edge structure (XANES) and synchrotron X-ray and neutron powder diffraction methods. These studies demonstrate that as the size of the lanthanoid cation decreases, the local structure evolves smoothly from the ideal pyrochlore to...

Two Ce3+ containing double perovskites Ba2CeMO6 (M = Nb and Ta) have been prepared through the use of mildly reducing conditions, and the Ce valence state has been shown to be +3 through Ce L-edge X-ray absorption measurements. Both oxides adopt a monoclinic structure in I2/m at room temperature and undergo two phase transitions upon heating, a dis...

We have studied the crystal structure of mixed-valence Sr0.7Ce0.3MnO3 from 4.2 to 973 K using high-resolution neutron powder diffraction. The crystal structure is tetragonal in space group I4/mcm at 4.2–923 K and cubic in Pm3̅ m at T ≥ 948 K. Lattice parameters and Mn-O bond distances, obtained by Rietveld refinement, have been used to derive the s...

Positron annihilation lifetime spectroscopy (PALS) has indicated that Nb2O5‐doped TiO2 samples treated in either Ar or air at 1400°C for 48 h are both charge‐compensated by Ti vacancies, but with statistically significant differences between the results. A Ta2O5‐doped air‐sintered TiO2 sample also showed behavior similar to the Nb2O5‐doped air‐sint...

We present the neutron and synchrotron x-ray diffraction and Ce L3-edge x-ray absorption near-edge structure results for polycrystalline La2Ce2O7. We have found that this compound adopts a disordered defect fluorite structure with diffuse features evident in the neutron-diffraction pattern indicative of anion disorder. Our experimental results are...

A series of uranium-containing gadolinium zirconate samples have been fabricated at 1723 K in air. X-ray diffraction and Raman spectroscopy have confirmed pyrochlore or defect fluorite structures, while diffuse reflectance, X-ray absorption near edge structure and X-ray photoelectron spectroscopies indicate a predominantly U6+ oxidation state, even...

Electronic parameters of a suite of hexavalent uranium compounds measured with X-ray photoelectron spectroscopy (XPS) have been collected. The binding energy difference, ΔBE = BE (O 1s) – BE (U 4f7/2), was used to characterize the valence electron transfer on the formation of the U–O bonds. The chemical bonding effects were considered on the basis...

Neutron diffraction methods are used to refine the structure of SrRu(0.8)Ni(0.2)O(3) at room temperature and 4 K. X-ray absorption measurements at the Ru L-edge demonstrate that partial oxidation of the Ru(4+) to Ru(5+) occurs upon introducing Ni into the SrRuO(3) structure to form SrRu(0.8)Ni(0.2)O(3). Whilst the diffraction measurements show that...

Chemical bonding effects have been discussed for anhydrous niobates and tantalates using binding energy differences Delta(Nb) = (BE O 1s - BE Nb 3d(5/2)) and Delta(Ta) = (BE O 1s - BE Ta 4f(7/2)) as key parameters to relate structural and electronic properties of these dielectric oxides. Such known photocatalytic materials as K4Nb6O17, Sr2Nb2O7, Ta...

The structure of TcCo(2)O(4) has been determined using a combination of synchrotron X-ray and neutron powder diffraction methods. It has an inverse spinel structure where the Tc occupies the octahedral sites. Both the refined Tc-O distance and X-ray absorption spectra suggest the Tc is predominantly trivalent.

We demonstrate that water is almost universally present on apparently dry self-assembled monolayers, even on those considered almost hydrophobic by conventional methods such as water contact goniometry. The structure and kinetics of nanoscale water adsorption onto these surfaces were investigated using X-ray and neutron reflectometry, as well as at...

Structural properties of anhydrous Nb 5+-niobates and Ta 5+-tantalates have been evaluated with the help of classic polyhedra approach and atomic net model. X-ray photoelectron spectroscopy (XPS) is utilized as a powerful method to determine the binding energy (BE) of individual atoms in the crystal lattice. Chemical bonding effects are discussed f...

Two Bax CsyMnzTi8-zO 16 hollandite samples, containing excess rutile, have been prepared, targeting the Mn valence as 3+ by sintering at 1300°C in air (z = 2x +y) and as 2+ (z = x + y/2) in argon. SEM showed the sample sintered in air to contain major hollandite and minor Mn titanate and rutile. The sample sintered in argon contain major hollandite...

We have studied the aqueous durability of pyrochlore-structured yttrium-titanate (Y2Ti2O7) and Nd/Al-bearing zirconolite [(Ca0.8Nd0.2)Zr(Ti1.8Al 0.2)O7] in both neutral and acidic solutions, with and without the presence of 0.001 M of NaF. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Atomic...

Static dissolution tests on Nd-bearing zirconolite were conducted in deionized water at 150°C for up to 6 months. Surfaces, both before and after aqueous dissolutions, were examined using X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Individual submicron-sized crystals were observed only on some zirconolite grains a...

We have carried out Ce L- and Mn K-edge x-ray absorption near edge structure (XANES) measurements to experimentally determine the oxidation states of both Ce and Mn in (Sr(1 - x)Ce(x))MnO(3) (x = 0.1-0.4). It was found that although Ce is predominantly 4 + at low doping levels (x = 0.1 and 0.15), the Ce valency decreases with increasing Ce doping (...

The title compounds are synthesized by solid state reaction of stoichiometric mixtures of La2O3, Rh, and Mn2O3 or CuO (1300 °C, 6 d) and characterized by XANES and powder synchrotron X-ray and neutron diffraction.

XPS measurements were carried out on Sr₂Nb₂O₇ and Sr₂Ta₂O₇ powder samples, which were synthesized using standard solid state method. The binding energy differences between the O 1s and cation core level, Δ(O-Sr) = BE(O 1s) - BE(Sr 3d_5/2), was used to characterize the valen...

The structure and properties of Sr1-xCaxRu0.5Mn0.O-5(3) compositions have been investigated. Both bond distances and X-ray absorption measurements reveal Mn3+ + Ru5+ <-> Mn4+ + Ru4+ mixed valency across the entire series. Despite a complete lack of Ru/Mn chemical order, all samples magnetically order between 220 and 300 K. The characteristics and t...

Analysis of multiphase (Ca,U) titanate pyrochlore samples produced under argon or in air, using laboratory X-ray powder diffraction (XRD) and electron microscopy revealed discrete pyrochlore phase compositions, together with either perovskite or rutile impurities. Investigations of these samples using diffuse reflectance and X-ray photoelectron spe...

a b s t r a c t Diffuse reflectance measurements were made over the wavenumber range of 4000–20,000 cm À1 at room temperature on monoclinic and stabilised ZrO 2 , together with Y 2 Ti 2 O 7 having the pyrochlore structure, all of which were doped with U and sintered in various atmospheres. X-ray photoelectron spectroscopy measurements were also car...

Diffuse reflectance measurements were made over the wavenumber range of 4000–20,000 cm−1 at room temperature on monoclinic and stabilised ZrO2, together with Y2Ti2O7 having the pyrochlore structure, all of which were doped with U and sintered in various atmospheres. X-ray photoelectron spectroscopy measurements were also carried out on selected sam...

The two orthorhombic perovskites LaMn0.5Rh0.5O3 and LaCu0.5Rh0.5O3 have been characterized using X-ray absorption near edge structure (XANES) measurements and powder synchrotron X-ray and neutron diffraction The Mn and Rh in LaMn0.5Rh0.5O3 are essentially trivalent and disordered onto the same crystallographic site The absence of an appreciable Jah...

The structural and magnetic properties of Sr(1-x)Ca(x)Mn0.5Ru0.5O3 have been investigated. SrMn0.5Ru0.5O3 exhibits antiferromagnetic ordering, TN 200 K. Neutron powder diffraction of this perovskite indicates the presence of orbital ordering of the occupied Mn^+3 dz2 orbitals, stabilizing the spin ordering corresponding to the AFM C-type structure....

X-ray absorption and magnetic circular dichroism measurements have been carried out on stainless steel 316 samples, both before and after He+-ion irradiation. It was found that Fe and Cr were both oxidised in the surface layer due to exposure to ambient with the Cr oxidation layer running deeper into the sample. Irradiation with He+ ions apparently...

X-ray photoelectron spectroscopy was used to detect an intergranular impurity film in two (BaxCsy)(MnzTi8−z)O16 hollandite samples sintered in argon and air, respectively. This impurity film is enriched in Cs and Ba, as a result of segregation during high-temperature processing. The Cs ions in the grain-boundary layer have a different chemical bond...

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Eleven members of the series CaRu1−xMnxO3 with 0 ≤ x ≤ 1 have been prepared and characterized using a combination of Mn K-edge and Ru L3,2-edge X-ray absorption near edge structure spectroscopy and high resolution synchrotron X-ray powder diffraction. A complex distribution of four Mn3+/4+ and Ru4+/5+ oxidation states was observed and quantified. W...

Electronic parameters of constituent element core levels of strontium pyrotantalate (Sr2Ta2O7) were measured with X-ray photoelectron spectroscopy (XPS). The Sr2Ta2O7 powder sample was synthesized using standard solid state method. The valence electron transfer on the formation of the Sr–O and Ta–O bonds was characterized by the binding energy diff...

Fifteen perovskite-type compounds Sr0.9−xCaxCe0.1MnO3, x=0–0.9 in steps as fine as 0.05, have been synthesised by solid state methods, and the room temperature structures characterised using X-ray synchrotron powder diffraction. At low Ca contents (x⩽0.45) the structures are tetragonal in space group I4/mcm and at high Ca contents (x⩾0.55) the comp...

We have studied the crystal structures of (Sr(0.8)Ce(0.2))(Mn(1-y)Co(y))O(3) (y = 0 and 0.2) using neutron diffraction. Both (Sr(0.8)Ce(0.2))MnO(3) and (Sr(0.8)Ce(0.2))(Mn(0.8)Co(0.2))O(3) have a tetragonal structure in space group I4/mcm at room temperature, and the octahedral tilt angle around the c-axis is nearly the same. The only significant d...