Thermochromatographic studies of plutonium oxides

2008 ◽  
Vol 96 (12) ◽  
Author(s):  
S. Hübener ◽  
S. Taut ◽  
A. Vahle ◽  
Gert Bernhard ◽  
Thomas Fanghänel
Keyword(s):  
Solid Solutions ◽  
Silica Glass ◽  
Surface Reaction ◽  
Carrier Gas ◽  
Competitive Reactions ◽  
Actinide Oxides ◽  
Glass Columns ◽  
Good Agreement

AbstractTrace amounts of oxidic plutonium species were studied by thermochromatography in silica glass columns in comparison to oxidic species of Th, Pa, U, Np, and Am. Humid oxygen was used as reactive admixture to the carrier gas helium. The thermochromatographic behavior of plutonium provides evidence for the oxidation of Pu(IV) to Pu(VI) with humid oxygen. The gas chromatographic transport of U, Np, and Pu is governed by the surface reactionMOwith M=U, Np, and Pu in the hexavalent state and competitive reactions of the actinide oxides with silica to nonvolatile compounds or solid solutions. There is good agreement with earlier volatility studies and the reported oxidation of PuO

PHREEQC Modelling of Leaching of Major Elements and Heavy Metals From Cementitious Waste Forms

2008 ◽  
Vol 1107 ◽  
Author(s):  
Evelien Martens ◽  
Diederik Jacques ◽  
Tom Van Gerven ◽  
Lian Wang ◽  
Dirk Mallants
Keyword(s):  
Solid Solutions ◽  
Bottom Ash ◽  
Major Elements ◽  
Cementitious Material ◽  
Waste Incinerator ◽  
Waste Forms ◽  
Phreeqc Modelling ◽  
Single Set ◽  
Good Agreement ◽  
Mineralogical Phases

AbstractIn this study, Ca, Mg, Al, and Pb concentrations leached from uncarbonated and carbonated ordinary Portland cement – dried waste incinerator bottom ash samples during single extraction tests (EN12457 test) at a pH from 1 to 12, were modelled using the geochemical code PHREEQC. A good agreement was found between modelling results and experiments in terms of leached concentrations for Ca, Mg, and Al by defining a single set of pure mineralogical phases for both the uncarbonated and carbonated (three levels) samples. The model also predicted well the observed decrease in Ca leaching with increasing carbonation. Modelling results further revealed that leaching of Pb is not controlled by dissolution/precipitation of pure Pb containing minerals only (carbonates and (hydr)oxides). The addition of solid solutions (calcite-cerrusite and gibbsite-ferrihydrite-litharge solid solutions) and adsorption reactions on amorphous Fe- and Al-oxides improved the model representation of the experimentally observed amphoteric leaching profile of Pb from the cementitious material.

scholarly journals FABRICATION AND PROPERTIES OF Co DOPED Bi0.5K0.5TiO3 – BiFeO3 SOLID SOLUTION

2018 ◽  
Vol 56 (1A) ◽  
pp. 197
Author(s):  
Nguyen Hoang Tuan
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Magnetic Properties ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Sol Gel ◽  
Structure And Properties ◽  
Antiferromagnetic Ordering ◽  
Co Doped ◽  
Good Agreement

In this study, we present some results on the structure and properties of the solid solution of Bi0.5K0.5TiO3– BiFeCoO3 (BKT – BFCO) by Sol-gel method. Crystal structures of BKT – BFCO solid solutions were studies by XRD and Raman spectroscopy. The results were in good agreement with the previous reports of Bi0.5K0.5TiO3– BiFeO3 (BKT – BFO) and Bi0.5K0.5TiO3 – BiCoO3 (BKT – BCO) solid solutions. The magnetic properties were investigated via unsaturated M-H loop, which showed the competition of paramagnetic and antiferromagnetic ordering in BKT – BFCO. However, differing from the BKT – BFO and BKT – BCO solid solutions, the unclear values of saturated magnetism in BKT – BFCO raised the unexplained question, which needed further studies.

The constitution of alloys of iron and manganese with transition elements of the first long period

1957 ◽  
Vol 249 (968) ◽  
pp. 417-459 ◽  
Keyword(s):  
Solid Solutions ◽  
Iron Alloys ◽  
Continuous Series ◽  
Size Factor ◽  
General Effect ◽  
Transition Elements ◽  
Two Phase ◽  
Phase Liquid ◽  
The Stability ◽  
Good Agreement

Using metals of the highest purity, the constitutions of iron-rich and manganese-rich binary alloys with the sequence of elements Ti-V-Cr-(Mn, Fe)-Co-Ni-Cu have been investigated by specially accurate thermal analysis, supplemented by microscopical and X-ray work. The liquidus and solidus curves have been determined accurately, and also the forms of the A 4 (Y/O) transformations in the iron alloys, and of the (Y/O) and (Y/B) transformations in the manganese alloys. The complete liquidus and solidus were determined for the system Fe—Mn, and the equilibrium diagrams of the systems Fe-Ti and Mn-Ti were studied as far as 52 at. % Ti. O-Mn (b.c.c.) and y-Mn (f.c.c.) have the same crystal structures as O-Fe and y-Fe respectively, and the corresponding parts of the equilibrium diagrams are thus structurally comparable. In general, there is a remarkable correspondence between the effects of the different elements in stabilizing the b.c.c. or f.c.c. phases. The closed y-loops in the systems Fe-Ti, Fe—V and Fe-Cr are paralleled by closed y-fields in the Mn alloys, whilst Mn (in Fe), Fe (in Mn) and Ni produce open or expanded y-fields; Cu behaves abnormally in both series of alloys. In the Mn alloys, the stability and range of the B-Mn phase reach a maximum in the system Mn-Co, where the B-Mn phase is so stable that it comes into equilibrium with the liquid, and prevents the formation of a continuous series of solid solutions between Y-Mn and B-Co (f.c.c.). For the iron alloys the size factors are favourable for all the solutes examined, except Ti, which lies on the borderline of the favourable zone. With O-Mn and Fe-Mn as solvents, the size factors are all favourable, although that for Ti is still appreciable ( ca. 10%). The effect of size factor is shown by steep depression of the O-liquidus and O-solidus curves in the systems Fe-Ti and Mn—Ti. For the iron alloys the relative depressions of liquidus and solidus at equal atomic percentages of solute are in the order Ti > V > Cr and Co < Ni < Cu, and these sequences are the same as those for the lattice distortions produced by equiatomic percentages of the same solutes; the effect of Mn lies out of sequence in both cases. These and other relations are discussed. When compared with previous diagrams, the general effect of the present work is to indicate a much narrower two-phase (liquid and solid) range for both O-Fe and Y-Fe solid solutions. In marked contrast to previous diagrams, the present liquidus and solidus curves can all be reconciled with the existence of monatomic solutions in both liquid and solid phases. For Fe-Mn alloys the equations for dilute solutions are in good agreement with thermal data for pure iron up to 30 at. % Mn.

Size Effects in Bi-Sb Solid Solutions Thin Films

2011 ◽  
Vol 1314 ◽  
Author(s):  
Elena I. Rogacheva ◽  
Dar’ya S. Orlova ◽  
Mildred S. Dresselhaus ◽  
Shuang Tang
Keyword(s):  
Thin Films ◽  
Solid Solutions ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Theoretical Calculations ◽  
Thermoelectric Power Factor ◽  
Quantum Oscillations ◽  
Kinetic Coefficients ◽  
Temperature Dependences ◽  
Good Agreement

ABSTRACTThe room-temperature dependences of the electrical conductivity σ, Seebeck coefficient S, Hall coefficient RH, and the thermoelectric power factor P on the thickness (d=10–300 nm) of the thin films grown on mica substrates by thermal evaporation in vacuum of Bi-Sb solid solutions crystals with 4.5 at.% Sb were obtained. It was established that an increase in d up to ~ 200 nm leads to a change in kinetic coefficients and that in the thickness dependences of the thermoelectric properties, quantum oscillations were observed. It was shown that the monotonic component of the σ(T) dependence can be satisfactorily approximated by theoretical calculations based on the classical Fuchs - Sondheimer theory. The theoretically estimated period of oscillations is in a good agreement with the experimentally observed period.

First Principle Study of the Diffusion of Oxygen and Oxygen Complexes in Si, SiGe Solid Solutions and Si Nanocrystals

2013 ◽  
Vol 205-206 ◽  
pp. 171-180 ◽  
Author(s):  
Vasilii Gusakov
Keyword(s):  
Diffusion Coefficient ◽  
Solid Solutions ◽  
Activation Barrier ◽  
Interstitial Oxygen ◽  
Silicon Nanotubes ◽  
Silicon Crystals ◽  
Si Nanocrystals ◽  
Equilibrium Structures ◽  
Oxygen Complexes ◽  
Good Agreement

In the framework of a unified approach the diffusion coefficient (the prefactor and activation barrier) of an interstitial oxygen Oi, the hydrogen molecule H2, vacancy, oxygen dimer in silicon crystals and Oiin Si1-xGexsolid solutions, silicon nanotubes and nanowires has been calculated. For all the above cases, the calculated values of the diffusion coefficient are in good agreement with the experimental data. The calculated equilibrium structures, electrical activity, the vibrational spectrum, the mechanism of diffusion of oxygen dimer fully describe the experimental results. Our study has revealed that the diffusivity of impurities (defects) in alloys can decrease considerably and this variation results from the fact that the prefactor depends on the concentration of component elements of the alloy.

Study of Electrical Conductivity in WO3-doped Nonstoichiometric LiTaO3

2012 ◽  
Vol 57 (8) ◽  
pp. 834
Author(s):  
M. Tahiri ◽  
N. Masaif ◽  
A. Jennane ◽  
E.M. Lotfi
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Ternary System ◽  
Curie Temperature ◽  
Solid Solutions ◽  
Theoretical Approach ◽  
Defect Structure ◽  
Experimental Conductivity ◽  
Theoretical Results ◽  
Good Agreement

The results of experimental and analytical studies of the electrical conductivity for different solid solutions synthesized in a vicinity of LiTaO3 in the ternary system Li2O–Ta2O5–(WO3)2 are presented. It is shown that the electrical conductivity increases linearly with the Curie temperature. The experimental conductivity between 200 and 700 ºC was measured using an LCR bridge HP4192A on ceramics sintered at 1250 ºC. Within the theoretical approach to the defect structure analysis combined with our proposed vacancy models, the theoretical results are in a good agreement with the experimental data.

Local mean chromium–oxygen distances in Cr3+-centered octahedra of natural grossular-uvarovite garnet solid solutions from electronic absorption spectra

2004 ◽  
Vol 219 (5) ◽  
Author(s):  
Klaus Langer ◽  
Alexej N. Platonov ◽  
Stanislav S. Matsyuk
Keyword(s):  
Crystal Field ◽  
Absorption Spectra ◽  
Solid Solutions ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Crystal Field Parameter ◽  
Field Parameter ◽  
Local Mean ◽  
Good Agreement

AbstractThe crystal field parameter 10Dq10DqThe 10DqEquation (a) is in very good agreement with mean 〈Al/Cr—O〉; distances of “individual” octahedra

scholarly journals EFFECT OF CARRIER GAS FLOW RATE AND COLUMN TEMPERATURE ON THE SUITABILITY PARAMETERS OF GC-ECD FOR SF6 MEASUREMENT

2017 ◽  
Vol 14 (28) ◽  
pp. 120-129
Author(s):  
Oman ZUAS
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Theoretical Plate ◽  
Gas Flow Rate ◽  
Column Temperature ◽  
Carrier Gas ◽  
System Suitability ◽  
Carrier Gas Flow ◽  
Asymmetric Factor ◽  
Good Agreement

System suitability testing of a GC is essential to verify its suitability for intended application. The GC always uses a carrier gas and column temperature, which may impact on its suitability parameters. This study is aimed to evaluate the effects of carrier gas flow rate (FLRT) and column temperature (CLTP) on the system suitability parameters (SSP) of GC-ECD for SF6 measurement such as retention time/tR, response factor/RF, theoretical plate numbers/N, and asymmetric factor/As. The evaluation was conducted by carefully profiling the SF6 chromatogram and the data obtained were used to calculate the tR, RF, N, and As values. It was found that the tR increases linearly (R2 = 0.9978) by increasing the FLRT, but decreases linearly (R2 = 0.9991) by increasing the CLTP. The RF decreases linearly (R2 = 0.9939) by increasing the FLRT. Interestingly, the RF was affected by the CLTP with 2nd polynomial order trend (R2 = 0.9949). The N increases linearly (R2 = 0.9404) by increasing the FLRT but the N was affected b the CLTP with 2nd polynomial order trend (R2 = 0.9769). The As was found to increase slightly with FLRT (R2 = 0.1288), while the As was affected by the CT with 2nd polynomial order trend (R2 = 0.9778). These results are in a good agreement with previous SSP studies.

scholarly journals Advancing the Production Routes of Nanosized Actinide Oxides Solid Solutions

2019 ◽  
Author(s):  
Karin Popa ◽  
Olaf Walter ◽  
Oliver Dieste Blanco ◽  
Daniel Bouëxière ◽  
Jean-François Vigier ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Actinide Oxides

The Phase Stability in the Fe-B Binary System: Comparison between the Interstitial and Substitutional Models

2012 ◽  
Vol 322 ◽  
pp. 1-9 ◽  
Author(s):  
Z. Nait Abdellah ◽  
Redoune Chegroune ◽  
Mourad Keddam ◽  
B. Bouarour ◽  
L. Haddour ◽  
...  
Keyword(s):  
Binary System ◽  
Phase Diagrams ◽  
Solid Solutions ◽  
Phase Stability ◽  
Thermodynamic Stability ◽  
Thermodynamic Study ◽  
Thermodynamic Calculations ◽  
Chemical Potentials ◽  
Two Phases ◽  
Good Agreement

In the present work, a thermodynamic study was carried out in order to analyze the thermodynamic stability of the and phases in equilibrium with the phase using the calculation of phase diagrams (Calphad) formalism. The two phases and are modelled as substitutional and interstitial solid solutions of boron. The expressions of the chemical potentials ofBandFeare derived in both phases to perform the thermodynamic calculations. A comparison is made between the results provided by the substitutional and interstitial models and good agreement is observed between these two models.

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