Effect of Molybdenum and Ruthenium on the Crystallization Tendency of a New Nuclear Glass Containing High Rare-earth Concentration

2010 ◽  
Vol 1265 ◽  
Author(s):  
Daniel Caurant ◽  
Nolwenn Chouard ◽  
Odile Majerus ◽  
Jean-Luc Dussossoy ◽  
Aurelien Ledieu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Nucleating Agent ◽  
High Level Waste ◽  
Optical Absorption Spectroscopy ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Level ◽  
The Impact ◽  
Crystallization Tendency

AbstractThe impact of Nd2O3, MoO3 and RuO2 addition on the competition between the crystallization of apatite Ca2Nd8(SiO4)6O2 and powellite CaMoO4 phases which both may appear in High Level Waste nuclear glass (under certain specific conditions of cooling and glass composition) has been studied on a simplified composition belonging to the system SiO2-Na2O-CaO-Al2O3-B2O3. X-ray diffraction (at room temperature and high temperature) and scanning electron microscopy measurements have been performed on five glasses under two different thermal treatments. We show that RuO2 acts as a nucleating agent for apatite. Moreover, neodymium and molybdenum cations seem to be very close in the glassy network as Nd2O3 addition stops the phase separation of molybdates and inhibits the crystallization of CaMoO4. On the contrary, MoO3 seems to favor the crystallization of apatite. For several samples, the evolution of the distribution of Nd3+ cations after crystallization was followed by optical absorption spectroscopy.

Study on Mechanical Properties of PP Modified by β Nucleating Agent under the Low Temperature

2013 ◽  
Vol 710 ◽  
pp. 97-101
Author(s):  
Jiang Zhu ◽  
Xiang Liu ◽  
Qiang Xu ◽  
Liang Cao
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Room Temperature ◽  
Bending Strength ◽  
Nucleating Agent ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Elongation At Break ◽  
X Ray ◽  
The Impact

The ethylene-propylene polymer (PP) was modified by using a rare earth β-nucleating agent (WBG-II). The crystallization characteristics of PP induced by WBG-II were investigated through the wide-angle X-ray diffraction (WAXD). The effect of β-nucleating agent on the mechanical property of PP under low temperature was also researched. The results confirmed that β-nucleating agent WBG-II can change the crystal structure of PP and induce the β-form crystals in the PP to develop. Moreover, under the room temperature, with the increment of WBG-II, the tensile strength, bending strength and modulus of the modified PP increase, but the impact strength and elongation at break decrease; and especially at-10 °C, this tendency is more obvious.

Effect of Li, Fe, and B Addition on the Crystallization Behavior of Sodium Aluminosilicate Glasses as Analogues for Hanford High Level Waste Glasses

MRS Advances ◽  
2016 ◽  
Vol 2 (10) ◽  
pp. 549-555 ◽  
Author(s):  
José Marcial ◽  
Mostafa Ahmadzadeh ◽  
John S. McCloy
Keyword(s):  
Function Analysis ◽  
High Level Waste ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Sodium ◽  
Chemical Ordering ◽  
Sodium Aluminosilicate ◽  
Aluminosilicate Glasses ◽  
Heat Treated ◽  
High Level

ABSTRACTCrystallization of aluminosilicates during the conversion of Hanford high-level waste (HLW) to glass is a function of the composition of the glass-forming melt. In high-sodium, high-aluminum waste streams, the crystallization of nepheline (NaAlSiO4) removes chemically durable glass-formers from the melt, leaving behind a residual melt that is enriched in less durable components, such as sodium and boron. We seek to further understand the effect of lithium, boron, and iron addition on the crystallization of model silicate glasses as analogues for the complex waste glass. Boron and iron behave as glass intermediates which allow for crystallization when present in low additions but frustrate crystallization in high additions. In this work, we seek to compare the average structures of quenched and heat treated glasses through Raman spectroscopy, X-ray diffraction, vibrating sample magnetometry, and X-ray pair distribution function analysis. The endmembers of this study are feldspathoid-like (LiAlSiO4, NaAlSiO4, NaBSiO4, and NaFeSiO4), pyroxene-like (LiAlSi2O6, NaAlSi2O6, NaBSi2O6, and NaFeSi2O6), and feldspar-like (LiAlSi3O8, NaAlSi3O8, NaBSi3O8, and NaFeSi3O8). Such a comparison will provide further insight on the complex relationship between the average chemical ordering and topology of glass on crystallization.

Cold Crucible Vitrification of U-bearing SRS SB4 HLW Surrogate

2010 ◽  
Vol 1265 ◽  
Author(s):  
Sergey Stefanovsky ◽  
Alexander Ptashkin ◽  
Oleg Knyazev ◽  
Olga Stefanovsky ◽  
James C Marra
Keyword(s):  
High Level Waste ◽  
Cold Crucible ◽  
Savannah River ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Xrd Study ◽  
Processing Facility ◽  
High Level ◽  
River Site

AbstractSavannah River Site Defense Waste Processing Facility (DWPF) Sludge Batch 4 (SB4) high level waste (HLW) simulant at 55 wt % waste loading was produced in the demountable cold crucible and cooled to room temperature in the cold crucible. Appreciable losses of Cs, S and Cl took place during the melting. A second glass sample was subjected to canister centerline cooling (CCC) regime in an alumina crucible in a resistive furnace. X-ray diffraction (XRD) study showed that the glass blocks were composed of vitreous and spinel structure phases. No separate U-bearing phases were found.

Thermal and Chemical Stability of Micron Aluminum Powders Subjected to Gaseous Water

2016 ◽  
Vol 712 ◽  
pp. 241-245
Author(s):  
Sergey V. Zmanovskiy ◽  
Alexander M. Gromov ◽  
Valentina V. Smirnova ◽  
Vadim F. Petrunin ◽  
Jin Chun Kim
Keyword(s):  
Room Temperature ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Aluminum Powders ◽  
X Ray ◽  
The Stability ◽  
Heating Up ◽  
The Impact ◽  
Thermal And Chemical Stability ◽  
Composition Of Products

The paper studies the impact of gaseous water on the stability of micron aluminum powders in time at room temperature using the method of gravimetric analysis. The stability was studied using methods of thermal analysis during heating up to 1200 °С in air. The composition of products was analyzed using X-ray diffraction analysis. It was found out that the stability of micron aluminum powders depends on partial pressure of water vapor: the increase of pressure results in decreased stability of powders. The work gives recommendations for storing micron aluminum powders.

Effect of thermal treatment on the mechanical and viscoelastic response of polypropylenes incorporating a β nucleating agent

2018 ◽  
Vol 51 (6) ◽  
pp. 562-579 ◽  
Author(s):  
K Belkouicem ◽  
A Benarab ◽  
R Krache ◽  
R Benavente ◽  
E Pérez ◽  
...  
Keyword(s):  
Young Modulus ◽  
Nucleating Agent ◽  
Thermal Treatments ◽  
Mechanical Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Good Balance ◽  
X Ray ◽  
Structure Morphology ◽  
Ultimate Properties

The influence of two thermal treatments on the structure, morphology, and ultimate properties exhibited by isotactic polypropylene (iPP), synthesized by conventional Ziegler–Natta iPP (Z-iPP) or metallocene iPP (m-iPP) catalysts, has been investigated in the present work. Novelty of this research consisted in the incorporation of a β nucleating agent in two different contents to the m-iPP. Results attained are compared with those found in the Z-iPP and important differences are observed. Differential scanning calorimetry and X-ray diffraction experiments revealed that coexistence of different crystalline lattices took place depending on the type of iPP: β and α forms were found in the β nucleated Z-iPP specimens, whereas α, β, and γ polymorphs could be developed in the m-iPP with nucleating agent. On the other hand, the iPP glass transition temperature ( Tg) did not exhibit a significant change because of the addition of β nucleant, as deduced from Dynamic Mechanical Thermal Analysis (DMTA) analysis. Moreover, the size and shape of the iPP spherulites was totally changed by the presence of the β agent. This nucleant promoted the formation of smaller spherulites in a greater amount, as demonstrated by optical microscopy. Concerning the mechanical parameters, microhardness, MH, and Young modulus, E, values were in the fast crystallized samples lower than those presented by their slowly cooled counterparts. A good balance in properties was seen for the slowly crystallized m-iPP that incorporated a 5 wt% content in β nucleating agent, this fact being ascribed to the coexistence of the three α, β, and γ polymorphs.

Phase Relations and Chemical Durability of Ceramics in the Pseudo-Binary System: CaZrTi2O7–GdAlO3

2003 ◽  
Vol 807 ◽  
Author(s):  
N. P. Mikhailenko ◽  
A. V. Ochkin ◽  
S. V. Stefanovsky ◽  
O. I. Kirjanova
Keyword(s):  
Electron Microscopy ◽  
Binary System ◽  
Chemical Durability ◽  
Phase Relations ◽  
High Level Waste ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
High Level ◽  
System 1

ABSTRACTPhase relations in a pseudo-binary system (1-x) CaZrTi2O7- x GdAlO3 suggested for immobilization of a zirconium - rare earth – actinide fraction of high level waste were studied with X-ray diffraction and electron microscopy. Zirconolite and perovskite were found to be major phases in the ceramic samples prepared by cold pressing and sintering at 1400 and 1500 °C. At relatively low perovskite content (x < 0.5) zirconolite is the major host for Gd, which is considered as a trivalent surrogate for Am and Cm. At higher perovskite content, perovskite becomes the major host for Gd. Zirconolite is the major host phase for corrosion products (Al, Fe, Ti, Zr). Leach rates of Gd, 238Pu, and 241Am from the ceramics studied are 10−4–10−5 g/(m2d).

Electrodeposition of Zinc from Binary ZnCl2-DMSO2 Molten Electrolyte at Room Temperature

2007 ◽  
Vol 62 (12) ◽  
pp. 754-760
Author(s):  
Chao-Chen Yang ◽  
Min-Fong Shu
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Electrochemical Behaviour ◽  
Close Packing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molten Electrolyte ◽  
Transmission Electron ◽  
Molten Salt Electrolyte ◽  
High Level

The electrochemical behaviour of zinc on copper, platinum, and tungsten working electrodes was investigated in a binary ZnCl2-DMSO2 room temperature molten salt electrolyte in the temperature range of 60 - 80◦C. Various over-potentials, −0.1, −0.2, −0.3, −0.4, and −0.5 V, were chosen as deposition potentials. The nucleation/growth of zinc changed from progressive to instantaneous if the over-potentials increased from low to high level. The surface morphology and crystal structure of the deposited layer were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Moreover, larger grain size and hexagonal close packing of the zinc layer at −0.5 V were observed by transmission electron microscopy (TEM) with electron diffraction mapping.

The crystal structure and temperature dependence of the elpasolite Tl2LiYCl6

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
Drew R. Onken ◽  
Didier Perrodin ◽  
Edith D. Bourret ◽  
Sven C. Vogel
Keyword(s):  
Crystal Structure ◽  
Gamma Rays ◽  
Room Temperature ◽  
Structural Transition ◽  
Radiation Detection ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Industry Standard ◽  
The Impact

Tl2LiYCl6 (TLYC) is an analog to Cs2LiYCl6, which is currently an industry-standard inorganic scintillator for radiation detection with good gamma–neutron discrimination. The presence of thallium (Z = 81) instead of cesium (Z = 55) in the elpasolite structure increases the density of the compound and its stopping power for gamma rays. This work investigates the impact of the Tl atom on the elpasolite structure. Single-crystal X-ray diffraction at room temperature and powder neutron diffraction with temperature control were used to characterize the crystal structure of TLYC between 296 and 725 K. The presence of Tl leads to a distortion of the cubic elpasolite structure at room temperature: a tetragonal P42 crystal structure (space group 77, a = 10.223, c = 10.338 Å) is identified for TLYC at 296 K. A structural transition to the cubic elpasolite Fm 3 m phase (space group 225) is observed at 464 K. The thermal expansion of the material for each crystal direction is well described by a linear relationship, except for the region between 400 and 464 K where the lattice parameters converge.

Solid State Reaction Study Of The System Co-Li2CO3

1996 ◽  
Vol 51 (7) ◽  
pp. 813-820
Author(s):  
A. Marini ◽  
V. Berbenni ◽  
V. Massarotti ◽  
D. Capsoni ◽  
G. Bruni
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Reaction Model ◽  
Lithium Content ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Processes

Abstract A detailed analysis of the reactive processes taking place in Co-Li2CO3 was performed by use of thermogravimetry and X-ray diffraction. A reaction model is proposed which accounts for the nature, stoichiometry, and amount of the phases present, at room temperature, in samples subjected to different thermal treatments. In particular it is shown that the thermal treatment influences substantially the final lithium content and the relative amount of the Li-containing phases. The results obtained for powdered samples are compared with those obtained in a previous work for plaques.

scholarly journals Magnetic Au-Ag-γ-Fe2O3/rGO Nanocomposites as an Efficient Catalyst for the Reduction of 4-Nitrophenol

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 877 ◽  
Author(s):  
Guangyu Lei ◽  
Jingwen Ma ◽  
Zhen Li ◽  
Xiaobin Fan ◽  
Wenchao Peng ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
X Ray Diffraction ◽  
Efficient Catalyst ◽  
Reaction Systems ◽  
X Ray ◽  
Transmission Electron ◽  
The Impact

In this paper, a facile route has been developed to prepare magnetic trimetallic Au-Ag-γ-Fe2O3/rGO nanocomposites. The impact of the preparation method (the intensity of reductant) on the catalytic performance was investigated. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The prepared nanocomposites show fine catalytic activity towards the reduction reaction of 4-nitrophenol (4-NP). The nanocomposites also have superparamagnetism at room temperature, which can be easily separated from the reaction systems by applying an external magnetic field.

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