Flash sintering of stoichiometric and hyper-stoichiometric urania

Valdez, James A.; Byler, Darrin D.; Kardoulaki, Erofili; Francis, John S. C.; McClellan, K. J.

doi:10.1016/j.jnucmat.2018.03.049

Cited by 14 publications

(8 citation statements)

References 39 publications

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“…Displacement sensor: it allows to measure the sample shrinkage, associated to densification and sintering (Figure 4); it consists typically of a (CCD) camera [11,36] or of a LVDT, this latter being often part of a dilatometer [37,82,[91][92][93].…”

Section: Equipmentmentioning

confidence: 99%

Flash sintering of ceramics

Biesuz

Sglavo

2019

Journal of the European Ceramic Society

341

208

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Section: Equipmentmentioning

confidence: 99%

Flash sintering of ceramics

Biesuz

Sglavo

2019

Journal of the European Ceramic Society

341

208

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“…UO x is arguably one of the most complex binary metal oxides because of its changeable valence (and/or mixed-valence) orbital configurations under different environmental conditions. UO 2 exhibits a cubic Fm 3̅ m structure with a lattice parameter a = 5.471 Å and is susceptible to redox related nonstoichiometry, with oxygen ion defects or interstitials accommodated in the lattice, commonly denoted as UO 2± x . , UO 2 is a semiconductor (UO 2+ x is p-type, UO 2– x is n-type) with a first-order phase transition to the antiferromagnetic state at T N = 30.8 K. At room temperature, two crystalline forms of (α, β)-U 3 O 8 have been reported. It has been reported that α-U 3 O 8 has a pseudohexagonal orthorhombic structure with the space group of C 2 mm ( a = 6.716 Å, b = 11.960 Å, and c = 4.147 Å) .…”

Section: Resultsmentioning

confidence: 99%

Structural and Optical Properties of Phase-Pure UO₂, α-U₃O₈, and α-UO₃ Epitaxial Thin Films Grown by Pulsed Laser Deposition

Enriquez

Wang

Sharma

et al. 2020

ACS Appl. Mater. Interfaces

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Fundamental understanding of the electronic, chemical, and structural properties of uranium oxides requires the synthesis of high-crystalline-quality epitaxial films of different polymorphs of one material or different phases with various oxygen valence states. We report the growth of single-phase epitaxial UO2, α-U3O8, and α-UO3 thin films using pulsed laser deposition. Both oxygen partial pressure and substrate temperature play critical roles in determining the crystal structure of the uranium oxide films. X-ray diffraction and Raman spectroscopy demonstrate that the films are single phase with excellent crystallinity and epitaxially grown on a variety of substrates. Chemical valance states and optical properties of epitaxial uranium oxide films are studied by X-ray photoelectron spectroscopy and UV–vis spectroscopy, which further confirm the high-quality stoichiometric phase-pure uranium oxide thin films. Epitaxial UO2 films show a direct band gap of 2.61 eV, while epitaxial α-U3O8 and α-UO3 films exhibit indirect band gaps of 1.89 and 2.26 eV, respectively. The ability to grow high-quality epitaxy actinide oxide thin films and to access their different phases and polymorphous will have significant benefits to the future applications in nuclear science and technology.

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“…RFS tests were performed in a dilatometer (DIL 402C from Netzsch) that was adapted by inserting two platinum electrodes into its furnace chamber, as described elsewhere. 47,48 Two power supplies were used in this study, one for DC fields (N5772A from Keysight) and another for AC fields set at 16 Hz (AST1501 from California Instruments). The bottom and top surfaces of the 0.8(ZrO 2 )+0.2(CeO 2 ) pellets were painted with platinum paint to improve the electrical contact between pellet and electrodes.…”

Section: Methodsmentioning

confidence: 99%

“…RFS tests were performed in a dilatometer (DIL 402C from Netzsch) that was adapted by inserting two platinum electrodes into its furnace chamber, as described elsewhere 47,48 . Two power supplies were used in this study, one for DC fields (N5772A from Keysight) and another for AC fields set at 16 Hz (AST1501 from California Instruments).…”

Section: Methodsmentioning

confidence: 99%

The influence of the processing parameters on the reactive flash sintering of ZrO₂‐CeO₂

2022

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Reactive flash sintering (RFS) is a method that was recently developed to produce dense single‐phase bulk ceramic parts through solid‐state reactions in a single‐step that only takes a few minutes. The influence of the RFS parameters on the phase purity of a simple mixed oxide, (Zr0.8,Ce0.2)O2, was investigated. Parameters such as furnace temperature, furnace atmosphere, electric current density, and alternating current (AC) or direct current (DC) were examined. It was found that (Zr0.8,Ce0.2)O2 pellets with high densities, above 90% of its theoretical density, can be produced by RFS in a few minutes when RFS occurs under oxidizing atmospheres, AC fields with current densities of 100 mA·mm−2, and at a furnace temperature of 1200°C. Reducing conditions such as Ar‐H2 atmosphere and DC fields, low furnace temperatures, and low current densities resulted in phase impurities and poor reactions between the ZrO2 and the CeO2 powders. These results show that RFS is a useful method to produce mixed oxides, but it is very sensitive to the processing parameters. This is the first time that the influence of most of the RFS processing parameters has been studied systematically. Thus, the present work aims to provide guidelines on selecting the right processing parameters when exploring RFS.

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Flash sintering of stoichiometric and hyper-stoichiometric urania

Cited by 14 publications

References 39 publications

Flash sintering of ceramics

Flash sintering of ceramics

Structural and Optical Properties of Phase-Pure UO₂, α-U₃O₈, and α-UO₃ Epitaxial Thin Films Grown by Pulsed Laser Deposition

The influence of the processing parameters on the reactive flash sintering of ZrO₂‐CeO₂

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Flash sintering of stoichiometric and hyper-stoichiometric urania

Cited by 14 publications

References 39 publications

Flash sintering of ceramics

Flash sintering of ceramics

Structural and Optical Properties of Phase-Pure UO2, α-U3O8, and α-UO3 Epitaxial Thin Films Grown by Pulsed Laser Deposition

The influence of the processing parameters on the reactive flash sintering of ZrO2‐CeO2

Contact Info

Product

Resources

About

Structural and Optical Properties of Phase-Pure UO₂, α-U₃O₈, and α-UO₃ Epitaxial Thin Films Grown by Pulsed Laser Deposition

The influence of the processing parameters on the reactive flash sintering of ZrO₂‐CeO₂