Environmental SEM monitoring of Ce1−xLnxO2−x/2mixed-oxide microstructural evolution during dissolution

Horlait, Denis; Claparède, Laurent; Tocino, Florent; Clavier, Nicolas; Ravaux, Johann; Szenknect, Stéphanie; Podor, Renaud

doi:10.1039/c3ta14623e

Cited by 55 publications

(31 citation statements)

References 53 publications

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“…Sample corners were constantly monitored by taking pictures every second during the first 5 min of the experiments, every 5 s after 5 min up to 2 h and every 30 s after 2 h up to 16 h. All images were recorded with the same field of view corresponding to 1050 lm squared. General procedure and details about the HT-ESEM platform can be found in refs [26][27][28].…”

Section: Methodsmentioning

confidence: 99%

Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization

et al. 2016

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Oxidation of dense hot-pressed ZrC specimens from 1073 to 1473 K was investigated using an in situ technique: HT-ESEM. Cuboid specimens were monitored on the surface and on edges and corners during oxidation in order to understand the influence of crack formation and propagation on the Maltese cross shape development of the oxide. The oxidation mechanism comprised three steps: (1) delamination of sample edges, (2) crack formation at corners and (3) crack propagation towards the inner core and formation of microcracks parallel to the interface that increase the accessible surface area followed by a drastic volume expansion. The microcrack pattern is found to be repetitive as if a cyclic debonding of the interface occurred. Characterization of the interface by TEM and HRTEM revealed 123Oxid Met (2017) 88:509-519 DOI 10.1007 the interface between ZrC and ZrO 2 to comprise a 2 lm thick amorphous carbon matrix with ZrO 2 nanocrystals embedded in it.

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Section: Methodsmentioning

confidence: 99%

Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization

et al. 2016

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“…All images were recorded with the same field of view, corresponding to an area of 908 × 836 μm 2 . The general procedure and details of the HT-ESEM platform may be found in refs 30,31,32 . Image analysis, using the Fiji ImageJ 33 software, was used to monitor surface changes during isothermal heat treatments.…”

Section: Methodsmentioning

confidence: 99%

Oxidation of UC: An in situ high temperature environmental scanning electron microscopy study

Gasparrini

Podor

Horlait

et al. 2017

Journal of Nuclear Materials

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Abstract. In situ HT-ESEM oxidation of sintered UC fragments revealed the morphological changes occurring during the transformation between UC to UO2 and UO2 to U3O8 at 723 to 848 K and in an atmosphere of 10 to 100 Pa O2. Two main oxidation pathways were revealed. Oxidation at 723 K in atmospheres ≤ 25 Pa O2 showed the transformation from UC to UO2+x, as confirmed by post mortem HRTEM analysis. This oxidation pathway was comprised of three steps: (i) an induction period, where only surface UC particles oxidised, (ii) a sample area expansion accompanied by crack formation and propagation, (iii) a stabilisation of the total crack length inferring that crack propagation had stopped. Samples oxidised under 50 Pa O2 at 723 K and at 773 -848 K for 10 to 100 Pa O2 showed an "explosive" oxidation pathway: (i) sample area expansion occurred as soon as oxygen was inserted into the chamber and crack propagation and crack length followed an exponential law; (ii) cracks propagated as a network and the oxide layer fragmented, (iii) an "explosion" occurred causing a popcorn-like transformation, typical for oxidation from UO2 to U3O8. HRTEM characterisation revealed U3O8 preferentially grow in the [001] direction. The explosive growth, triggered by ignition of UC, proceeded as a self-propagating high-temperature synthesis reaction, with a propagation speed of 150-500 ± 50 µm/s.

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“…6(a) and (b) that the normalized elemental leach rates of Ce and Gd in both samples gradually decrease with increasing leaching time before 21 days. Horlait [43] studied the microstructural evolution of several sintered Ce 1À x Ln x O 2À x/2 pellets during their dissolution, and reported that grain boundaries were relative weakness and dissolved easily. Here, we deduced that the normalized elemental leach rate might be affected by grain boundaries of samples before 21 days.…”

Section: Chemical Durabilitymentioning

confidence: 99%

Comparison of microstructure and chemical durability of Ce0.9Gd0.1PO4 ceramics prepared by hot-press and pressureless sintering

Zhao

Teng

Yang

et al. 2015

Ceramics International

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Environmental SEM monitoring of Ce_1−xLn_xO_2−x/2mixed-oxide microstructural evolution during dissolution

Abstract: Evolution of sintered Ce1−xLnxO2−x/2samples during dissolution tests in acidic media was followed in the same zone by environmental scanning microscopy.

Cited by 55 publications

References 53 publications

Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization

Zirconium Carbide Oxidation: Maltese Cross Formation and Interface Characterization

Oxidation of UC: An in situ high temperature environmental scanning electron microscopy study

Comparison of microstructure and chemical durability of Ce0.9Gd0.1PO4 ceramics prepared by hot-press and pressureless sintering

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