Preparation of Thoria-Based Powders via Decomposition From Nitrate Solution

Palmer, B.J.F.; Bähen, L.E.; Gin, A.Y.H.; Winegar, J.E.; Celli, Annamaria

doi:10.1051/jphyscol:1986108

Cited by 3 publications

(3 citation statements)

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“…The more promising ones are generally based on the initial precipitation of low-temperature crystallized precursors such as hydroxides [32], carbonates [33], nitrates [34] or oxalates [16,21,35]. These latter, widely studied in the framework of actinide coprecipitation for nuclear fuels refabrication [36,37], are also generally expected to provide interesting properties such as easy and rapid preparation coupled to a high reactivity of the resulting samples [17,18].…”

Section: Introductionmentioning

confidence: 99%

Combining in situ HT-ESEM observations and dilatometry: An original and fast way to the sintering map of ThO2

Clavier

Podor

Deliere

et al. 2013

Materials Chemistry and Physics

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Section: Introductionmentioning

confidence: 99%

Combining in situ HT-ESEM observations and dilatometry: An original and fast way to the sintering map of ThO2

Clavier

Podor

Deliere

et al. 2013

Materials Chemistry and Physics

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“…Among such precursors, carbonates [5], nitrates [6], and more importantly oxalates [7], were particularly investigated and already provided interesting properties such as a rapid preparation of the powders [8,9] and a simple conversion to the desired oxide phase through heat treatment at high temperature. However, the final powders obtained were found to present a contrasted behaviour concerning their sintering capability.…”

Section: Introductionmentioning

confidence: 99%

An original precipitation route toward the preparation and the sintering of highly reactive uranium cerium dioxide powders

Martinez

Clavier

Mesbah

et al. 2015

Journal of Nuclear Materials

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h i g h l i g h t sDense (U,Ce)O 2 pellets were prepared from highly reactive precursors. Nanosized hydrated oxides were first obtained through precipitation route. Direct sintering was performed by heating between 1350°C and 1550°C. Microstructures composed of dense materials with submicrometric grains were achieved. a b s t r a c tThe preparation of dense U 1Àx Ce x O 2 mixed dioxides pellets was achieved from the initial precipitation of highly reactive precursors. In a first step, a wet chemistry route, based on the mixture of U 4+ and Ce 4+ in acidic solution with large excess of NH 4 OH, was set up to reach the precipitation of the cations. The solid phase was then dried under vacuum to avoid aggregation phenomena. Further characterization of the powders by XRD, EDS and TEM revealed the formation of hydrated U 1Àx Ce x O 2 ÁnH 2 O that probably resulted from the aging of hydroxide compounds. Also, microscopy investigations evidenced the nanosized character of the powder which was associated to high values of specific surface area, typically in the 100-150 m 2 g À1 range.The behavior of U 1Àx Ce x O 2 ÁnH 2 O versus temperature was investigated in a second part. If the increase of the heat temperature allowed one to observe an improvement of the crystallization state linked with the growth of crystallites, it was also accompanied by a strong decrease of the powders reactivity. On this basis, sintering tests were conducted in reducing atmosphere on the compounds as prepared. Dilatometry experiments indicated a low densification temperature compared to other ways of preparation reported in the literature. Also, the pellets prepared after firing at different temperatures (1350-1550°C) showed that a wide range of microstructures was achievable. Particularly, bulk materials with densities of 90-95% of the calculated value could be prepared with average grain size ranging from around 100 nm to more than 5 lm. This simple process of elaboration of dense materials from highly reactive hydrated oxide precursor thus appears as a very interesting way to prepare actinide oxides materials.

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“…Whitfield et al [19] have prepared two series of mixed oxides of (ThCe)O 2 and (ThCe)O 2Àx by hydrogen reduction in the temperature range of 973-1673 K. Thoria-ceria ceramic materials, in which ThO 2 powder was blended with (Th 0.87 Ce 0.13 )O 2 coprecipitated powder, have been produced to get the sintered pellets with the mean composition of (Th 0.94 Ce 0.06 )O 2 [20]. Crystallized thoria powder have been obtained also by heating various precursors such as thorium nitrate, oxalate or hydroxide at various temperatures ranging from 700°C up to 1600°C [21,22]. Hubert et al [7] have prepared ThO 2 powder by heat treatment of thorium oxalate and by precipitation of hydroxide to study the influence of the precursor and the calcination temperature on the dissolution of thorium dioxide.…”

Section: Introductionmentioning

confidence: 99%

Characterization of nanocrystalline (Th1−xCex)Oy powders synthesized by co-precipitation process

Yıldız

2007

Journal of Nuclear Materials

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Preparation of Thoria-Based Powders via Decomposition From Nitrate Solution

Cited by 3 publications

References 0 publications

Combining in situ HT-ESEM observations and dilatometry: An original and fast way to the sintering map of ThO2

Combining in situ HT-ESEM observations and dilatometry: An original and fast way to the sintering map of ThO2

An original precipitation route toward the preparation and the sintering of highly reactive uranium cerium dioxide powders

Characterization of nanocrystalline (Th1−xCex)Oy powders synthesized by co-precipitation process

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