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@PHDTHESIS{Barrier:50675,
author = {Barrier, Diane Catherine},
title = {{C}haracterisation and fabrication of zirconia and thoria
based ceramics for nuclear applications},
volume = {4188},
issn = {0944-2952},
school = {Techn. Hochsch. Aachen},
type = {Dr. (FH)},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {PreJuSER-50675, Juel-4188},
series = {Berichte des Forschungszentrums Jülich},
pages = {165 p.},
year = {2005},
note = {Record converted from VDB: 12.11.2012; Aachen, Techn.
Hochsch., Diss., 2005},
abstract = {The reduction of the long term radiotoxicity of nuclear
waste during disposal is the aim of the research called
“Partitioning $\&$ Transmutation of minor actinides
(MAs)”, which also requires the development of inert
ceramic support materials. Moreover, after separation, if
the transmutation is not available, the actinides can be
conditioned into stable dedicated solid matrices
(Partitioning $\&$ Conditioning strategy).
Yttrium-stabilized zirconia and thoria are discussed in the
international nuclear community as candidates for the
fixation of long-lived actinides as target material for
transmutation and as stable materials for long-term final
disposal. The aims of the following work are twofold:
determine the impact of the addition of actinides, simulated
by cerium on the properties of the matrices and study the
possibility of synthesising homogeneous ceramics using
simple fabrication routes. Within this framework,
(Zr,Y)O$_{2-x}$ - CeO$_{2}$ and ThO$_{2}$ - CeO$_{2}$
powders with variable ceria contents (from 0 to 100 \%) were
synthesised by a co-precipitation method of nitrate
solution. The influence of ceria concentration on the
powder' properties, such as thermal behaviour and the
evolution of material crystallisation during annealing, was
investigated in detail by thermogravimetry (TG) coupled with
differential scanning calorimetry (DSC) and X-ray
diffraction (XRD). Both systems crystallise at high
temperature in a stable solid solution, fcc, fluorite type
structure and follow the Vegard’s law for the complete
range of ceria. For both systems a critical concentration of
20 mol \% has been established. For ceria concentrations
lower than 20 \%, the properties of the system are mainly
controlled by the matrix. Pellets with different ceria
concentrations were compacted from these powders by using
different technological cycles. In order to obtain materials
with reliable properties, the technological parameters of
each chosen fabrication route, have been optimised. By
employing mild wet methods (calcination at 600°C,
wet-grinding in acetone and fractionation in acetone),
(Zr,Y,Ce)O$_{2-x}$ pellets with densities of up to 0.97 TD
can be obtained. In the case of the (Th,Ce)O$_{2}$ system,
pressing by repressing from non-milled powder was selected
as the fabrication route, allowing the fabrication of
pellets with densities of up to 0.98 TD. In both cases,
materials with homogeneous repartition of pores, well formed
grains and boundaries and good mechanical properties were
obtained.},
cin = {ISR},
cid = {I:(DE-Juel1)VDB182},
pnm = {Nukleare Sicherheitsforschung},
pid = {G:(DE-Juel1)FUEK249},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/50675},
}