A systematic investigation of the phase assemblage and microstructure of the zirconolite CaZr1-xCexTi2O7 system

Abstract

A series of zirconolite ceramics with nominal stoichiometry CaZr1-xCexTi2O7 (0.0 ≤ x ≤ 0.4) were synthesised under oxidizing, inert and reducing conditions, by a conventional solid-state cold press and sinter method. The evolution of phase assemblage and microstructure were characterized by XRD, SEM-EDS, Ce-L3 XANES and Raman spectroscopy techniques. It was determined that the relative yield of zirconolite-2M and zirconolite-4M polytypes, alongside secondary perovskite phases, was influenced by processing environment via the control of Ce3+/4+ speciation. Oxidizing conditions produced a mixture of zirconolite-2M and zirconolite-4M polytypes due to the formation of Ce4+. Inert and reducing conditions yielded predominantly zirconolite-2M and a Ce-bearing perovskite phase through favouring Ce3+ speciation.

Metadata

Authors/Creators:

Blackburn, L.R. https://orcid.org/0000-0002-5889-2035
Sun, S.
Gardner, L.J. https://orcid.org/0000-0003-3126-2583
Maddrell, E.R.
Stennett, M.C. https://orcid.org/0000-0002-8363-9103
Hyatt, N.C.

Keywords:

Cerium; Plutonium; Zirconolite; Immobilisation; Surrogate; Wasteform; Ceramic

Dates:

Accepted: 20 March 2020
Published (online): 7 April 2020
Published: 1 July 2020

Institution:

The University of Sheffield

Academic Units:

The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Materials Science and Engineering (Sheffield)

Funding Information:

Funder	Grant number
ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL	EP/N017870/1
NUCLEAR DECOMMISSIONING AUTHORITY	UNSPECIFIED
ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL (EPSRC)	UNSPECIFIED

Depositing User:

Symplectic Sheffield

Date Deposited:

20 May 2020 11:16

Last Modified:

20 May 2020 11:16

Status:

Published

Publisher:

Elsevier BV

Refereed:

Yes