title: Redox response of actinide materials to highly ionizing radiation.
abstract: Energetic radiation can cause dramatic changes in the physical and chemical properties of actinide materials, degrading their performance in fission-based energy systems. As advanced nuclear fuels and wasteforms are developed, fundamental understanding of the processes controlling radiation damage accumulation is necessary. Here we report oxidation state reduction of actinide and analogue elements caused by high-energy, heavy ion irradiation and demonstrate coupling of this redox behaviour with structural modifications. ThO2, in which thorium is stable only in a tetravalent state, exhibits damage accumulation processes distinct from those of multivalent cation compounds CeO2 (Ce(3+) and Ce(4+)) and UO3 (U(4+), U(5+) and U(6+)). The radiation tolerance of these materials depends on the efficiency of this redox reaction, such that damage can be inhibited by altering grain size and cation valence variability. Thus, the redox behaviour of actinide materials is important for the design of nuclear fuels and the prediction of their performance.
authors.affiliation: Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Cameron L
authors.initials: CL
authors.lastname: Tracy
authors.affiliation: Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Maik
authors.initials: M
authors.lastname: Lang
authors.affiliation: Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Pray
authors.affiliation: Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Fuxiang
authors.initials: F
authors.lastname: Zhang
authors.affiliation: High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Popov
authors.affiliation: High Pressure Collaborative Access Team (HPCAT), Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
authors.forename: Changyong
authors.initials: C
authors.lastname: Park
authors.affiliation: 1] GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany [2] Technische Universität Darmstadt, 64287 Darmstadt, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Trautmann
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Bender
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Severin
authors.affiliation: Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna, Russia.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Skuratov
authors.affiliation: Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305, USA.
authors.forename: Rodney C
authors.initials: RC
authors.lastname: Ewing