Can We Describe phase Transition in Insulators within the Landau PT theory Framework?
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1215-V02-01
Can We Describe phase Transition in Insulators within the Landau PT theory Framework? David Simeone1, Gianguido Baldinozzi2, Dominique Gosset1, Laurence Luneville3, and Leo Mazerolles4 1
CEA/DEN/DMN/SRMA/LA2M, Matériaux Fonctionnels pour l’Energie, Equipe Mixte CEACNRS-ECP, CEN Saclay, Gif sur Yvette, 91191, France. 2 CNRS, Matériaux Fonctionnels pour l’Energie, CNRS-CEA-ECP, Laboratoire SPMS, Ecole Centrale de Paris, Chatenay Malabry, 92292, France. 3 CEA/DEN/DM2S/SERMA/LLPR, Matériaux Fonctionnels pour l’Energie, Equipe Mixte CEACNRS-ECP, CEN Saclay, Gif sur Yvette, 91191, France. 4 CNRS, Institut des Sciences Chimiques Seine Amont, Thiais, 92000, France ABSTRACT Based on studies of simple oxides, this paper demonstrates that the specific energy deposition modes under irradiation induce modifications of materials over different length scales. On the other hand, we show the Landau phase transition theory, widely used to explain the structural stability of materials out of irradiation, can give a general framework to describe the behavior of these oxides under irradiation. The use of X-ray diffraction techniques coupled with the Raman spectroscopy allows defining in a quantitative way the phenomenological parameters leading to predictive results. This paper clearly shows that in two model systems, pure zirconia and spinels, no unexpected new phases are produced in these oxides irradiated at room temperature and with different fluxes. Such a phenomenological approach may be useful to study the radiation tolerance of many crystalline ceramics (e.g. the zirconium based americium ceramics).
INTRODUCTION A significant growth in the utilization of nuclear power is expected to occur over the next several decades due to increasing demand for energy and environmental concerns related to emissions from fossil fuel plants. This has focused increasing attention on issues related to the permanent disposal of nuclear waste and the improvement of nuclear plants technologies. The achievement of such a goal requires continued improvements in safety and efficiency particularly related to the performance of materials [1]. The related research challenges represent some of the most demanding tests of our fundamental understanding of materials science and chemistry, and they provide significant opportunities for advancing basic science with broad impacts in the material science community. The fundamental challenge is to understand and control chemical and physical phenomena in multi-component systems from femto-seconds to millennia, at temperatures up to 1000ºC, and for radiation doses up to hundreds of displacements per atom (dpa). New understanding is required for the microstructural evolution of the materials. Their phase stability under irradiation is an active field of debate.
In this context, ceramics appear to be incontrovertible materials. Crystalline oxide waste forms such as zircon [2] or spinel [3] have been proposed to accommodate a limited range of active species such as plutonium and multiphase systems such
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