2020/02/14 by R. Mittal, Ranjan Mittal, Mayanak K. Gupta +18 · 8 citations
Chemistry · Engineering · Materials Science · Physics and Astronomy · #Ab initio #Advancements in Battery Materials #Annihilation #Atomic physics #Chemical physics #Chemistry #Composite material #Graphene #Graphene research and applications #Graphite #Graphite, nuclear technology, radiation studies #Irradiation #Materials science #Nanotechnology #Neutron #Neutron cross section #Neutron moderator #Neutron temperature #Nuclear graphite #Nuclear physics #Organic chemistry #Physics #Topology (electrical circuits) #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.102.064103
published in Physical review. B./Physical review. B 102(6) (American Physical Society) · 23 Pages, 6 Figures, Supplementary Materials
arxiv created 2020/02/14 · openalex created_date 2020/02/24 · openalex publication_date 2020/08/06 · arxiv updated 2020/08/12 · openalex updated_date 2026/08/05
Graphite has been used as a neutron moderator or reflector in many nuclear reactors. The irradiation of graphite in a nuclear reactor results in a complex population of defects. Heating of the irradiated graphite at high temperatures results in annihilation of the defects with release of an unusually large energy, called the Wigner energy. From various experiments on highly irradiated graphite samples from the CIRUS reactor at Trombay and ab initio simulations, we have identified various 2-, 3-, and 4-coordinated topological structures in defected graphite, and provided a microscopic mechanism of defect annihilation on heating and release of the Wigner energy. The annihilation process involves cascading cooperative movement of atoms in multiple steps involving an intermediate structure. Our work provides insights in understanding of the defect topologies and annihilation in graphite which is of considerable importance to wider areas of graphitic materials including graphene and carbon nanotubes.