Neutron bombardment of boron carbide B 12 C 3 : A FT-IR, calorimetric (DSC) and ESR study.

Boron carbide B4C or, which is the same, B12C3, was neutron-bombarded at four different doses, namely at 1.09, 2.19, 3.28 and 4.38 × 1016n cm−2. The radiation-damage was studied by FT-IR, ESR (Electron Spin Resonance) and by DSC (Differential Scanning Calorimetry). It is shown that both FT-IR and ESR are useful techniques to monitor the radiation-damage level introduced in B12C3, with the ESR characterized by a higher sensitivity level than FT-IR. Thermal annealing of the neutron-treated B12C3from room temperature to 630°C permits to measure the release of the stored Wigner energy which was found comprised between 0.55 meV/atom at the lowest neutron dose to 2.29 meV/atom at the highest neutron dose employed. The values of Wigner energy measured on B12C3were comparable to those measured on fullerenes and graphite flakes at the same dose level. However, the thermal annealing of neutron-treated B12C3does not lead to the complete restoration of the pristine chemical structure before irradiation. [ABSTRACT FROM AUTHOR]