Neutron bombardment of boron carbide B12C3: 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 x 10(16) n 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 B12C3 from room temperature to 630 degrees 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 B12C3 were comparable to those measured on fullerenes and graphite flakes at the same dose level. However, the thermal annealing of neutron-treated B12C3 does not lead to the complete restoration of the pristine chemical structure before irradiation.