Neutron bombardment of boron carbide B₁₂C₃: A FT-IR, calorimetric (DSC) and ESR study

ABSTRACT

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 × 10¹⁶ 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°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.

KEYWORDS:

• boron carbide
• neutron bombardment
• FT-IR
• ESR
• DSC

Acknowledgments

We wish to thank Dr. Michele Prata from LENA, Laboratorio Energia Nucleare Applicata in Pavia, Italy, for the kind assistance in the neutron irradiation experiments.