Positron Nondestructive Testing of Gamma-Neutron Irradiated Boron Nitride Ceramics
| Autor: | A. D. Buravov, V. A. Kotenev, A. Yu. Tsivadze, V. V. Vysotskii, A. V. Gol’danskii, I. I. Bardyshev |
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| Rok vydání: | 2019 |
| Předmět: |
Nuclear reaction
Materials science Astrophysics::High Energy Astrophysical Phenomena 020209 energy Physics::Medical Physics Organic Chemistry Metals and Alloys 02 engineering and technology Alpha particle Radiation 021001 nanoscience & nanotechnology Surfaces Coatings and Films Positron annihilation spectroscopy Ionizing radiation Condensed Matter::Materials Science Vacancy defect 0202 electrical engineering electronic engineering information engineering Materials Chemistry Neutron Irradiation Atomic physics 0210 nano-technology |
| Zdroj: | Protection of Metals and Physical Chemistry of Surfaces. 55:1015-1018 |
| ISSN: | 2070-206X 2070-2051 |
| Popis: | The effect of pulse neutron gamma-radiation on material made from sintered ceramics of hexagonal boron nitride α-BN is studied using positron annihilation spectroscopy (PAS). The radiation vacancy defects of the α-BN crystal lattice are effective traps of the positrons diffusing into the bulk particles of the material. The positrons’ lifetime (LT) spectra and angular correlation curves of annihilation gamma-ray quanta (ACAR) in ceramic specimens irradiated by neutrons with a cumulative dose of the neutron flow of 1013 to 1014 neutron/cm2 (the average energy of the neutrons is 1.7 MeV) and gamma radiation of 103 to 105 Р (Eγ = 1 MeV) with the subsequent annealing of the irradiated specimens at 600°C are measured. The observed changes of the annihilation characteristics of the LT and ACAR in the irradiated and sintered specimens allow us to conclude that there is an effective capture of the alpha particles formed upon neutron irradiation via the nuclear reaction B10(n, α)Li7 with vacancy defects. Helium atoms are released from vacancies to the surface of the α-BN plates upon annealing of the irradiated specimens at 600°C. This mechanism explains the high level of radiation stability of α-BN ceramic dielectrics in ionizing radiation fields. |
| Databáze: | OpenAIRE |
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