Thermodynamics kinetics of boron carbide under gamma irradiation dose
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Date
2019
Authors
Mirzayev, Matlab
Demir, Ertugrul
Mammadov, Khagani
Mehdiyeva, Ravan
Jabarov, Sakin
Tugrul, A. Beril
Biira, Saphina
Tiep, Nguyen
Thabethe, Thabsile
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of Modern Physics B
Abstract
In this paper, high purity boron carbide samples were irradiated by 60Co gamma radioisotope source (0.27 Gy/s dose rate) with 50, 100, 150 and 200 irradiation hours at
room-temperature. The unirradiated and irradiated boron carbide samples were heated
from 30 C to 1000 C at a heating rate of 5 C/min under the argon gas atmosphere of
ow rate 20 ml/min. Thermogravimetric (TG) and Differential Scanning Calorimetry
(DSC) were carried out in order to understand the thermodynamic kinetics of boron carbide samples. The weight kinetics, activation energy and specific heat capacity of
the unirradiated and irradiated boron carbide samples were examined in two parts,
T 650 C and T 650 C, according to the temperature. The dynamic of quantitative
changes in both ranges is different depending on the irradiation time. While the phase
transition of unirradiated boron carbide samples occurs at 902 C, this value shifts upto
940 C in irradiated samples depending on the irradiation time. The activation energy
of the unirradiated boron carbide samples decreased from 214 to 46 J/mol in the result
of 200 h gamma irradiation. The reduction of the activation energy after the irradiation
compared to the initial state shows that the dielectric properties of the irradiated boron
carbide samples have been improved. After the gamma irradiation, two energy barrier
states depending on the absorption dose of samples were formed in the irradiated samples. The rest and second energy barriers occurred in 0.56{0.80 and 0.23{0.36 eV energy
intervals, respectively. The existence of two energy levels in the irradiated boron carbide
indicates that the point defects are at deep levels, close to the valence band.
Description
Keywords
Boron carbide, Gamma irradiation, Thermodynamics kinetics, Heat ow rate, Activation energy
Citation
Mirzayev, M., Demir, E., Mammadov, K., Mehdiyeva, R., Jabarov, S., Tugrul, A. B., ... & Thabethe, T. (2019). Thermodynamics kinetics of boron carbide under gamma irradiation dose. International Journal of Modern Physics B, 33(09), 1950073. DOI: 10.1142/S0217979219500735