The effect of electron irradiation on the structure and properties of α-Fe2O3 nanoparticles as cathode material

Abstract

The work is devoted to the study of the effect of electron irradiation on the ordering of the crystal structure and properties of Fe oxide nanoparticles obtained by chemical synthesis and subsequent thermal annealing. X-ray diffractometry, scanning electron microscopy, energy dispersive analysis and 57Fe Mössbauer spectroscopy were used as research methods. It was found that increasing the irradiation dose from 50 to 150 kGy leads to enlargement of particles from initial size 40 nm to 45–50 nm, while subsequent irradiation leads to the formation of ellipsoidal or rhombic particles, the average size of which is no more than 50–60 nm. Using the method of Mössbauer spectroscopy, it was found that with an increase in the irradiation dose, the relative intensity of the subspectrum of 57Fe nuclei in locally heterogeneous areas decreases from 9.7 ± 0.8% to 0.6 ± 0.6%, which indicates a significant decrease in the density of oxygen vacancies and the ordering of the crystal and magnetic structure nanoparticles. A decrease in the density of oxygen vacancies and a decrease in deformation distortions in the structure indicate the promise of using electronic irradiation to modify the properties of nanoparticles. In the course of life tests of the applicability of the studied nanoparticles as cathode materials for lithium-ion batteries, it was found that increasing the irradiation dose leads to an increase in the specific capacitance from 202 to 215–218 mA g−1, as well as a decrease in capacitance loss in case of a change in the charge/discharge rate, which indicates an increase in the stability of nanoparticles to degradation arising in the process of life tests.