Effects of swift heavy ions irradiation parameters on optical properties of muscovite mica

TL;DR

This study investigates how swift heavy ion irradiation affects the optical properties of muscovite mica, revealing that increased irradiation parameters lead to bond destruction, surface cleaving, and changes in band gap and defect levels.

Contribution

It provides new insights into the relationship between irradiation parameters and optical property modifications in muscovite mica.

Findings

Band gap narrows with increased irradiation.

Urbach energy increases with higher fluences and energy loss.

Surface becomes smoother and bonds are destroyed at higher irradiation levels.

Abstract

Muscovite mica sheets with a thickness of 25 {\mu}m were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL. The fluences ranged from 1$\times$10^{10} ions/cm^2 to 8$\times$10^{11} ions/cm^2. The electronic energy loss (dE/dx)_e was increased from 14.7 keV/nm to 31.2 keV/nm. The band gap and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet- visible spectroscopy. Periodic fringes in long wave length of the absorption spectra caused by interference phenomenon, were disturbed as the (dE/dx)_e increased. It was suggested that the chemical bonds between Tetrahedral-Octohedral-Tetrahedral (TOT) layers of mica were destroyed. Thus the smooth surface was cleaved after irradiation. The band gap was narrowed down with the increasing (dE/dx)_e and fluences. The values of Urbach energy were increased as the (dE/dx)_e and fluences gradually increased. It was indicated that the amount of defects and the proportion of amorphous structure were increased in mica irradiated under increased (dE/dx)_e and fluences. Fluences took a distinctly important role in optical properties of mica.