Structural, optical and hydrophobic properties of single-crystal muscovite mica implanted with 500 keV Au+1 ions

Abstract

This study investigates the impact of 500 keV singly charged gold ion (Au⁺¹) implantation in single-crystal muscovite mica, a material widely recognized for its diverse technological applications, particularly in radiation physics. By maintaining a constant incident ion energy of 500 keV, the study examines the effects of ion dose (ranging from 10¹² to 10¹⁵ ions/cm²) on the structural, optical, and hydrophobic properties of mica. The projected range of Au⁺¹ ions, reaching a depth of 120 nm, induces various defects, including displacement damage, vacancies, and dislocations. XRD analysis reveals a decrease in peak intensity, an increase in FWHM, increase in microstrain and a reduction in average crystallite size with increasing ion dose, indicating a progressive loss of crystallinity. Additionally, a symmetric lattice plane shift toward lower angles is observed in all lattice planes, signifying the presence of tensile stresses. This shift results in the expansion of the unit cell and an increase in d-spacing due to ion-induced defects. The expansion of the unit cell volume exhibits a linear increase up to an ion dose of 10¹³ ions/cm², after which it saturates. This trend is determined by estimating lattice parameters from the Rietveld-refined XRD patterns of samples implanted with varying ion doses. Williamson-Hall analysis further reveals a correlation between crystallite size and strain, showing a significant reduction in crystallite size accompanied by an increase in microstrain as the ion dose increases. UV–visible spectrophotometry measurements indicate a decrease in the optical band gap and an increase in Urbach energy with increasing ion dose, attributed to ion-implantation-induced structural transformations. Additionally, an increase in the surface contact angle is observed, suggesting changes in the physicochemical properties of mica and a notable shift toward a more hydrophobic surface. These findings provide valuable insights into the interaction between gold ion beams and mica surfaces, reinforcing its potential use as a radiation-facing material.