Effects of Lithium Ion Irradiation on Yttria-Stabilized Zirconia Thin Films: Structural and Optical Investigations

Abstract

Thin films of yttria-stabilized zirconia (YSZ) were synthesized using spin coating technique on glass substrates with various concentration of yttria. The films were irradiated with Li³⁺ ions of energy 50 MeV and fluence values of 1 × 10¹¹, 5 × 10¹² and 5 × 10¹³ ions/cm². The results obtained for the irradiated films are compared with the pristine sample. X-ray diffraction (XRD) was employed to confirm the structural phase and investigate the variation in crystallinity of irradiated thin films. X-ray diffraction analysis confirmed that the higher yttria concentrations corresponded to decrease in crystallinity in the zirconia, corroborated by calculated crystallite sizes. Interestingly, no phase formation was observed in sample YSZ (8%), highlighting the necessity of elevated annealing temperatures for phase formation, particularly at higher yttria concentrations. Significantly, the structural information was validated through Raman spectroscopy which revealed the decrease in the monoclinic phase with increasing yttria doping. The optical band gap of Zirconia increased with higher yttria doping concentration, resulting in a range of band gap from 4.11 eV to 4.15 eV. The exposure of YSZ thin films to Li³⁺ ions with an energy of 50 MeV unveiled impacts of ion fluence. Lower fluence levels resulted in observable damage to crystallinity when contrasted with pristine YSZ samples, as manifested by the broadening of diffraction peaks. At moderate fluence levels, a decrease in crystallinity damage was noted, nonetheless, at higher fluence levels, the damage intensified once more. The ion irradiation of YSZ (8%) resulted in the emergence and growth of crystalline phases.