the crystallization effect on the optical properties of oxyfluoride glass-ceramics containing caf2 nanocrystals doped with y3+ ions

In the present study, the oxyfluoride glasses of sio2-al2o3-caf2 system containing different amounts of y3+ ions were prepared through the convenient melting method. the crystallization temperatures and size of the caf2 nanocrystals were obtained from dta curves and xrd patterns, respectively. as a consequence, the optimum amount of y2o3 dopant (0.5wt%) and the suitable composition for basic glass were determined from the viewpoints of better crystallization behavior and higher transparency. the ftir spectra approved the presence of oxyfluoride glass-ceramic structure in samples. the optical parameters (fermi energy level, urbach energy, direct and indirect band gaps) were calculated using uv-vis spectra. the decreasing trend of fermi energy level for glass-ceramic samples crystallized at higher temperatures is related to better semiconducting behavior. urbach energy and optical band gap of the glass-ceramic samples were reduced due to the increment of the structural order and the emergence of dangling bonds, respectively.