The fluorescence of Fe3+ in ordered and disordered phases of LiAl5O8

摘要: Abstract LiAl 5 O 8 has the inverse spinel structure. It exhibits a strong red fluorescence when lightly doped with Fe 3+ . Measurements were made of and excitation spectra in both ordered disordered phases :Fe. The phase its maximum at 680 nm, consists two components maxima 675 nm 730 nm. positions intensities these are temperature independent from 77°K to least 400°K. decay simple exponential decays τ = 6.20 msec 1.72 msec; longer time is associated shorter wavelength, more intense component. shifted toward wavelengths apparently only one much dependent intensity, nearly single decay, 3.40 300°K. There evidence presence 6 A 1 ( S)→ 2 T I) transition due No such seen phase. We can say reasonably certainty that ions situated sites tetrahedral symmetry (A sites). Spin resonance suggests phase, substantial numbers occupy octahedral sites. Although difference between observed consistent this suggestion, no clear conclusion be drawn regarding location Efforts obtain good theoretical agreement optical transitions energies calculated crystal field theory have not been successful.