Fluoride phosphate glasses are attractive candidates for high-performa
nce glass for the deep ultraviolet range. The calculated values for th
e ultraviolet resonance wavelengths are comparable with those of CaF2,
BeF2 and SiO2. However, the experimental ultraviolet transmission of
glass is frequently limited by extrinsic absorption due to trace impur
ities, mainly transition metals. The influence of the redox states of
Fe, Cu, Pb and Ni in the ppm range on the ultraviolet absorption was i
nvestigated. The individual absorption coefficients per ppm ion and th
e redox equilibria resulting from the melting conditions and refining
temperature were determined. Fe3+, CU2+ and pb(2+) have the largest in
fluence on the ultraviolet absorption. Glasses melted under reducing c
onditions have much higher ultraviolet transmission at 250 nm than gla
sses melted under oxidizing conditions. The ultraviolet absorption of
the glass is strongly dependent on the reducing temperature. The ultra
violet absorption decreases and the luminescence increases drastically
with increasing reducing temperature from 850 to 1100 degrees C. The
redox equilibria are shifted to Fe2+ and Cu+, over 1100 degrees C towa
rds Cu-0 colloids too. The molar absorption coefficients in the ultrav
iolet range of the lower redox states are more than one order lower th
an those of the higher redox states.