OXIDATION-STATES OF TRANSITION-METALS IN ZBLAN

ZBLAN glasses doped with the transition metals Fe, Cu, Cr, Co, V and A g have been prepared under inert and oxidizing conditions (N2 and NF3) . The optical absorption spectra of the transition metals in the glass es have been measured by UV-VIS-NIR spectroscopy. The transition metal s existed in various oxidation states, depending on the melting atmosp here and processing time. Different starting valencies of the dopants were used to check that equilibrium was obtained. The results are comp ared with the corresponding redox equilibria in oxide glasses and prev ious studies in fluoride glasses.