High-Temperature Study of Multivalent Elements in Glass-Forming Melts: the Particular Case of Iron

摘要

Linear sweep voltammograms and absorption spectra were recorded in Na_2O·2.5 SiO_2 containing about 1 wt% Fe at some temperatures ranging from 600℃ to 1000℃. The reduction peaks which are observed in the melt at 600℃ disappear at 1000℃. The absorption spectra obtained at high temperature are characteristic by a displacement of the charge transfer band and of the band related to octahedral Fe(Ⅱ) towards higher wavelengths. No remarkable change in the Fe(Ⅲ)-Fe(Ⅱ) redox equilibrium and in the coordination of the Fe(Ⅱ) has been observed between 600℃ and 1000℃.