RESUMO
Optical absorption measurements on a number of soda-lime-silica glasses of the base composition SiO[2] 72.6%, Na[2]O 15.92%, K[2]O 0.46%, CaO 10.04%, MgO 0.52%, A1[2]O[3] 0.41%, Fe[3]O[3] 0.02% [wt.%] containing varying amounts of nickel, cobalt, chromium, or copper oxide were carried out. The study is made in order to throw some light on the color state and the structure of these glasses. Experimental results indicate the observation of characteristic absorption bands for each transition metal ion. Nickel and cobalt ions as divalent are observed to exist in two coordination states, octahedral and tetrahedral. Chromium ions are found as trivalent and hexavalent states, while copper ions are predominantly existed in the divalent state. The results are interpreted in relation to the ligand field theory