Effect of the states of chromium ion on the colour characteristics of doped β-C₂S

The state of chromium ions in β-C₂S was studied according to crystalfield theory by optical spectroscopy and electron paramagnetic resonance. The energy levels of chromium ions were calculated. These ions exist in the form of Cr⁴⁺ and Cr⁵⁺, co-ordinated in distorted octahedra. The coloured β-C₂S hydrate fades because the level of tight absorption decreases due to the valence change of chromium ions as chromium is leaked.