the
conduction band is formed by Ce4f and Mn3d/Si3p resulting in
the band gap widening (2.78/2.90 eV). As far as the effect of
counter ions is concerned, Si co-doped pigments give
practically the same spectra, with a blue shift in the absorption
edge resulting in bright reddish brown hue. A gradual shift of
CT band can be actually appreciated along with the increase in