Design, Synthesis, and Application of Colored Cobalt Pigments (Pink, Blue, Green)

AUTOR(ES)
FONTE

J. Braz. Chem. Soc.

DATA DE PUBLICAÇÃO

2020-11

RESUMO

The combination of white or colorless oxides (MgO, Al2O3, ZnO) with colorant ions (Co2+) generates colored pigments (pink, blue, green). The color is caused by the insertion of the colorant ion in the respective crystal lattices (periclase, alumina, wurtzite), as verified by X-ray diffraction. Absorption spectra in the visible region show analogous triplet behavior of the absorption bands for the doped alumina and wurtzite samples but a difference in tetrahedral distortion, which generates blue and green pigments. In contrast, cobalt-doped periclase has color-related parameters related to the pink color. Crystallite and particle sizes show nanometric dimensions in the range of 20-60 nm (magnesium), 20-180 nm (aluminum), and 40-220 nm (zinc). The color is related to the shape (crystalline phase), size, and presence of chromophore ions with absorption in the visible region. Colorimetric studies (CIE L*a*b*) show variations between colors as a function of the polysaccharide that is used (starch or pectin) as fuel. The color variation is subtle in some cases but is significantly noticeable in other cases. Commercial colorless ink dispersion (10% m/m) shows excellent compatibility with the maintenance of hues and a slight increase in color saturation (C*).

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