Preparation and characterization of Co_2TiO_4 and doped Co_(2-x)M_xTiO_4(M = Zn~(2+), Ni~(2+))-coated mica composite pigments

摘要

Green composite pearlescent pigments were prepared by coating Co_2TiO_4 and doped Co_(2-x)M_xTiO_4 nanoparticles on mica. The effects of calcination temperature, Ti/Co mole ratio and doped ions Ni~(2+) and Zn~(2+) on the crystal structure of mica/ Co_(2-x)M_xTiO_4 were studied. Scanning electron microscopy, atomic force microscopy and X-ray diffraction (XRD) technique were employed to characterize the morphology and crystal features of the composite particles. TG-DSC analysis and XRD patterns analysis showed that the appropriate calcination temperature for mica/Co_2TiO_4 pigments was about 1000 ℃. UV-Vis spectroscopy and CIE L~*a~*b~* parameters revealed that the composite pigments were yellow-green, and the color and colorimetric parameters changed with the particle size of mica, types of coated pigments and coating amount of pigments on mica. Moreover, the lightness L~* of mica/ Co_(2-x)M_xTiO_4 pigments was larger than that of undoped mica/Co_2TiO_4, and it increased with increasing doped Zn~(2+) and Ni~(2+) content.