Iron oxide red, iron oxide black, iron oxide blue, iron oxide yellow, iron oxide brown, and iron oxide green are equivalent to iron oxide pigments. They are both oxides. Why do the colors appear different? This article will analyze the closest ones for you Why are the colors of the two pigments-iron oxide yellow and iron oxide green different?
The different molecular formulas lead to different colors of iron oxide yellow and iron oxide green
The molecular formula of iron oxide yellow is Fe2O3, and the crystals are mainly Fe3 and O2-; the molecular formula of iron oxide green is FeO, and the crystals are mainly Fe2 and O2-. Fe3 is yellow, and Fe2 is green. Obviously, the difference in molecular formula causes The color of the two is different.
Speaking of this, some people may wonder. Fe2 is green in solution. How about in crystals? Some literature says that the molecular formula of iron oxide green is a chemical formula with crystal water: Fe2O3?H2O, when used as an inorganic pigment Iron oxide red, iron oxide green, and iron oxide yellow are all in the form of crystals. Is their color mechanism different because of their crystal structure?
Actually, this possibility exists, and it has something to do with the ligands of Fe2 complexes. For example, hemoglobin is red. The crystal structure is generally considered to have reflection and refraction effects, but it does not seem to affect the wavelength of the photon. The complex changes the electron energy level interval of Fe2 and Fe3, and the energy of the photon released by the energy level transition is different. Because the color generally seen is that the electron is excited by light and then returns from the high energy level to the low energy level. The wavelength of the released photons is within the range of human vision, and colors can be seen.
