Color is another optical property that enables ceramics to have multiple applications. When certain ions in precision ceramic processing materials contain easily excited electrons, light within the visible light range may be absorbed. At this point, the ceramic presents a color. This situation mainly occurs in transition elements with a single filled d-layer (such as v. Cr, Mn. Fe. Ni. Cu., or f-layer (rare earth elements)), which are relatively unstable. They have higher energy and require more energy, which can be excited with less energy. Therefore, they can selectively absorb visible light, such as C+ions, and slightly collect orange, yellow, and some green light, presenting a purple blue color; Ni2+absorbs other light through purple and red light, forming a purple gray color; Cu+ions absorb red, orange, yellow, and purple light, allowing blue and green to pass through: rare earth elements such as Ce have feather like absorption in the blue purple region, appearing yellow; Nd3+(neodymium) absorbs orange and yellow, presenting a reddish purple color.

Coloring of alumina ceramic processing

Al2O3 often requires coloring in practical applications, and industrial ceramic processing manufacturers can present different colors by introducing colored ionic compounds. For example, in semiconductor integrated circuits, aluminum oxide used as a packaging shell should have light shielding properties. Therefore, the Al2O3 on the back panel of the digital tube is also required to be black to ensure clear digital display. To achieve this, Fe2O3 and CoO can be added Cr2O3, TiO2, MnO, and other colored oxides are introduced into Al2O3. The black color of Al2O3 ceramics is due to the partial reduction of Ti+in the ceramic to Ti4+under the action of reducing atmosphere (H2) and high temperature. Ti3+can actually be seen as the T1+of bound electrons, i.e. Ti4+e -. This bound electron is a weakly bound electron and can be seen as the "color center" in titanium dioxide, so this type of ceramic appears black. Another commonly used red purple Al2O3 is the introduction of Cr2O3 and MnO into Al2O3 ceramics. Containing about 1% Cr2O3 and Al2O3, ceramics often appear red due to the solid solution α- The Cr3+ions in the Al2O3 lattice exhibit strong selective absorption of visible light's blue-green color, resulting in a complementary blue-green color, namely pink.