3 сентября, 2015 
Pokraskin Titanate spinels form a much smaller class of pigments than the rutiles. The M3O4 stoichiometry of spinel is met by reacting two units of +2 metal oxide with one unit of TiO2, according to Eq. (5-1).
2MO + TiO2 ^ M2TiO4 spinel (5-1)
M = Ni(II), Co(II), Zn(II), Fe(II)
Titanates are inverse spinels, where a number of the +2 ions occupy octahedral coordination sites in the lattice. Commercially important grades are the cobalt tita — nate greens and iron titanate browns.
Cobalt titanate greens are generally modified by Zn(II) and Ni(II) oxides to produce their bright green colors. The greens can be in the same color space as chro — mium(III) oxide green, and compete somewhat since they have similar durability characteristics. However, cobalt titanate greens are usually formulated to give brighter and cleaner colors shades, some with bluer hues that are not otherwise available. Primarily as a result of the cobalt they contain, cobalt titanate greens are more expensive by comparison.
Iron titanates are formed from combinations of iron(II) oxide and TiO2. These formulations are commonly modified by additions of iron(III) oxide, zinc(II) oxide, and aluminum(III) oxide. Like the cobalt titanates, these are inverse
spinels structures. Iron titanate pigments yield light yellow-brown to dark reddish-brown hues. In many cases these pigments exhibit greater heat stability than zinc ferrite or iron oxide browns, and are generally used in applications for this purpose.
5.4.3
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