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Rutile is an oxide mineral composed of titanium dioxide (TiO 2), the most common natural form of TiO 2. Rarer polymorphs of TiO 2 are known, including anatase , akaogiite , and brookite . Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high ...
The majority of transition metal dioxides (MO 2) have the rutile structure, seen to the right. Materials of this stoichiometry exist for Ti, Cr, V and Mn in the first row transition metal and for Zr to Pd in the second. The rutile structure is generated by filling half of the octahedral sites with cations of the hcp oxygen anion array. [5] [6]
The rutile structure is widespread for other metal dioxides and difluorides, e.g. RuO 2 and ZnF 2. Molten titanium dioxide has a local structure in which each Ti is coordinated to, on average, about 5 oxygen atoms. [9] This is distinct from the crystalline forms in which Ti coordinates to 6 oxygen atoms. Structure of anatase.
For example, anatase is less hard (5.5–6 vs. 6–6.5 on the Mohs scale) and less dense (specific gravity about 3.9 vs. 4.2) than rutile. Anatase is also optically negative, whereas rutile is optically positive. Anatase has a more strongly adamantine or metallic-adamantine luster than that of rutile as well. [8]
2 Structure. 3 Physical properties. 4 See also. ... Download as PDF; Printable version; ... RhO 2 has the tetragonal rutile structure. [2]
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RuO 2 is extensively used for the coating of titanium anodes for the electrolytic production of chlorine and for the preparation of resistors or integrated circuits. [11] [12] Ruthenium oxide resistors can be used as sensitive thermometers in the temperature range .02 < T < 4 K.
It is in rutile crystal structure and coated with silica or/and alumina to prevent photocatalytic phenomena. The health risks of ultrafine TiO 2 from dermal exposure on intact skin are considered extremely low, [1] and it is considered safer than other substances used for ultraviolet protection. However titanium dioxide is a known carcinogen. [2]