Rutile Titanates

Rutile titanates represent by far the largest commercial class of CICPs. Chromium antimony titanate yellows (C.I. Pigment Brown 24) are the most widely used, followed by nickel antimony titanate yellows (C.I. Pigment Yellow 53). Manganese antimony titanate browns (C.I. Pigment Yellow 164) occupy a much smaller market share, and the other rutile grades a significantly smaller fraction still. 

It occurs in the minerals rutile, ilmenite, and sphene, and is present in titanates and in many iron ores. Titanium is present in the ash of coal, in plants, and in the human body. 

The main electroceramic apphcations of titanium dioxide derive from its high dielectric constant (see Table 6). Rutile itself can be used as a dielectric iu multilayer capacitors, but it is much more common to use Ti02 for the manufacture of alkaline-earth titanates, eg, by the cocalciuation of barium carbonate and anatase. The electrical properties of these dielectrics are extremely sensitive to the presence of small (<20 ppm) quantities of impurities, and high performance titanates require consistently pure (eg, >99.9%) Ti02- Typical products are made by the hydrolysis of high purity titanium tetrachloride. 

Titanium Dioxide (Titania, Titanium White, Rutile, Anatase, Brookite, Titanic Anhydride, Titanic Acid Anhydride, Titanic Oxide). Ti02, mw 79.90, Selected Parameters of the Allotropic Forms of Ti02... 

Finally, a number of other mixed oxides that do not have the perovskite structure have also been examined. For example, niobium titanates with the rutile structure,tetragonal tungsten bronze... 

Titanium was discovered in 1791 by William Gregor, an English clergyman and amateur chemist. He identified it in a black sand (now known to be ilmenite) sent to him for analysis from the Menacchan Valley in Cornwall. Four years later, the famous German chemist Klaproth rediscovered the element in the ore rutile, one form of titanium dioxide. He gave it the name titanium after the Titans who in Greek mythology were the sons of Earth. 

Nuclei are produced by converting the purified titanium oxide hydrate to sodium titanate, which is washed free of sulfate and then treated with hydrochloric acid to produce the rutile nuclei. Rutile nuclei can also be prepared by precipitation from titanium tetrachloride solutions with sodium hydroxide solution. 

Vemeuil (flame fusion) Crystal growth from the melt mby, sapphires, and stars spinel rutile strontium titanate... 

For the Vemeuil growth of rutile and strontium titanate it is necessary to maintain strongly oxidizing conditions to prevent excessive reduction of Ti4+ to Ti3+. This is achieved by adding a third outer tube carrying extra oxygen to the Vemeuil torch (Fig. 1) in the tricone modification. Annealing in 02 at about 1100°C is subsequently used to achieve full oxidation. 

Another circumstance is when deterioration becomes apparent under fields in excess of 0.5 MVm-1 at temperatures above 85 °C, and occurs more rapidly the higher the field or the temperature. The fall in resistance has been observed in single crystals of rutile and barium titanate and so must be assumed to be a bulk rather than a grain boundary effect, although there is evidence that grain boundaries play a part in degradation processes in ceramics. 

The resultant slag, a complex mixture of titanates, may contain 70—85% TiCL. The slag route is particularly useful when ilmenite is closely associated with haematite, from which it cannot economically be separated mechanically. Because the iron content of the slag is low, its use reduces the quantity of iron sulfate in the liquid effluent of sulfate process plants. Slag used as a feedstock for TiCl4 production must be low in magnesium and calcium. A variety of other ilmenite beneficiation or synthetic rutile processes have been pursued, primarily to provide alternative chloride process feedstocks. Low grade ilmenite... 

Zinc orthotitanate [12036-69-0], ZmTi04, a white solid having a density of 512(0) and a spinel structure, is obtained by heating the calculated amounts of the two oxides at 1000°C. Zinc orthotitanate forms a series of solid solutions with titanium dioxide, extending to the composition Zn2Ti04 1.5Ti02. These solid solutions begin to dissociate at 775°C with the formation of the rutile form of titanium dioxide. The properties of the rare-earth titanates and their electronic structure are available (117—119). 

Of these, bastnasite is the only mineral worked primarily for rare earths and both monazite and xenotime are mostly by-products of mining ilmenite, rutile, cassiterite, zircon or gold. Apatite and some multi oxide minerals like pyrochlore, euxenite, brannerite and loparite (a niobium titanate) are also commercial sources of rare earths, but production of RE from these is limited. 

Fig. 6.14 shows X-ray diffraction patterns of the products obtained after activation of the mixtures of Ba02 with rutile, anatase and metatitanium acid. It follows, that mechanochemical synthesis of barium titanate occurs only if anatase and metatitanium acid are used as initial reagents. The presence of barium carbonate phase was observed for all the products. For the mixture with anatase, the amount of barium carbonate increases with activation time, and for the mixture with metatitanium acid it... 

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