Titanium dioxide compounds

The CO2 adsorption and the concurrent reaction with the electrons highly depends on the nature of the material surfaces. Not all the semiconductors have the similar surface arrangement, therefore, the reaction pathway and the interaction of CO2 moiety with surfaces varies according to the materials used. The product and yield vary within the titanium dioxide compounds itself [124]. Since the CO2 reduction doesn t only depend on the visible light activity of the photocatalytic material, but also many other fac-... 

Titanium IV) oxide, T1O2. See titanium dioxide. Dissolves in concentrated alkali hydroxides to give titanates. Mixed metal oxides, many of commercial importance, are formed by TiOj. CaTiOj is perovskite. BaTiOa, per-ovskite related structure, is piezoelectric and is used in transducers in ultrasonic apparatus and gramophone pickups and also as a polishing compound. Other mixed oxides have the il-menite structure (e.g. FeTiOj) and the spinel structure (e.g. MgjTiO ). 

ANTIBIOTICS - NUCLEOSIDES AND NUCLEOTIDES] (Vol 3) -titanium dioxide in [TITANIUM COMPOUNDS - INORGANIC] (Vol24)... 

Fillers. These are used to reduce cost in flexible PVC compounds. It is also possible to improve specific properties such as insulation resistance, yellowing in sunlight, scuff resistance, and heat deformation with the use of fillers (qv). Typical filler types used in PVC are calcium carbonate, clays, siHca, titanium dioxide, and carbon black. 

A significant advantage of the PLM is in the differentiation and recognition of various forms of the same chemical substance polymorphic forms, eg, brookite, mtile, and anatase, three forms of titanium dioxide calcite, aragonite and vaterite, all forms of calcium carbonate Eorms I, II, III, and IV of HMX (a high explosive), etc. This is an important appHcation because most elements and compounds possess different crystal forms with very different physical properties. PLM is the only instmment mandated by the U.S. Environmental Protection Agency (EPA) for the detection and identification of the six forms of asbestos (qv) and other fibers in bulk samples. 

U.S. production of titanium dioxide in 1993 was 1.16 x 10 t, an increase of about 2.2% over 1992 (15). The annual production increased on an average of 5.4% in the 1980s (16). There are approximately 50 world producers of titanium dioxide pigments. The world s leading suppHers are Du Pont (- 24% worldwide share), Tioxide (the U.K. Co. owned by ICI), and SCM Corp. Other producers include Kerr McGee, Tiwest, Kemira Oy, Kronos, and Bayer AG (see Titanium compounds, inorganic). 

Putile Ceramic Pigments. StmcturaHy, aH mtile pigments are derived from the most stable titanium dioxide stmcture, ie, mtile. The crystal stmcture of mtile is very common for AX2-type compounds such as the oxides of four valent metals, eg, Ti, V, Nb, Mo, W, Mn, Ru, Ge, Sn, Pb, and Te as weH as haHdes of divalent elements, eg, fluorides of Mg, Mn, Fe, Co, Ni, and Zn. 

Chemical pigments or synthetics may be metal compounds. A good example is white titanium dioxide. Other chemical pigments include cadmium sulfide colors, iron blue, and several synthetic versions of iron oxides. 

Paints. Paints account for perhaps 3% of sulfur consumption (see Paint). The main sulfur use is for the production of titanium dioxide pigment by the sulfate process. Sulfuric acid reacts with ilmenite or titanium slag and the sulfur remains as a ferrous sulfate waste product. Difficulties with this process have led to the development of the chloride process (see Pigments, inorganic Titanium compounds). 

Precipitation of a hydrated titanium oxide by mixing aqueous solutions of titanium chloride with alkaU forms the precipitation seeds, which are used to initiate precipitation in the Mecklenburg (50) variant of the sulfate process for the production of pigmentary titanium dioxide. Hydrolysis of aqueous solutions of titanium chloride is also used for the preparation of high purity (>99.999%) titanium dioxide for electroceramic appHcations (see Ceramics). In addition, hydrated titanium dioxide is used as a pure starting material for the manufacture of other titanium compounds. 

Titanium Trifluoride. The trifluoride (121) is a blue crystalline soHd, density 2980 kg/m, ia which the titanium atoms are six-coordinate at the center of a slightly distorted octahedron, where the mean Ti—F distance is 197 pm. Titanium trifluoride [13470-08-1] is stable ia air at room temperature but decomposes to titanium dioxide when heated to 100°C. It is insoluble ia water, dilute acid, and alkaUes but decomposes ia hot concentrated acids. The compound sublimes under vacuum at ca 900°C but disproportionates to titanium and titanium tetrafluoride [7783-63-3] at higher temperatures. 

The formulation of calcium chelate materials is based upon the formation of a low-solubiUty chelate between calcium hydroxide and a sahcylate. Dycal utilizes the reaction product of a polyhydric compound and sahcyhc acid. Other sahcyhc acid esters can be similarly used. Vehicles used to carry the calcium hydroxide, extenders, and fillers may include mineral oil, A/-ethyl- -toluenesulfonamide [80-39-7] and polymeric fluids. The filler additions may include titanium dioxide [13463-67-7] zinc oxide, sihca [7631-86-9], calcium sulfate, and barium sulfate [7727-43-7]. Zinc oxide and barium sulfate are useflil as x-ray opacifying agents to ensure a density greater than that of normal tooth stmcture. Resins, rosin, limed rosins, and modified rosins may serve as modifiers of the physical characteristics in both the unset and set states. 

Mineral fillers are used for light-colored compounds. Talc has a small particle size and is a semireinforcing filler. It reduces air permeabihty and has htde effect on cure systems. Calcined clay is used for halobutyl stoppers in pharmaceutical appHcations. Nonreinforcing fillers, such as calcium carbonate and titanium dioxide, have large particle sizes and are added to reduce cost and viscosity. Hydrated siUcas give dry, stiff compounds, and their acidity reduces cure rate hence, their content should be minimized. 

The role of antimony oxide is not entirely understood. On its own it is a rather weak fire retardant although it appears to function by all of the mechanisms listed above. It is, however, synergistic with phosphorus and halogen compounds and consequently widely used. Other oxides are sometimes used as alternatives or partial replacements for antimony oxide. These include titanium dioxide, zinc oxide and molybdenic oxide. Zinc borate has also been used. 

---