Oxide refractive indices

The hybrid films had a film thickness ranging from 1.53 to 2.61 //m, as shown in Table 1. The refractive index of the hybrid film at 1319 nm decreases with increasing the silica content since the refractive index of silica segment is lower than that of PMMA. However, it is higher than that of thermal oxide (refractive index = 1.458) and thus core>cladding waveguide structure can be formed in the prepared optical planar waveguides. The optical properties of the hybrid films are shown in Table 1. 

Methylene iodide [75-11-6], CH2I2, also known as diio dome thane, mol wt 267.87, 94.76% I, mp 6.0°C, and bp 181°C, is a very heavy colorless Hquid. It has a density of 3.325 g/mL at 20°C and a refractive index of 1.7538 at 4°C. It darkens in contact with air, moisture, and light. Its solubiHty in water is 1.42 g/100 g H2O at 20°C it is soluble in alcohol, chloroform, ben2ene, and ether. Methylene iodide is prepared by reaction of sodium arsenite and iodoform with sodium hydroxide reaction of iodine, sodium ethoxide, and hydroiodic acid on iodoform the oxidation of iodoacetic acid with potassium persulfate and by reaction of potassium iodide and methylene chloride (124,125). Diiodoform is used for determining the density and refractive index of minerals. It is also used as a starting material in the manufacture of x-ray contrast media and other synthetic pharmaceuticals (qv). 

The final product of all the above processes is iron(III) oxide, a-Fe202, but its properties are deterrnined by the method of preparation. Thermal dehydration of goethite yields a pigment of lowest (4.5 g/cm ) density. The highest (5.2 g/cm ) density pigment is one prepared by two-stage calcination. The particle si2e varies from 0.3 to 4 p.m the refractive index varies from 2.94 to 3.22. 

The mineral talc is extremely soft (Mohs hardness = 1), has good sHp, a density of 2.7 to 2.8 g/cm, and a refractive index of 1.58. It is relatively inert and nonreactive with conventional acids and bases. It is soluble in hydroduoric acid. Although it has a pH in water of 9.0 to 9.5, talc has Lewis acid sites on its surface and at elevated temperatures is a mild catalyst for oxidation, depolymerization, and cross-linking of polymers. 

Zirconium oxide increases the refractive index of some optical glasses, and is used for dispersion hardening of platinum and mthenium. Very fine zirconium oxide has been used for polishing glass but ceria seems to be preferred. 

Ba(B02)2 H2O, used in flame retardant plastic formulations as a synergist for phosphoms or halogen compounds and as a partial or complete replacement for antimony oxide (see Flame RETARDANTS), is excellent as an afterglow suppressant. The low refractive index of results in greater... 

The disadvantage of this procedure is that the minerals maybe physically or chemically altered during burning. Eor example, the refractive index of clay minerals is changed the color, birefringence, and pleochroism of micas is altered carbonates are destroyed and the iron sulfides are oxidized to iron oxides. 

This technology also allows the control of refractive index profiles by doping. AH vapor-phase techniques use a vapor stream of volatile haUdes such as SiCl, GeCl, BCl, or POCl, and gases such as CI2 or O2. The reactants are oxidized and deposited onto a substrate to produce a soHd glass preform which is then drawn into a fiber. The variations of the technique differ in the way the reactants are oxidized (16). 

Other Applications. The refractive index of siUcate or borosiUcate glass can be modified by the addition of cesium oxide, introduced as cesium nitrate or carbonate. Glass surfaces can be made resistant to corrosion or breakage by surface ion exchange with cesium compound melts or solutions. This process can also be used for the production of optical wave guides (61). 

The color of pure diatomite is white, or near white, but impurities such as carbonaceous matter, clay, iron oxide, volcanic ash, etc, may darken it. The refractive index ranges from 1.41 to 1.48, almost that of opaline siUca. Diatomite is optically isotropic. 

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