Refractive index, of titanium

Antireflection coatings are used over the silicon surface which, without the coating, reflects ca 35% of incident sunlight. A typical coating consists of a single layer of a transparent dielectric material with a refractive index of ca 2, which is between the index of siUcon and ait or cover material. Materials such as titanium dioxide, tantalum pentoxide, Ta20, or siUcon nitride, Si N, ca 0.08-p.m thick are common. The coating and a physically textured... 

The refractive index of these pigments is about 1.5, which means that they give a transparent blue when used in paints and clear plastics. Opacity can be increased by adding small amounts of titanium dioxide. The principal failing of ultramarine is its lack of resistance to acid, which can even decompose the pigment if there is sufficient available. Coated grades are made with substantially improved acid resistance. 

In one example, the colloidal structure, is made by sedimentation of polystyrene beads, giving voids in the range 120-1000 mn, and the voids are filled with TiO generated from titanium tetrapropoxide. The polystyrene bead lattice is then removed by calcining to give an iridescent material, but not with a full photonic band gap. In this case one of the controlling factors is the refractive index of the matrix, which needs to be greater than 2.8. 

Zinc Sulfule. Whereas zuic sulfide is important mainly as a component of the composite white pigment lithopone. it also has a limited use as a single pigment After titanium white, it has the second highest refractive index of all the while pigments. However, its chemical and thermal resistances are inferior to those of TlO. ... 

The refractive index of a pigment at each wavelength is determined by its crystal structure. Titanium dioxide pigments (rutile and anatase) differ from each other and from other white pigments or crystalline substances, like silicon dioxide, in the proportion of radiant energy that is transmitted, absorbed, or re-... 

Zinc sulfide has the next highest refractive index to titanium dioxide and zirconium oxide making it a very efficient pigment. The spectrum of absorption of zinc sulfide resembles more closely anatase than rutile. Because it does not absorb certain UV wavelength, zinc sulfide is useful as a pigment for UV curable materials. 

Refractive index influences light scattering in fillers and pigments. A correct choice in the refractive index of the particulate material and binder permits a formulation of transparent materials containing fillers (for further information on light scattering see Chapter 2, especially section on titanium dioxide and Section 5.3). Table 5.16 gives an overview of refractive indices of various fillers. 

Plasticizers which have been used successfully include polyethylene tetrasulfide, polyethylene diacetate tetrasulfide, dimercaptobutane diallyl tetrasulfide, and the (mercaptoethyl) cyclohexanethiols (6, 50, 51,52), The development of yellow and other colors for highway marking paints was accomplished easily. However, a white paint which meets color and reflectance specifications is difficult to prepare. The absorption characteristics and high refractive index of elemental sulfur present formidable problems. The simple addition of titanium dioxide and other white pigments does not produce a white paint, and masking agents or other additives usually must be incorporated. 

Titanium dioxide (TiO ) has the highest refractive index of any material commonly used in papermaking, and as a result generates the highest light-scattering coefficient. It is found commonly throughout the world, but at relatively low levels of purity. Most often it is naturally found in beach sands. 

The refractive index of water is 1-33. For diamond it is 2-42, but rutile titanium dioxide has a higher refractive index than any other transparent material 2 76. 

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