Pigmented phosphors

It is easy to dope metal ions in metal hydrazine complexes as well as to make solid solutions of them (discussed in Chapter 4). The combustion of these metal-ion substituted metal hydrazine carboxylate complexes in air yield the corresponding nanocrystalline oxide materials with interesting catalytic, magnetic, and dielectric properties, having applications as phosphors, pigments, and so on. A few examples of the interesting... 

CdS Solar cells photoconductor in photocopying phosphors pigment... 

Luminescent Pigments. Luminescence is the abihty of matter to emit light after it absorbs energy (see Luminescent materials). Materials that have luminescent properties are known as phosphors, or luminescent pigments. If the light emission ceases shortly after the excitation source is removed (<10 s), the process is fluorescence. The process with longer decay times is referred to as phosphorescence. 

Sedimentation analysis is suitable for a wide variety of materials and is used for both quaHty control and research work, such as agglomeration studies (56), and gives well-defined, relatively high resolution results. The technique has been employed in the evaluation of soils, sediments, pigments, fillers, phosphors, clays (qv), minerals, photographic haHdes, and organic particles (57,58). 

Titanium pyrophosphate [13470-09-2] TiP20y, a possible uv reflecting pigment, is a white powder that crystallizes ia the cubic system and has a theoretical density of 3106 kg/m. It is iasoluble ia water and can be prepared by heating a stoichiometric mixture of hydrous titania and phosphoric acid at 900°C. 

In paints, zinc oxide serves as a mildewstat and acid buffer as well as a pigment. The oxide also is a starting material for many zinc chemicals. The oxide supphes zinc in animal feeds and is a fertilizer supplement used in zinc-deficient soils. Its chemical action in cosmetics (qv) and dmgs is varied and complex but, based upon its fungicidal activity, it promotes wound healing. It is also essential in nutrition. Zinc oxide is used to prepare dental cements in combination with eugenol and phosphoric and poly(acrylic acid)s (48) (see Dental materials). 

CdSe forms sohd solutions with CdS which are used as pigments ranging ia color from orange to deep maroon and are called cadmium sulfoselenides. Other uses are ia photocells, rectifiers, lumiaous paiats, and as a mby colorant for glass manufacture. CdSe currentiy sells for 1.50/g as phosphor-grade (99.999% purity) material. 

Cobalt is used as a blue phosphor in cathode ray tubes for television, in the coloration of polymers and leather goods, and as a pigment for oil and watercolor paints. Organic cobalt compounds that are used as colorants usually contain the azo (51) or formazon (52) chromophores. 

Etch primers are widely used. They are mostly based on polyvinyl butyral and contain chromates and phosphoric acid. They are said to act both as primers and as etching solutions because it is believed that the chromates and phosphoric acid form an inorganic him, which provides adhesion, while oxidised polyvinyl butyral provides an organic him. For direct application to new galvanised steel, the best known primers are based on calcium orthoplumbate pigment and metallic lead, but these are now less used for environmental reasons. Zinc-dust paints and zinc-phosphate pigmented paints are also used, but the trend is to use pretreatments to assure good adhesion. 

The reactions which take place when the mixed etch primer is applied to a metal are complex. Part of the phosphoric acid reacts with the zinc tetroxychromate pigment to form chromic acid, zinc phospliates and zinc chromates of lower basicity. The phosphoric acid also attacks the metal surface and forms on it a thin chromate-sealed phosphate film. Chromic acid is reduced by the alcohols in the presence of phosphoric acid to form chromium phosphate and aldehydes. It is believed that part of the chromium phosphate then reacts with the resin to form an insoluble complex. Excess zinc tetroxy chromate, and perhaps some more soluble less basic zinc chromes, remain to function as normal chromate pigments, i.e. to impart chromate to water penetrating the film during exposure. Although the primer film is hard... 

Thus, we have two units of measurement of intensity. One is related to scattering from a surface, L, i.e.- in foot-lamberts and the other is related to emittance, H, i.e.- in lumens per square foot. Although we have assumed "white" light up to now, either of these two can be wavelength dependent. If either is wavelength dependent, then we have a pigment (reflective- but more properly called scattering) with intensity in foot-lamberts, or an emitter such as a lamp or phosphor (emittance) with intensity in lumens. 

Cochineal pigments are extracted from dried bodies of female insects with water or with ethanol the result is a red solution that is concentrated in order to obtain the 2 to 5% carminic acid concentration customary for commercial cochineal. For carmine lakes, the minimum content of carminic acid is 50%. An industrial procedure applied in Spain uses ammonium hydroxide as the extracting agent and phosphoric acid as the acidifying agent. For analytical purposes the extraction is carried out with 2 N HCl at 100°C. The chemical synthesis of carminic acid has also been reported and is the subject of European and United States patents. ... 

Fluorescent lamp coatings, ethylene oxide polymers in, 10 688-689 Fluorescent lamps, mercury in, 16 41 Fluorescent lighting phosphors, cerium application, 5 688-689 Fluorescent photo-induced electron transfer (PET) sensor, 24 54 Fluorescent pigments, for inks, 14 318 Fluorescent probes, 11 150 16 388 modified-base oligonucleotides as, 17 633-634... 

Cadmium sulfate (CdS), also called orange cadmium, is used to produce phosphors and fluorescent screens. It is also used as a pigment in inks and paints, to color ceramics glazes, in the manufacture of transistors in electronics, photovoltaic cells, and solar cells, and in fireworks. 

Uses. The metal is used in electroplating, in solder for aluminum, as a constituent of easily fusible alloys, as a deoxidizer in nickel plating, in process engraving, in cadmium-nickel batteries, and in reactor control rods. Cadmium compounds are employed as TV phosphors, as pigments in glazes and enamels, in dyeing and printing, and in semiconductors and rectifiers. 

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