Phosphate bronzes

Figure 4 Ideaiized stmcture of a diphosphate tungsten phosphate bronze containing hexagonal channels formed by the insertion of diphosphate groups (projected down the P-P axis) into the WO3 iattice of WOe octahedra (projected down a fourfold axis)...

Phosphorus compounds are very important as fertilizers (world use 1976/77 27-3 megatonnes as P2O5) but are widely used in matches, pesticides, special glasses and china ware, alloys (sleels. phosphor bronze), and metal treating (10%), detergents (40%), electrical components (e.g. GaP), foods and drinks (15%). Phosphates are an essential constituent of living organisms. U.S. production of phosphorus 1982 372 000 tonnes. 

Phosphorus is also important in the production of steels, phosphor bronze, and many other products. Trisodium phosphate is important as a cleaning agent, as a water softener, and for preventing boiler scale and corrosion of pipes and boiler tubes. 

EXTENDING SURFACE ANALYSIS OF NEW MOSFETS BASED ON NANO AND MKM SCALED CDW PHOSPHATE AND OXIDE BRONZES... 

Phosphor-athcr, m. phosphoric ether (ester of phosphoric acid, specif, ethyl phosphate), -basis, phosphorus base, -bestimmung, /. determination of phosphorus, -blei, n. lead phosphide Min.) pyromorphite. -bombe, f. phosphorus bomb. -brandgranate, /. phosphorus incendiary shell, -brei, m. phosphorus paste, -bromid, n. phosphorus bromide, specif, phosphorus pentabromide, phos-phorus(V) bromide, -bromijr, n. phosphorus tribromide, phosphorus(III) bromide, -bronze, /. phosphor bronze, -calcium, n. calcium phosphide, -chlorid, n. phosphorus chloride, specif, phosphorus pcntachloride, phosphorus(V) chloride, -chloriir, n. phosphorous chloride (phosphorus trichloride, phosphorus(III) chloride), -dampf, tn. phosphorus vapor or fume, -eisen, n. ferrophos-phorus iron phosphide, -eisensinter, m. diadochite. 

The simplest and most thoroughly studied solutions are those based on phosphoric acid at low temperatures (<35°C) which alone can fulfil all three requirements of acid solvent, film former (as metal phosphate) and diffusion agent by virtue of its viscosity. Thus copper and its main alloys of brasses and bronzes can be very effectively electropolished in 60-70% orthophos-phoric acid with the temperature maintained below 35°C under other conditions copper passivates or dissolves freely under mass transfer controlled conditions, but by varying the conditions appropriately polishing can be continued under mild agitation. An annotated polarisation curve is given in Fig. 11.7 readers are referred to recent studies for more detailed 2ispects " . 

An example of the application of Tafel analysis is provided by samples taken for a bronze montefortino helmet from the Gabriel river valley (Kelin and Ikalesken period) in the Valencian region of Requena, dated back to the Second Iron Age (see Fig. 3.13). Upon attachment to paraffin-impregnated graphite electrodes immersed in 0.50 M phosphate buffer, voltammetric signals such as depicted in Fig. 3.14 were found [183]. 

Alloys.—Phosphorus as a constituent of bronzes is chiefly valued for its deoxidising effect, which confers a great toughness on the metal. The principal alloys are those containing copper, tin, zinc, nickel, lead and antimony. The phosphorus is usually added in the form of phosphor-tin. Phosphor-coppers may be made by heating copper phosphate or copper turnings and phosphorus in crucibles at 600-800°. 8 Phosphor-bronze may contain Cu 89, Sn 11 and P 0-3 per cent.8 The phosphorus should not exceed 0-6 per cent. 

Alloys of copper and tin such as the phosphor bronzes are dissolved in nitric acid of density 1-5, and the metastannic acid, which contains all the phosphoric oxide, after ignition and weighing is fused with KCN. The aqueous solution of the melt is freed from tin globules by filtration and from traces of soluble copper and tin by H2S, then containing all the phosphorus as potassium phosphate, which is determined as described below. 

The largest series of electronically conducting materials are the phosphate tungsten bronzes. These have similar properties to oxides bronzes such as Na WOs (see Oxides Solid-state Chemistry) and are strongly colored metals or semiconductors. They are formed by inserting planes of... 

Phosphorus (0.11% of the lithosphere) is found mainly in minerals based on calcium phosphate, collophanite, the monohydrate, Ca3(P04)2.H20, and apatite, CagF(P04)3. About 90% of the phosphate rock mined is converted into fertilisers, the rest is used for making elementary phosphorus, phosphorus compounds and such alloys as phosphor bronze. For fertilisers rock phosphate is finely ground and treated with sufficient concentrated sulphuric acid to convert it to the soluble dihydrogen phosphate ... 

The data in Tables 34-1 through 34-4 show that the accuracy obtainable in the determination of an element is greatly dependent on the nature and complexity of the substrate. Thus, the relative error in the determination of phosphorus in two phosphate rocks was 1.1 % in a synthetic mixture, it was only 0.27%. The relative error in an iron determination in a refractory was 7.8% in a manganese bronze having about the same iron content, it was only 1.8%. In this example, the limiting factor in the accuracy was not in the completion step but rather in the dissolution of the samples and the elimination of interferences. 

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