Calcium pentaphosphate

C2 domains, 46 460-465 y-carboxyglutamic acid sites, 46 465 70 Calcium nitrate, preparation of, 6 125 Calcium pentaphosphate, 4 37-38 Calcium phthalocyanine, preparation of, 7 ... 

Among condensed phosphate systems with polyvalent cations, the very complicated calcium salts have been much studied and a great number of compounds have been detected, often with several modifications (5, 27, 28, 34, 54, 79, 186, 137, 191, 198, 204, 211, 276, 805, 830). In this system special interest attaches to the occurrence of crystalline cross-linked phosphates (see Section V) and of calcium pentaphosphate, CayiPsOis (see Section IV,D,/). The end-product obtained by heating Ca(H2P04)2 in the free atmosphere is the high-molecular calcium polyphosphate, which crystallizes in several forms. The condensed strontium phosphates (246, 805) are similarly complicated and cannot readily be made the subject of a brief review. 

Apart from tri- and tetra-phosphates, which, like the familiar pyrophosphates, belong to this group, only calcium pentaphosphate has been obtained in a crystalline form. It is formed as so-called tromelite in the form of plates or fibrous crystals on tempering melts of the corresponding composition at temperatures between 920 and 990°C (136). That tromelite is in fact a pentaphosphate Ca7(P60i6)2 can be proved by paper chromatog-... 

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