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Abstract
Dehydration and calcination of nickel tetracaesium cyclotriphosphate hexahydrate NiCs4(P3O9)2· 6H2O under atmospheric pressure between 25 and 700°C was studied by IR spectroscopy, X-ray diffraction, TGA, and DTA. This study allowed the identification and crystallographic characterization of a new phase, NiCs4(PO3)6, obtained between 300°C and 650°C—the melting point of the compound. NiCs4(PO3)6 crystallizes in the hexagonal system, space group P31c, with Z = 2, a = b = 11.602(1) Å, c = 9.078(1) Å, V = 1058.2 Å3, M(20) = 80, and F(27) = 51(0.0007;79). The kinetic characteristics of the dehydratation of NiCs4(P3O9)2· 6H2O were determined and discussed, and its thermal behavior was compared. The IR spectrum of the salt was examined between 4000–400 cm− 1. On the basis of our results on calculations of the IR normal frequencies for the P3O9 3 − cycle with D3h symmetry, theoretical predictions for different possible symmetries, and based on the results of X-ray diffraction studies, a symmetry of the cycle was proposed.