Structure of cadmium ultraphosphate Cd2P6O17 crystals. Structural motives of phosphorus-oxygen anions in ultraphosphates

Structural investigation of Cd2P6O17 crystals is conducted. The monoclinic lattice parameters are: a=7.566(2), b-5.486(1), c=18082(3)A, γ=111,1(1) deg. Space groups P21/n, Z=2. The structure is solved using the method of heavy atom, full matrix specification of MLS in anisotropic approximation being conducted. The structure basis is anion lattice [P6O17] sub(infinity) with fourteen member rings and other than in Sr2P6O17 alternation of 'ultra'- and 'meta'-phosphate tetrahedrons. The atoms are located between the lattices and are coordinated octahedrically by two oxygen atom threes from neighbour lattices. Conducted is comparison of structural grounds of anion part of Cd and Sr ultraphosphates, and also MnP4O11 and ultraphosphates of rare earth elements M3P5O14. The structures of the compounds investigated do not have analogues among silicates