Crystal Structure of Silicon Pyrophosphate (Form I) from Powder Diffraction Data
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The crystal structure of silicon pyrophosphate (Form I) was solved from X-ray powder data and refined by the Rietveld method. The crystals belong to the hexagonal space group P63 with a = 4.7158(3) Å and c = 11.917(1) Å. There are two SiP2O7 traits in the unit cell. Both the P atoms and the Si atom are located on threefold axes. The silicon atoms are situated in the ab plane at z = 0 and 1/2. One of the P atoms of the pyrophosphate group is located slightly above the plane at z = 0 while the other is slightly below the plane at z = 1/2. Thus, the structure resembles the layer structure of α-zirconium phosphate. The layers in the present case, however, are held together by the P-O-P bonds. The relationship between this structure and those of the other pyrophosphates and the layered M(HPO4)2 phases is discussed. © 1994 Academic Press, Inc.
author list (cited authors)
Poojary, D. M., Borade, R. B., Campbell, F. L., & Clearfield, A.