Synthesis, Characterization, and X-Ray Powder Structure of K2ZrGe2O7

A potassium zirconium pyrogermanate, K2ZrGe2O7, was synthesized hydrothermally at 180°C from a mixture of zirconium propionate, GeO2, and KOH. The crystal structure was solved from in-house X-ray powder data by direct methods and Fourier analysis. Refinement of the structure was effected by the Rietveld full-pattern technique. The compound is monoclinic, space group C2/c, a=9.9619(2) ?, b=5.5578(1) ?, c=12.9555(3) ?, beta=105.169(1)°, Z=4. The structure is remarkably like that of alpha-zirconium phosphate. Zr(HPO4)2·H2O, except that the layers are crosslinked by the pyrogermanate group to form a three-dimensional lattice. Exchange of the K+ ions is minimal as they are strongly held within the confines of narrow tunnels. The relationship of this newly synthesized pyrogermanate to a sodium zirconium pyrogermanate prepared hydrothermally at 500°C and Na3H(GeO4)2 is discussed.