Trigonal sodium calcium germanate, Na(2.54)Ca(1.73)Ge(3)O(9).
Single crystals of a new germanate, Na(2.54)Ca(1.73)Ge(3)O(9), have been synthesized. The structure has a six-membered ring of GeO(4) tetrahedra, which is similar to the rings of the silicate analogue Na(2)Ca(2)Si(3)O(9), and both structures contain pseudo-cubic subcells with an edge length of 3.8 A. The details of the two compounds are slightly different, however. For example, two O atoms are statistically distributed about twofold axes in the title compound, while the silicate analogue has no such O-atom distributions. In addition, the title germanate has an extra partially populated metal site containing 54 (4)% Na, with no equivalent site in the silicate analogue.
Nishi
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Saitama Institute of Technology, Fusaiji 1690, Okabe, Ohsato-gun, Saitama 369-0293, Japan. nishi@sit.ac.jp