Synthesis and structural characterization of two new rare-earth manganese germanates: CeMn{sub 2}Ge{sub 4}O{sub 12} and GdMnGe{sub 2}O{sub 7}
- Univ. Blaise Pascal, Aubiere (France). Lab. des Materiaux Inorganiques
- Inst. des Materiaux, Nantes (France)
Crystals of Ce{sup +4}Mn{sub 2}{sup +2}Ge{sub 4}O{sub 12} and Gd{sup +3}Mn{sup +3}Ge{sub 2}O{sub 7} were obtained during the exploration of the quaternary Ln-Mn-Ge-O system. Their structures have been determined by single-crystal X-ray diffraction: CeMn{sub 2}Ge{sub 4}O{sub 12} crystallizes in the tetragonal space group P4/nbm with a = 9.816(1) {angstrom}, c = 4.888(1) {angstrom}, Z = 2, and R = 0.026 while GdMnGe{sub 2}O{sub 7} crystallizes in the orthorhombic space group A222 with a = 4.735(1) {angstrom}, b = 7.839(2) {angstrom}, c = 13.500(3) {angstrom}, Z = 4, and R = 0.048. Both frameworks are built up from the same polyhedra, i.e., LnO{sub 8} antiprisms, MnO{sub 6} octahedra, and GeO{sub 4} tetrahedra. CeMn{sub 2}Ge{sub 4}O{sub 12} is isotypic with SrNa{sub 2}P{sub 4}O{sub 12}; the GeO{sub 4} tetrahedra are linked into Ge{sub 4}O{sub 12} rings located between layers of CeO{sub 8} and MnO{sub 6} polyhedra sharing edges. On the other hand, GdMnGe{sub 2}O{sub 7} exhibits a novel quasi-one-dimensional lattice which might be ascribed to the Jahn-Teller nature of the Mn{sup +3} ion. The structure consists of chains of MnO{sub 6} octahedra alternating with parallel chains of GdO{sub 8} antiprisms forming layers linked together through Ge{sub 2}O{sub 7} groups. A structural comparison with fluorite-related compounds as well as CeMn{sub 2}Ge{sub 4}O{sub 12} will be discussed.
- OSTI ID:
- 338439
- Journal Information:
- Journal of Solid State Chemistry, Vol. 143, Issue 2; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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