Synthesis and crystal structure of BaZn(CO3)F2;: revision of the structure of BaMn(CO3)F2

The synthesis and the crystal structure of two isostructural fluoride carbonates are presented. BaZn(CO3)F-2 and BaMn(CO3)F-2, obtained by hydrothermal growth (T = 650degreesC, P = 210 WPa, t = 48 h), are hexagonal, P6(3)/m, Z = 2, with a = 4.8523(8), c = 9.854(l) Angstrom for BaZn(CO3)F-2 and a = 4.9120(8), c = 9.919(1) Angstrom for BaMn(CO3)F-2. Their structures are solved by X-ray diffraction; the reliability factors are R/R-w = 0.016/0.039 and R/R-w = 0,019/0.046 for BaZn(CO3)F-2 and BaMn(CO3)F-2, respectively. The 3D network is built up from [MO3F2] (M=Zn, Mn) polyhedra and CO32- groups, which lie in (0 00 1) planes, The structures, which derive from the structure of KPu(CO3)O-2, are very similar to the structures of two fluoride borates, BaAl(BO3)F-2 and BaGa(Bo(3))F-2, recently published. (C) 2002 Editions scientifiques et midicales Elsevier SAS. All rights reserved.