Barium chromium oxide, Ba3Cr2O8, as grown by the traveling solvent floating-zone technique

Large single crystals of the incongruently melting compound tribarium dichromium octa­oxide, Ba3Cr2O8, were grown by the traveling solvent floating-zone technique for the first time and characterized by X-ray diffraction at room temperature. The structure is composed of CrO43− tetra­hedra and Ba2+ ions. The chromium ions are found in the rare +5 valence state and form double-layered triangular lattices, which are stacked along the c axis with threefold periodicity. All atoms lie on special positions. One Ba, one O and the Cr atoms have site symmetry 3m, the other Ba atom has site symmetry \overline{3}m, and the other O atom has site symmetry m. Magnetic measurements suggest that this material is a spin dimer system with a spin-singlet ground state.