Crystal growth of barium rhenates from hydroxide fluxes

Single crystals of two new barium rhenate compositions, Ba16Re6O37 and Ba10Re3O16(OH)3, and of one new polymorph, orthorhombic Ba5Re2O12, were grown out of a barium hydroxide flux in sealed silver tubes. Ba16Re6O37 and Ba10Re3O16(OH)3 crystallize into the monoclinic C2/m system, with a = 20.577(4) Å, b = 5.8897(10) Å, c = 15.438 (3) Å, β = 92.255(10) ° and a = 1938342(9) Å, b = 5.8172(3) Å, c = 10.2925(5) Å, β = 91.7460(10) °, respectively. The orthorhombic polymorph of Ba5Re2O12 crystallizes in the space group Pnma, with a = 19.6728(10) Å, b = 5.8491(3) Å and c = 10.4648(5) Å. All the three crystal structures are related and consist of a framework of BaOx polyhedra (where x varies from six to twelve) with interpenetrating layers of ReO6 octahedra.

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