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The crystal structure of the cuprate Sm 2 Ba 4 Cu 2 O 9 was determined and refined via Rietveld method on an X-ray powder diffraction pattern. The sample was prepared from Sm 2 O 3 , CuO, and BaCO 3 in several heating cycles. The compound Sm 2 Ba 4 Cu 2 O 9 crystallizes isotypically to the corresponding neodymium cuprate with slightly smaller lattice parameters ( a =12.0496(3) A, c =3.8649(1) A) in the space group P 4 n2. The main structural particularity is the Cu–O sub-structure with Cu coordinated by five oxygen atoms forming elongated pyramids. The CuO 5 -polyhedra share two corners leading to infinite [CuO 3 O 2/2 ]-chains. The whole structure can be described as a [Sm 2 Cu 2 O 8 ] network with channels filled with [OBa 4 ] polyhedra. |
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