Synthesis and crystal structure of two-slab Ba1-хSrxNd2In2O7 indates

The conditions of isovalent substitution of Barium atoms by Strontium atoms in the A-position of the BaNd2In2O7 two-slab perovskite-like structure of Ba1-xSrxNdIn2O7 are established: 0 <=x<= 0.22. The tetragonal (P42/mnm) crystal structure of Ba1-xSrxNdIn2O7 phases with x = 0.1 and 0.2 was determined by the Rietveld method. Ba1-xSrxNdIn2O7 structure is based on two-dimensional (infinite in the XY plane) perovskite-like blocks of two slabs connected by vertices of deformed InO6 octahedra. Neighboring blocks are separated by a layer of NdO9 polyhedra and interconnected by O – Nd – O bonds. It is found that isovalent substitution of Barium atoms by Strontium atoms reduces the Nd – O2 interblock distance, which brings the structure of two-dimensional slab structure closer to the structure of three-dimensional perovskite and is one of the main factors of destruction of Ba1-xSrxNdIn2O7 slab structure at х > 0.2.