Preparation and crystal structure of a new bismuth chromate: Bi8(CrO4)O11

Single crystals of a new bismuth chromate, Bi8(CrO4)O11, were prepared by hydrothermal reaction of NaBiO3·nH2O in K2CrO4 solution. The bismuth chromate crystallizes in the monoclinic space group P21/m   with a=9.657(3)a=9.657(3), b=11.934(3)b=11.934(3), c=13.868(2)Åc=13.868(2)Å and β=104.14(1)°β=104.14(1)°, Z=4Z=4 and the final RR factors are R=0.038R=0.038 and Rw=0.041Rw=0.041 for 3541 unique reflections. The crystal structure has a slab built up by (CrO4)2− tetrahedra and distorted bismuth polyhedra which are five-fold pyramids, six-fold trigonal prisms and octahedra. The distance of lone pair from nucleus for bismuth atoms ranges from 0.29 to 1.12 Å, depending on the coordination environment. Bi8(CrO4)O11 decomposes to Bi14CrO24 and a small amount of an unknown phase at 796 °C.

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