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RESEARCH PRODUCT

Crystal Structure of the Microwave Dielectric Resonator Ba2Ti9O20

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A single-crystal X-ray study of dibarium nonatitanate, Ba2Ti9O20, yielded the triclinic space group P 1 with a=0.7471(1), b= 1.4081(2), c= 1.4344(2) nm, α=89.94(2)°, β= 79.43(2)°, γ= 84.45(2)°, V = 1.476 nm3 Z = 4, and Dx= 4.61 Mg/m3. A refinement of atomic coordinates and isotropic thermal parameters led to a residual of 0.03. The structure consists of hexagonally closest-packed layers of Ba and O atoms in the sequence (hch)3. All Ti atoms reside in octahedral interstices of this closest packing. The various Ti coordination octahedra share only edges and corners with each other. One-half of the Ba atoms is twelve-coordinated by oxygen atoms, the other half is eleven-coordinated.