Abstract
Here we report the results of combined powder X-ray and neutron diffraction studies of Bi4−x Nd x Ti3O12 (0.0 ≤ x ≤ 2.0) compositions. The parent Bi4Ti3O12 has an orthorhombic lattice (space group: B2cb) with unit cell parameters a = 5.4432(5) Å, b = 5.4099(5) Å and c = 32.821(2) Å, and V = 966.5(1) Å3. This orthorhombic lattice is retained in all the studied compositions. The unit cell parameters gradually decrease with Nd3+ ion concentration with a discontinuity at x = 0.75. Orthorhombicity of the lattice decreases with increase in Nd3+ content in the lattice. The orthorhombic unit cell parameters for a representative Bi2Nd2Ti3O12 composition are: a = 5.3834(9), b = 5.3846(9) and c = 32.784(1) Å. The observed orthorhombic distortion at x = 2.0 is very small and thus the crystal structure apparently has a pseudo-tetragonal lattice. In addition, Nd3+ preferentially substitutes in the perovskite slab of the Aurivillius structure. The fraction of Nd3+ in the fluorite slab increases with increase in Nd3+ contents.
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Achary, S.N., Patwe, S.J., Krishna, P.S.R. et al. Cation disorder and structural studies on Bi4−x Nd x Ti3O12 (0.0≤x≤2.0). Pramana - J Phys 71, 935–940 (2008). https://doi.org/10.1007/s12043-008-0203-0
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DOI: https://doi.org/10.1007/s12043-008-0203-0
Keywords
- Neutron diffraction
- X-ray diffraction
- Rietveld refinement
- crystal structure
- ferroelectric
- bismuth titanates