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物理学报. 1985, 34(7): 946-950.
doi: 10.7498/aps.34.946.
PbBi2Nb2O9的晶体结构
- 收稿日期: 1984-06-11
- 刊出日期: 2005-03-31
摘要: PbBi2Nb2O9晶体属正交晶系,空间群为D2h23-Fmmm。晶胞参数为a=5.4806(7)?,b=5.4791(7)?,c=25.416(3)?,α=β=γ=90.0(0)°,V=763.2(2)?3。单位晶胞内化学式数z=4,Dobs=7.91g/cm3,Dx=8.26g/cm3
English Abstract
THE CRYSTAL STRUCTURE OF PbBi2Nb2O9
- Received Date:
11 June 1984
- Published Online:
31 March 2005
Abstract: Crystal of PbBi2Nb2O9 belongs to orthorhombic system with space group D2h23 - Fmmm, z = 4 and cell parameters a = 5.4806(7) ?, b = 5.4791(7)?, c = 25.416(3) ?, V = 763.2(2) ?3, Dobs = 7.91g/cm3, Dx = 8.26g/cm3, μ(Mo,Kα) = 678.38cm-1, F(000) = 1608. The crystal structure was determined by the direct method (Multan-78) and Fourier-technique. The coordinations of atoms, isotropic and anisotropic thermal parameters were refined to R = 0.107 for 396 independent reflections by block-diagonal least-squares refinement technique. The Nb-O octahedra are deformed from Oh to C4v and the atoms Nb deviate 0.225 ? from the center along the directions of the 4-fold axes. The deformation of the Nb-O octahedra and the position deviation of metal ions Nb may be the structual reasons resulting in the ferroelectric properties of PbBi2Nb2O9.
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