Cation disorder and structural studies on Bi4−𝑥Nd𝑥Ti3O12 (0.0 ≤ 𝑥 ≤ 2.0)

Pramana

A K Tyagi1²  P S R Krishna¹  A B Shinde¹  S J Patwe²  S N Achary1² 

[1] Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India$$;Chemistry Division; Bhabha Atomic Research Centre, Mumbai 400 085, India$$

关键词: Neutron diffraction;    X-ray diffraction;    Rietveld refinement;    crystal structure;    ferroelectric;    bismuth titanates.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Here we report the results of combined powder X-ray and neutron diffraction studies of Bi4−𝑥Nd𝑥Ti3O12 (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 Nd 3+ 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.

【 授权许可】

Unknown