Physical properties of ferroelectric BI_4-xLa_xTI ₃O₁₂ nano-particles synthesized by the chemical co-precipitation method

Bi_4-xLA_xTI₃O₁₂ (BLT) nano-particles have been synthesised by the chemical co-precipitation method utilizing a polymeric precursor. The particle size decreases from 100 to 40 nm with the increase of La content (x = 0 ∼ 1) owing to the increase of a reaction temperature. The axial ratio a/b of BLT decreases with the increase of La content reflects a relaxation of structural distortion from its ideal tetragonal structure. A monoclinic to orthorhombic transition occurs at La > 0.75. The existence of the soft mode in Raman spectra above x = 0.75 demonstrates a displacive nature of orthorhombic to tetragonal phase transition. No noticeable size effect on physical properties is observed.