Effect of La substitution on the struture and multiferroic properties of BiFeO3-PbTiO3 crystalline solutions

摘要

Crystalline Solutions of 0.6(Bi1- xLax)FeO3-0.4PbTiO3 (BLF-PT) for x=0, 0.1 and 0.2 have been synthesized by the solid-state reaction method. X-ray diffraction results reveal that BLF-PT of x=0 has the strong tetragonal distortion with the c/a ratio of about 1.17. However, the La substitution modifies BLF-PT into the rhombohedral structure. The dielectric loss at low frequency (102 ~ 104 Hz) is significantly reduced by addition of La. Moreover, the giant remnant polarization of 64.8 μC/cm2 is achieved for BLF-PT of x=0.2. The weak ferromagnetic phenomenon in BLF-PT is observed with the increase of La concentration. X-ray photoelectron spectroscopy (XPS) investigation shows that the valent variation of Fe3+→Fe2+ could be effectively suppressed by La substitution.