Study Of The Influence To Bismuth Ferrite Thin Film’s Ferroelectricity Doping CE And CR

BiFeO3 thin film has multiferroic properties at room temperature, it has ferroelectrical and antiferromagnetic properties.Microstructure of Bismuth Ferrite belongs to R3c points of perovskite symmetrical trigonal system structure. Due to high Curie temperature and Neel temperature of BFO thin film, It has a broad application prospects such as Ferroelectric memory, Transducer and Optic holography memory in the future, So many scholars studied intensely in the world.In this paper, we used Sol-gel method, which is one of Chemical method.Material quality concentration is 0.2mol/L, polymeric pecursor solution of pure BiFeO3, Bio.9Ceo.iFeO3 and BiFe0.9Cr0.1O3 thin film have been prepared. After we plated BiFeO3, Bi0.9Ce0.1FeO3and BiFe0.9Cr0.1O3 thin film on the Platinum substrate by using the Spin Coater.At last, A series of performance of BFO thin film, such as crystal structure tested by X-ray diffractometer, surface topograph-y tested by scanning electron microscope, the atomic vibration energy can be tested by Raman measurement, Photoelectron spectroscopy tested binding energy, then ferroelectric and leakage current of BFO thin film tested throw the multiferroic tester.(1) The influence of doping Ce element for BFO thin film are follows:surface morphology becomes more density and a lot of holes are reduced obviously by surface morphology test. XRD result showed, peak 104 and 114 of BFO thin film nearby 32° degrees combined into a peak after doping Ce element. The cause is attributed to the changing phase structure that original symmetrical trigonal system changed into coexistence phase of tetragonal crystal systemand orthorhombic system after doped Ce. The result of Raman test showed that Phonon modes A1-1、Ai-2、E-2 and Ai-3 have red shift, and the peak at 428.25cm-1 is disappeared.The test of XPS found that Fe2+ ions, and oxygen vacancy reduced after doped Ce. By testing the leakage current and ferroelectricity of thin film, due to Fe2+ ions reducing, ferroelectricity of BFO thin film enhanced,leakage current reduced two order of magnitude, and then remanent polarization and saturated polarization increased to 27.07μC/cm2 and 49.22μC/cm2 from 6.22 μC/cm2 and 25.10 μC/cm2 respectively..(2)The influence of doping Cr element for BFO thin film are follows:surface morphology test shows that a lot of holes are reduced and granular sensation of surface morphology were not usually obvious, and asperity heights becomes evident. In addition to pure phase ferrite bismuth peaks, there is a new peaks nearby 27.9°, this is main peak of (211) crystal orientation of BiCrO3, and the peak of (420) and (422) were seated nearby 52.9° and 57.6°, these phenomenon invested by XRD test. This shows that crystal structure of pure BFO thin film turned into coexistence phase of BFO and BCO thin film from original symmetrical trigonal system. Vibration modes A1-1(cm-1)、 A1-2(cm-1)、E-1(cm-1)、 E-2(cm-1)、E-7(cm-1) of BFO located at 79.09 cm-1、140.34 cm-1、220.83 cm-1、264.87 cm-1、613.59 cm-1,which happened blue shift to 99.62cm-1、 140.51cm-1、222.29cm-1、268.54cm-1、682.61cm-1, and vibration modes A1-3(cm-1)、E-4(cm-1)、E-6(cm-1) were seated at happen blue shift, they were located at 170.29 cm-1、342.98 cm-1、506.34 cm-1. Phonon modes E-3 and E-5 disappeared, and E-8 appeared after Cr-doped. These also illustrated the change of phase. Fe2+ ions decreased from XPS test, leakage current of pure BiFeO3 and BiCr0.1Fe0.9O3 reduced by testing multiferroic. But ferroelectricity is not improved, instead to be reduce. Cr3+ ions replaced Fe3+ ions, which may destroy symmetry of structure, and polarization of BFO film weakened.