Bifeo < Sub > 3 < / Sub > Film Of Sol - Gel Preparation And Optical Properties Of The Research

Magneto-electric materials shows coexistent ferroelectric orderand magnetic order. There are few ferroelectromagnetic materials withexistence of antiferromagnetism and ferroelectricity simultaneously atroom temperature,and BiFeO₃is one of them. BiFeO₃has ferroelectricproperties with Neel temperature （TN=643K） and antiferromagnetismwith curie temperature （TC=1103K）.In this thesis,BiFeO₃powders were prepared by Solid State Reactionand BiFeO₃thin films were prepared on ITO/glass substrate by sol-gelmethod in this paper. And we studied there properties. The maincontents of this paper listed as followed:1.BiFeO₃powders were prepared by Solid State Reaction. And weinvestigate the microstructure and ferromagnetic properties of theBiFeO₃powders;2.BiFeO₃thin films were prepared on ITO/glass substrate by sol-gelmethod. And we studied the influence of different temperature on theoptical and photoluminescence properties of BiFeO₃thin films. Themain results are:（1）XRD results confirm that the polycrystalline BiFeO₃thin films haveno impurity phases such as Bi2Fe4O9.And the BiFeO₃thin films are wellcrystallized, showing smooth, uniform and crack-free surfacemorphology with well-distributed fine grains.（2）Crystallized BiFeO₃thin films annealed at600℃exhibit （110）preferential orientation;（3）Optical band-gap of2.75eV and2.71eV was confirmed forBiFeO₃thin films annealed at500℃and600℃, respectively. The shift ofband-gap was discussed in term of coarsening grain sizes as well as theexistence of amorphous phases in the films;（4）Three emission peaks were identified at462.5nm,473.7nm, 499.1nm and they arise from the electron transition from valence bandto conduction band, the Bi³⁺ related emission and the oxygenvacancies related emission respectively.