Preparation And Properties Of Bismuth Ferric Oxide Based Ferroelectric Thin Films

Bismuth ferrite thin film is a promising multiferroic materials,with a broad application prospect in photovoltaic energy storage,sensor,information storage.The preparation process and element doping have important influence on the ferroelectric properties of the films.We combined inkjet printing and sol-gel method to prepare pure phase bismuth ferrite thin films successfuly.And the ferroelectric properties of the films are improved by element doping.The main contents of this paper include:1.Stable and homogeneous pure BiFeO₃ thin films were prepared by inkjet printing through sol-gel route.During the process of preparing ink,2-Methoxyethanol was used to adjust the viscosity of the inks to meet the request for printing and appropriate polyethylene glycol 400（PEG400）was added to decrease films cracking.Additonally,BiFeO₃ thin films with no impuritis annealed at 550℃showed the best ferroelectric properties.2.The effect of annealing atmosphere on the ferroelectric properties of ink jet BiFeO₃ thin films was investigated.10%excess Bi could compensate the Bi loss,and wet air helps to crystallize and reduce the oxygen vacancies,thus improving the ferroelectric properties.3.A small amount of Na⁺dopping resulted in the phase transition from rhombohedral to pseudo tetragonal and decrese in grain size in Bi_1-xNa_xFeO₃ thin films.While the lattice parameters decreased slightly and grain size increased rapidly with the increasing in Na⁺dopping.Moreover,the dielectric constant and ferroelectric properties increased to the maximum and then decrease gradually with the mount of Na⁺increasing,and the leakage currents performanced against that.The maximum residual polarization of Bi_1-xNa_xFeO₃ film with 3%Na⁺-dopped is 51.7 C/cm².The structure and properties of Ca doped Bi_1-xCa_xFeO₃ films show a similar trend to that of Bi_1-xNa_xFeO₃ films with the change of doping content.The maximum residual polarization of Bi_1-xCa_xFeO₃ film with 4%Ca²⁺dopped is 45.6 C/cm².4.Appropriate oxygen with moisture played an important role on improving the ferroelectric properties of Na and Mn Co-doped Bi_0.97Na_0.03Fe_1-xMn_xO₃ films.