Preparation Of Co Fe2o4 By Electrodeposition And Research Of Multiferroic Films Properties

A particularly interesting subset consists of those materials characterized by the simultaneous presence of, and a coupling between, the magnetic and electric order parameters, called magnetoelectric multiferroics. Magnetoelectric multiferroics consist of intrinsic multiferroics and magnetoelectric composites. Instrinsic multiferroics character ferroelectric property,magnetic property and magnetoelectric coupling effects with itself. However, magnetoelectric composites are formed of ferroelectric materials with piezoelectric property and magnetic materials with magnetostrictive effect which are often supplied by ferrite materials.Among various ferrite materials, a spinel type of cobalt ferrite, CoFe2O4, is a well-known hard magnetic material which has been studied in details due to its high coercivity, moderate saturation magnetization, remarkable chemical stability and mechanical hardness, as well as the largest magnetostriction in the spinel ferrites, by which was used in combination with ferroelectrics to produce magnetoelectric effect. In addition, more and more attention has been attracted on how to control the structure and morphology of deposited films in recent years.In this work,Cobalt ferrite(CoFe2O4, CFO) films with dendritic arrays, were prepared on Pt/Ti/SiO2/Si substrates by using a combined electrochemical method of electrodeposition and anode activating. Firstly, the CoFe2(CF) alloy films were electrodeposited from the solution of Fe2SO4 and Co2SO4 at room temperature. Then CFO films were prepared by anode activating and annealing the alloy films. Effects of preparation conditions on the crystalline structure, microtopography and properties of CFO films were investigated. Interestingly, it is different from the reported results that the smooth CFO films were obtained after annealing CF films in air condition even if without anodization, while controllable dendritic columnar arrays of CFO were observed after anode activating and annealing process. Anodization process can not convert CF alloy into CFO films as reported. It was not necessary to form CFO films, but had an important effect on morphology of CFO films, and CFO films with desirable dentritic morphology could be adjusted by controlling anode-activating process parameters.X-ray diffractometry(XRD), and X-ray photoelectron spectroscopy(XPS) were used to characterize the crystalline structure.Scanning electron microscope(SEM) and atomoc force microscope(AFM)were used to characterize morphology of the films. Vibrating sample magnetometer(VSM) was used to measure the magnetic properties of the films.And also ferroelectric hysteresis loop measuring instrument and other electric measuring instruments were used to measure composite films. Elecrtochemical workstation and xenon light were used as optics measurement.