Implant Method Of Layered Iron Material And Its Performance Study

Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist and there is a coupling between them, have become one of the hottest topics of condensed matter physics and materials science in recent years. Bismuth layer-structured single-phase magnetoelectric multiferroics is one of widely studied materials because of its good FE properties at room temperature (RT). However, the magnetic nature of the materials at RT is still weak and requires improvement. Furthermore, the mainly research about them focus on the studieds of the four-layered of higher-layered Aurivillius multiferroic compands. The main purposes of this dissertation are aimed at the inserting the magnetic octahedral group into BIT, it can be summarized into following three parts:(1) Different proportions of magnetic unit (1-x)BFO and (x)BCO were incorporated into the BIT powder, and then results in a composition of Bi5Fe1-xCoxTi3O15(BFCT-x, x=0.0～0.8). The Bi5Fe1-xCoxTi3O15(x=0.0,0.2,0.4,0.5,0.6, and0.8) multiferroic ceramics were synthesized in two steps using the solid state reaction technique. X-ray diffraction patterns show that the samples are four-layer Aurivillius phases. At room temperature (RT), the samples present a remarkable coexistence of ferromagnetism (FM) and ferroelectricity (FE). The remnant polarization (2Pr) reaches a greatest value of14μC/cm2at x=0.6. Remnant magnetization (2MT) increases first and then decreases, the greatest2Mr of7.8menu/g when x=0.5. The magnetic properties of x=0.4is similar with that of x=0.6, indicating that magnetic properties mainly from the coupling between Fe3+and Co3+ions, rather than its own magnetic moment.(2) Electrical and magnetic properties of Pr-doped BFCT compounds were investigated. X-ray diffraction patterns shows that the four-layer Aurivillius phase was formed successfully. With x increases,2Mr decreases first and then increases, the greatest2Mr of0.57emu/g at x=0.75. The remanent polarization (2Pr) are increased by such donor doping, the greatest2Pr is12.87μC/cm2at x=0.45. The enhanced properties are thought to be the the restraint of oxygen vacancies because of Pr3+and Pr4+.(3) The systematic fabrication of Bi5Fe0.5Co0.5Ti3O15thin films deposited on Pt/Ti/SiO2/Si substrates using pulsed laser deposition (PLD), where randomly oriented (BFCT-1) and (0010) oriented texture (BFCT-2) were obtained. At room temperature, the BFCT-1and BFCT-2thin films exhibit saturation magnetization (2Ms) of0.56emu/cm3and1.05emu/cm3, respectively. On the other hand, at RT, the remnant polarization (2Pr) of BFCT-1and BFCT-2films are measured to be55.4μC/cm2and34.8μC/cm2, respectively. The normalized polarization of BFCT-1film increases to about150%and the P-E loops of after fatigue exhibits leaky characteristic as shown in its round shape. While for BFCT-2film, its normalized polarization decreases to93%after4.5×107cycles, and then increases to about100%after almost109switching cycles.The monodisperse polystyrene microspheres which have good sphericity are successfully synthesized by soap-free polymerization, using styrene(St) as raw materials and potassium persulfate (KPS) as initiator. The effects of styrene’s and potassium persulfate’s concentration on particle diameter and its distribution are mainly investigated. The results show that different size polystyrene microspheres can be obtained by changing styrene and potassium persulfate concentration, and the distribution of microspheres is good. Moreover, three-dimensionally ordered polystyrene colloidal crystal is prepared with the monodisperse polystyrene microspheres using self-assembly. And then, a facile approach of layer-by-layer depositing and hydrolysis of ZnO is developed to fabricate three-ordered ZnO film.