Dissertation > Excellent graduate degree dissertation topics show

Effect of Eu and Co Codoping on the Dielectric and Magnetoelectric Properties of BiFeO3 Ceramics

Author: FuHePeng
Tutor: ChangFangGao
School: Henan Normal
Course: Condensed Matter Physics
Keywords: Dielectric constant Dielectric loss Magnetoelectric coupling resistivity
CLC: O483
Type: Master's thesis
Year: 2011
Downloads: 69
Quote: 0
Read: Download Dissertation

Abstract


The effects of A-site Eu doping and B-site Co co-doping on the dielectric and magnetoelectric properties of BiFeO3 were investigated. Series of specimens of Bi1-xEuxFe1-yCoyO3 （x = 0, 0.05, 0.1, 0.01; y = 0, 0.01, 0.05, 0.1） were prepared by rapid liquid phase sintering method. The crystal structure of Bi1-xEuxFe1-yCoyO3 samples was examined by using a DX-2000 X-ray diffractometer （XRD）. The dielectric and magnetoelectric properties of all the samples were studied using Agilent 4294A impedance analyzer in a frequency range from 40 Hz to 1 MHz. The resistivity of samples at room temperature was measured using a HP3458A multimeter. The results indicate that:（1） All the ceramic samples Bi1-xEuxFe1-yCoyO3 have the rhombohedral structure with R3c space group. No impurity phase peaks appear in the image of XRD for undoped BiFeO3 and slightly doped Bi0.99Eu0.01Fe0.99Co0.01O3. An impurity phase Bi12Co0.6O18.8 was detected between 25 and 30 degrees of 2 theta when the quantity of Eu and Co reached 0.05 and above. Therefore, the best doping level of Eu and Co should not be more than 0.05 respectively.（2） The dielectric constants of all samples decrease with increasing frequency. The dielectric constants of Bi1-xEuxFe1-yCoyO3 is larger compared with those for undoped BiFeO3. However, the dielectric constants of undoped BiFeO3 depend less on the frequency, indicating higher frequency stability than those doped samples. At a particular frequency, the dielectric constant increases with the Eu and Co content first and then decreases with increasing Eu and Co doping. The dielectric constant of Bi0.99Eu0.01Fe0.99Co0.01O3 ceramic sample is 1790.5 at 1000Hz, which is nearly an order of magnitude larger than that for undoped BFO. The dielectric loss of all the samples decreases with frequency. A small amount of Eu, and Co doping reduces dielectric loss of BFO significantly. The dielectric loss of Bi0.99Eu0.01Fe0.99Co0.01O3 reaches a minimum, but it varies more complicatedly with further increased doping. The dielectric loss is biggest when x= 0.05 and y= 0.05. It falls again when x and y = 0.1.（3） At a particular frequency, the dielectric constant of undoped BiFeO3 changes little with magnetic field, indicating a weak magnetoelectric coupling. Dielectric constants of Eu and Co co-doped samples Bi1-xEuxFe1-yCoyO3 increase with magnetic field, suggesting stronger magnetoelectric coupling effect. In particular, the magnetic-dielectric coupling coefficient （MD） for samples Bi0.99Eu0.01Fe0.99Co0.01O3 and Bi0.95Eu0.05Fe0.95Co0.05O3 in a magnetic field of 4500Gs was measured at 10 kHz to be 3.2% and 4.37% respectively, increased 20 and 25 times from that for undoped samples. To improve sample magnetoelectric coupling coefficient the best doping quantity should be x= 0.05, y = 0.05.（4） The resistivity of Eu and Co co-doped spemens increases with the Eu and Co content until x, y = 0.01where the resistivity reaches a maximum, and then decreases with increasing Eu and Co doping. Minimum resistivity is reached at x, y = 0.05. Compared with Eu, the effect of Co doping on the resistivity is larger; when the Co content equal or greater than 0.05, the resistivity of Eu and Co co-doped samples is lower than that for undoping sample.

Related Dissertations

  1. Study and Preparation of BaTiO3-based NTC Ceramic Thermistors,TQ174.1
  2. Predicting Model of Coal Fired Fly Ash Resistivity,X701.2
  3. DC Law exploration infinity pole impact and Calibration Technology,P631.3
  4. Synthesis, In-situ Mechanical and Electrical Properties of One-dimentional Carbide Nano-materials Generated from Plant Fibers,TB383.1
  5. Research of AZO Thin Films for Amorphous Thin Film Solar Cells,TM914.42
  6. Study on Influence of Polyacrylamide on Properties of Cement Paste,TU528
  7. Excite polarization method tunnel engineering geological exploration Imaging Method research,U452.11
  8. Study on Fast Freeze, Uniform Microwave Thawing and Microwave Cooked for Convenience Dishes,TS255.3
  9. Advanced EFA electrical failure analysis the positioning technology PFA physical verification technology research,TN407
  10. High pressure and high temperature to explore synthetic β-FeSi_2 thermoelectric materials,TN304.2
  11. Research and Implementation of Formation Resistivity Measurement Based on Electromagnetic Wave Propagation Theory,P631.811
  12. Theoretical Research on Radial Investigation Depth of Electromagnetic Induction Logging,P631.81
  13. Investigation on Typical Electrical Resistivity Model of Domestic Landfill-leachate Contaminated Soil,X53
  14. The Preparation and Performance Study of Resin-Based Magnetoelectric Films,TB383.2
  15. Preparation of Nano-copper Thin Film and Basic Research of Its Laser Shock Modifing,TB383.1
  16. Carbon nanotubes prepared and its application in the field of photovoltaic Prospects,TB383.1
  17. Study of Medium Temperature Sintering of X9R BaTiO3-based Ceramics,TQ174.1
  18. Study on Dielectric Properties and Optical Basicity of Aluminoborosilicate Glasses,TQ171.1
  19. Study on the Properties of SnO2 Ceramics Doped CeO2, La2O3,TQ174.1
  20. Design and Application for Jiangxi 200kV Transmission Line Towers Grounding Device,TM862
  21. Grid ground engineering applications,TM862

CLC: > Mathematical sciences and chemical > Physics > Solid State Physics > Defects in Solids
© 2012 www.DissertationTopic.Net  Mobile