Dissertation > Excellent graduate degree dissertation topics show

Fabrication and Microwave Absorbing Properties of BaFe12-x (Ni （0.5）Cu0.5Zr)x/2O19 Ferrite

Author: HeCaiJun
Tutor: HuoDeZuo
School: Hangzhou University of Electronic Science and Technology
Course: Physical Electronics
Keywords: Ba ferrite microwave absorbing properties sol-gel method polyaniline cenosphere BaFe9(Ni0.5Cu0.5Zr)3/2O19 coating
CLC: TM277
Type: Master's thesis
Year: 2009
Downloads: 41
Quote: 0
Read: Download Dissertation

Abstract


The microwave absorbing materials have being taken much more attention due to the rapid growing of electronic technique, radar and microwave communication, especially the need of Anti-electromagnetic interference, stealth technology and microwave unreflecting chamber. Ferrites are important microwave absorbing materials because they have both dielectric loss and magnetism loss. Due to its strong anisotropy、large imaginary part of complex permittivity and permeability, the M-type Ba ferrite can meet the need of modern microwave absorbing materials with thin coating、band width、strong absorbing and light weight through element substitution、control pattern of grain and nanometer.In this work, we have successfully synthesized M-type ferrites BaFe12-x(Ni0.5Cu0.5Zr)x/2 O19 （x=0,1,2,3） and BaFe9 (Ni0.5Cu0.5Zr)3/2 O19 shell coated on the surface of cenospheres by using sol-gel method. Composites of BaFe 9 (Ni0.5Cu0.5Zr)3/2 O19/polyaniline were prepared by in-situ polymerization. The phase、crystal structural、microstructure and electromagnetic properties of the samples were analyzed by X-ray diffraction （XRD）, scanning electron microscope （SEM） and vector network analyzer. Our main results are summarized as follows:（1） Substituting Ni-Cu-Zr for Fe, M-type ferrites BaFe12-x(Ni0.5Cu0.5Zr)x/2O19 （x=0,1,2,3） were synthesized by using sol-gel method. The results indicate that: the structures of diffraction peaks of the element substituted samples （x=1, x=2） are consistent with those of the un-doped sample. The peaks shifting to the smaller angle suggests that Ni-Cu-Zr can substitute Fe3+ in BaFe12O19 to form the single phase ferrites. In the XRD diffraction pattern of sample x = 3,there are some weak unknown peaks except the characteristic peaks of BaFe12O19, which indicates that there is 2nd phase for the samples with x 3. The samples with x= 0, 1, and 2 have small reflection rate within the frequency range of 2-18 GHz, but the sample with x = 1 has a resonance peak at 15.8GHz with the maximum reflection rate of - 9.24 dB （thickness of 2 mm）.≥（2） Composites of BaFe9 (Ni0.5Cu0.5Zr)3/2O19/polyaniline were prepared by in-situ polymerization. It is found that composites of BaFe9 (Ni0.5Cu0.5Zr)3 /2 O19/polyaniline exhibit good microwave absorbing properties. The composite of BaFe9 (Ni0.5Cu0.5Zr)3/2O19/PANI （ mass ratio of 1:1, thinness of 2 mm ） has the maximum reflection rate of - 21.7 dB at 11.8 GHz. Keeping the maximal reflecting rate, the resonance frequency can be tuned by changing their thickness.（3） The single phase of BaFe9(Ni0.5Cu0.5Zr)3/2O19 can be coated on the cenospheres. Compared with the electromagnetic properties of BaFe9 (Ni0.5Cu0.5Zr)3 /2 O19, which also prepared by sol-gel method, their dielectric loss tangent and magnetic loss tangent have different frequency dependences. The absorbing properties of BaFe9 (Ni0.5Cu0.5Zr)3/2 O19 coated on the cenospheres are worse than that of single BaFe9 (Ni0.5Cu0.5Zr)3/2 O19 at frequency range of lower 11GHz, and are better in higher frequency range. In order to achieve good absorbing property,it is important to choose appropriate cenospheres and control the thickness of coating.

Related Dissertations

  1. Study on the Synthesis Bi3.25La0.75Ti3O12（BLT） Nanotubes and Nano Wires,TB383.1
  2. The Preparation of Polyaniline-Metal Complex and the Study on Its Catalytical Property,O634
  3. Preparation and Anticorrosion Properties of Doped Polyaniline/Epoxy Coating,TQ637
  4. Preparation and Property Study of Polyaniline/Polyester Composite Conductive Fabric,TS195.6
  5. Research on Electrochemical Synthesis and Application of Conductive Polyaniline,O633.21
  6. Polyaniline / short fiber reinforced natural rubber properties,TQ330.1
  7. Cobalt Ferrite and Its Performance,O611.4
  8. SnO 2 / CNTs composite Controllable Preparation and Gas Sensitivity Study,TB383.1
  9. Preparation of polyaniline nanostructures , characterization and biomedical applications,TB383.1
  10. Synthesis and Characterization of Polyaniline Micro/nano Structure and Its Composites,TB383.1
  11. The Research on Preparation Technology and Sintering Behavior of Rare Earth Aluminates (Dy3Al5O12、 NdAlO3、LaAl11O18),TB383.3
  12. Studies of High Refractive Index Materials Prepared by Nano ZrO2 and TiO2 Hybrid Silicone Epoxy Resin,TB383.1
  13. Preparation and Characterization of Al2O3/C Hybrid Aerogels and Al2O3 Aerogels,O648.17
  14. The Preparation of Metallic Fabrics with PD-Free Activation and Research of Its Properties,TS106
  15. The Study on Properties of Desulfurization and Denitrification by Mn/Al Catalysts,X773
  16. Investigation into ZnO Thin Film Transistors Prepared by Sol-gel Method,TN321.5
  17. Polyaniline and carbonaceous material / Polyaniline Composite Electrochemical Properties of,TB383.1
  18. Carbon nanotubes doped polyaniline and its application in gas sensors,TB383.1
  19. Composite Supercapacitor Electrode Materials Preparation and Properties,TM53
  20. Sol - gel method p -type ZnO films,O484.1
  21. Storage-stable organic / inorganic hybrid polymers and their light-cured coating application,TQ630.4

CLC: > Industrial Technology > Electrotechnical > Electrical materials > Magnetic materials,ferrite > Ferrite,oxide magnetic materials
© 2012 www.DissertationTopic.Net  Mobile