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Evaluation of Magnetic and Microwave Absorption Properties of Sr-Hexaferrite Nano Particles Doped With Zn and Ti

Baniasadi, Amin Reza | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43721 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Nemati, Ali; Ghasemi, Ali
  7. Abstract:
  8. In this study, the micro and nano particles of substituted strontium hexaferrites with nominal composition of SrFe12-xTix/2Znx/2O19 (x=0, 0.5, 1, 1.5, 2 and 2.5) were prepared by a co-precipitaion method. Ferrite-PVA composites (70:30) with thickness of 1.8mm were prepared at 220°C and 50Mpa. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were employed for characterization of synthesized powders and composites. XRD and FTIR results showed that single phase hexaferrite were obtained for almost all of the samples. Absorption peaks from 400cm-1 to 800cm-1 in the FTIR spectra correspond to stretching vibration of metal-oxygen in hexaferrites. According to the FE-SEM micrographs, the particle size of strontium ferrite powders calcined at 1200°C were 1-3μm, while the particle size of powders calcined at 900°C ranged from 100 to 200nm which were reduced to 30-50nm after milling by SPEX. Increasing the amount of dopant as a function of x was proved by EDS analysis. Coercivity of the micron size powders were decreased from 2220 (x=0) to 195Oe (x=2.5) by increasing the amount of Zn and Ti cations in the structure of hexaferrite. Increasing the x from 0 to 2.5 at nano size powders caused to reduce the saturation magnetization from 56 to 16emu/g and the lowest achieved coercivity was 88Oe. Substitution of Zn and Ti cations caused to drop the resonance frequency into the region of 12-18GHz, and the reflection loss for micron and nano size particles containing the highes amount of dopants were enhanced to -36.58 and -36.13dB, respectively
  9. Keywords:
  10. Co-Precipitation ; Coercivity Force ; Strontium Hexaferrite ; Saturation Magnetization ; Reflection Loss ; Ferromagnetic Resonance

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