Synthesis and Physical Properties of MO·Fe12O18 (M/Ba and Sr) Nanoparticles Prepared by Sol-Gel Method Using Propylene Oxide

Propylene Oxide를 이용한 졸-겔법에 의한 MO·Fe12O18 (M/Ba, Sr) 나노 분말의 합성과 물리적 특성

  • Lee, Su Jin (Department of Chemical System Engineering, Keimyung University) ;
  • Choe, Seok Burm (Department of Chemical System Engineering, Keimyung University) ;
  • Gwak, Hyung Sub (Department of Chemical System Engineering, Keimyung University) ;
  • Paik, Seunguk (Department of Chemical System Engineering, Keimyung University)
  • 이수진 (계명대학교 화학시스템공학과) ;
  • 최석범 (계명대학교 화학시스템공학과) ;
  • 곽형섭 (계명대학교 화학시스템공학과) ;
  • 백승욱 (계명대학교 화학시스템공학과)
  • Received : 2006.06.09
  • Accepted : 2006.07.27
  • Published : 2006.08.10


Nano sized mixed metal hexagonal ferrite powders with improved magnetic properties have been prepared by sol-gel method using propylene oxide as a gelation agent. To obtain the desired ferrite, two different metal ions were used. One of the ions has only +2 formal charge. The key step in the processes is that hydrated $Ba^{2+}$ or $Sr^{2+}$ ions are hydrolyzed and condensed at the surface of the previously formed $Fe_{2}O_{3}$ gel. In this processes, all the reaction can be finished within a few minutes. The magnetic properties of the produced powder were improved by heat treatment. The highest values of the magnetic properties were achieved at temperature $150^{\circ}C$ lower than those of the previously published values. The highest observed values of coercivity and the saturation magnetization of Sr-ferrite and Ba-ferrite powder were 6198 Oe, 5155 Oe and 74.4 emu/g, 68.1 emu/g, respectively. The ferrite powder annealed at $700^{\circ}C$ showed spherical particle shapes. The resulting spheres which were formed by the aggregation of nanoparticles with size 3~5 nm have diameter around 50 nm. The powder treated at $800^{\circ}C$ showed hexagonal-shaped grains with crystallite size above 500 nm.


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