Magnetic properties of heat treated bacterial ferrihydrite nanoparticles

Описание

Тип публикации: статья из журнала

Год издания: 2016

Идентификатор DOI: 10.1016/j.jmmm.2016.02.059

Ключевые слова: Ferrihydrite, Nanoparticles, Superparamagnetism, Anisotropy, Bacteria, Distribution functions, Heat treatment, Low temperature operations, Magnetic anisotropy, Magnetic materials, Magnetic moments, Magnetism, Magnetic properties, Temperature, Antiferromagnetics, Average magnetic moments, Blocking temperature, Ferrihydrites, Magnetic anisotropy constant, Low temperatures, Magnetization curves, Superparamagnetic behavior, Nanomagnetics

Аннотация: The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 degrees C) heat treatment for up to 240 h. The bacterial ferrihydrite particles eПоказать полностьюxhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants K-v approximate to 1.7 x 10(5) erg/cm(3) and K-s approximate to 0.055 erg/cm(2) have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed. (C) 2016 Elsevier B.V. All rights reserved.

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Издание

Журнал: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Выпуск журнала: Vol. 410

Номера страниц: 171-180

ISSN журнала: 03048853

Место издания: AMSTERDAM

Издатель: ELSEVIER SCIENCE BV

Авторы

  • Balaev D.A. (Siberian Federal University)
  • Krasikov A.A. (Siberian Federal University)
  • Dubrovskiy A.A. (International Laboratory of High Magnetic Fields and Low Temperatures)
  • Popkov S.I. (Siberian Federal University)
  • Stolyar S.V. (Siberian Federal University)
  • Bayukov O.A. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Iskhakov R.S. (Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch)
  • Ladygina V.P. (Presidium of Krasnoyarsk Scientific Center, Russian Academy of Sciences, Siberian Branch)
  • Yaroslavtsev R.N. (Siberian Federal University)

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