Рубрики:
Hematite nanoparticles
NiO nanoparticles
Porous-glass
Ferritin
Particles
Temperature
Hysteresis
Transition
Anomalies
Mossbauer
Кл.слова (ненормированные):
Ferrihydrite -- Nanoparticles -- Superparamagnetism
Hematite nanoparticles
NiO nanoparticles
Porous-glass
Ferritin
Particles
Temperature
Hysteresis
Transition
Anomalies
Mossbauer
Кл.слова (ненормированные):
Ferrihydrite -- Nanoparticles -- Superparamagnetism
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 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit 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 KV≈1.7×105 erg/cm3 and KS≈0.055 erg/cm2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed.
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Держатели документа:
Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, Russian Federation
Siberian Federal University, Krasnoyarsk, Russian Federation
Presidium of Krasnoyarsk Scientific Center, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, Russian Federation
International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, Wroclaw, Poland
Доп.точки доступа:
Balaev, D. A.; Балаев, Дмитрий Александрович; Krasikov, A. A.; Красиков, Александр Александрович; Dubrovskiy, A. A.; Дубровский, Андрей Александрович; Popkov, S. I.; Попков, Сергей Иванович; Stolyar, S. V.; Столяр, Сергей Викторович; Bayukov, O. A.; Баюков, Олег Артемьевич; Iskhakov, R. S.; Исхаков, Рауф Садыкович; Ladygina, V. P.; Yaroslavtsev, R. N.