Abstract
Fe-doped La0.77Sr0.23Mn1 − yFeyO3 nanoparticles have been synthesized by sol-gel method, and ceramic samples based on them were sintered at 1613 K. Crystallographic and magnetic properties of obtained nanoparticles and ceramic samples have been studied. It has been established that cell volume for nanoparticles increases with growing of iron content, while this dependence displays an opposite trend in the case of ceramic samples. Mössbauer investigations have shown that in all samples, the oxidation state of iron is +3. According to magnetic studies, at room temperature, both nanoparticles and ceramic samples with y ≤ 0.06 display superparamagnetic properties and samples with y ≥ 0.08 are paramagnetic. Magnetic fluids based on La0.77Sr0.23Mn1 − yFeyO3 nanoparticles and aqua solution of agarose have been prepared. It has been established that heating efficiency of nanoparticles under an alternating magnetic field decreases with growing of iron content.
Highlights
Nanoparticles and composite materials based on them have unique electrical, chemical, and magnetic properties
Iron-doped manganite nanoparticles were synthesized by sol-gel method
As seen from the table, the unit cell volume of the nanoparticles increases with growing of iron content
Summary
Nanoparticles and composite materials based on them have unique electrical, chemical, and magnetic properties. One of the most promising directions of magnetic nanoparticle investigations is the opportunity to use them in engineering, medicine, and biology, for creation of new magnetic recording systems, for biological fluid purification, for drug and gene delivery, and for hyperthermia [4,5,6]. Mössbauer investigations show that Fe3O4 nanoparticles are non-stable: Fe2+ partially oxidizes to Fe3+, and this leads to creation of maghemite (γ-Fe2O3) phase [10]. One more essential drawback of magnetite is the fact that the transition temperature from magnetically ordered to non-magnetic state (Curie temperature) is quite high: TC = 585 °C [11]. Since magnetic-field-induced heating is only operative in magnetically ordered state [3], high Curie temperature may give rise to uncontrolled and non-uniform heating of tumors to high temperatures, which, in turn, may lead to destroying the healthy tissues
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