Iron-Doped (La,Sr)MnO3 Manganites as Promising Mediators of Self-Controlled Magnetic Nanohyperthermia

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.

Manganite Nanoparticles as Promising Heat Mediators for Magnetic Hyperthermia: Comparison of Different Chemical Substitutions

“…According to XRD investigations, all samples are single-phase and crystallize in the distorted perovskite structure. The average nanoparticle sizes lie in the range 25-35 nm for the Fe-substituted series [17] and 31-38 nm for the Sm-substituted one [18].…”

“…Magnetic properties of the samples of both series were reported in Refs. [17,18]. It was shown that both kinds of substitutions (Mn → Fe and La → Sm) give rise to the decrease of room-temperature magnetization and the Curie temperature T C .…”

“…It was shown in Ref. [17] that temperature behavior of nanoparticles ensemble can be satisfactory described by the introduction of an average Curie temperature T C concept. It is expected in this case that the behavior of the magnetization of nanoparticles ensemble will obey the law M (T ) ∼ √ T C − T .…”

“…Iron-and samarium-substituted manganite nanoparticles, La 0.77 Sr 0.23 Mn 1−x Fe x O 3 with x F e = 0, 0.02, 0.04, 0.06, and La 0.7−x Sm x Sr 0.3 MnO 3 with x Sm = 0, 0.01, 0.04, 0.06, 0.08, respectively, were synthesized via solgel method [17,18]. Water-soluble salts La(NO 3 ) 3 , Sm(NO 3 ) 3 , Sr(NO 3 ) 2 , Mn(NO 3 ) 2 and Fe(NO 3 ) 3 were used as starting reagents.…”

Effect of Synthesis Temperature on Structure and Magnetic Properties of (La,Nd)0.7Sr0.3MnO3 Nanoparticles

“…Their Curie temperature strongly depends on the chemical composition: it demonstrates the maximal value at y  ≈ 0.3 ( T C max  ≈ 370 K) and quite sharply decreases as y deviates from 0.3. Earlier, it was shown that fine controlling of the Curie point within the narrow temperature range can be reached by low-level substitutions in manganese sublattice [22]. At the same time, partial substitutions of La 3+ ions by other rare-earth ions (for instance, by Nd 3+ ) may be one more possible way of fine-tuning the phase-transition temperature, since magnetic interactions in manganites are sensitive to the lattice parameters and strength of local lattice distortions [23].…”