The magnetocaloric effect and heat capacity of ferrimagnetic nanosystems: High-dispersity magnetite

Korolev, V. V.; Aref'ev, I. M.; Ramazanova, A. G.

doi:10.1134/s0036024407060192

Cited by 3 publications

(9 citation statements)

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“…The magnetic field dependences of the thermodynamic parameters of solid particles, namely the specific heat capacity, enthalpy changing and changing the magnetic component of the molar heat capacity and entropy were determined. Well characterized (2,3,7,8,12,13,17,18-octaethylporphynato)chloromanganese(III) (Cl)MnOEP was chosen as an object.…”

Section: Introductionmentioning

confidence: 99%

Regularities of Magnetocaloric Effect and Determination of Some Thermodynamic Parameters for (Octaethylporphynato)chloro-manganese(III)

Korolev¹,

Klyueva²,

Arefyev³

et al. 2008

MHC

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chloromanganese(III) (6% suspension in water) were measured by microcalorimetric method in the dependence of temperature (298-353 K) and magnetic field (0-0.7 T). It is found that the MCE has positive value which increases with growth of the magnetic field induction at all the temperatures and decreases with the temperature growth at all the magnetic fields. Breaking the magnetic field leads to adiabatic demagnetizing. The dependence of specific heat capacity of the studied system from the value of magnetic field induction has maximum at 0.2-0.3 T at all the temperatures. When the induction value is higher than 0.6 T the specific heat capacity value is less than that in zero field. The temperature growth leads to the increase of the specific heat capacity in all the magnetic fields. On the base of the experimental data on the magnetocaloric effect and specific heat capacity of the manganese complex the dependencies of enthalpy, of the magnetic components of molar heat capacity and entropy from the temperature and magnetic induction are calculated.

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Section: Introductionmentioning

confidence: 99%

Regularities of Magnetocaloric Effect and Determination of Some Thermodynamic Parameters for (Octaethylporphynato)chloro-manganese(III)

Korolev¹,

Klyueva²,

Arefyev³

et al. 2008

MHC

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“…In this work, we continue our studies by determin ing the magnetocaloric effect, heat capacity, and enthalpy and entropy of magnetization for the high spin (acetato) (2,3,7,8,12,13,17,18 octa para tert butylphenyltetraazaporphynato)manganese(III) com plex at 298 K, R = p t BuPh; (AcO)Mn(p t BuPh) 8 8 TAP was prepared by cyclic tetramerization of bis(o tert butylphenyl)fumaronitrile in the presence of a manganese salt. Bis(para tert butylphenyl)fuma ronitrile (1 g, 2.91 mmol) and Mn(OAc) 2 · 4H 2 O (0.85 g, 3.48 mmol) were gradually heated to 423 K in 2 dimethylaminoethanol (7 mL) under stirring and held for 10 h. The consumption of nitrile was moni tored using thin layer chromatography (TLC).…”

Section: Introductionmentioning

confidence: 82%

“…The appearance of MCE in high spin porphyrin complexes was for the first time observed in [5] for the example of (2,3,7,8,12,13,17,18 octaethylpor phynato)chloromanganese(III) (Cl)MnOEP. In [6], an attempt was made to study the influence of the structure of the mixed five coordinate node in com plexes with 5,10,15,20 tetraphenylporphin having the general formula (X) n -2 TPP, where X -and TPP 2-are the acido and porphyrin ligands, respectively, on MCE and other magnetothermal properties.…”

Section: Introductionmentioning

confidence: 86%

“…Interest in MCE is related to the possibility of obtaining information about the nature of the magneti cally ordered state. When a magnetic field is applied to a magnet, the heat capacity also changes, and the heat capacity is the most important parameter necessary for calculations of many thermodynamic values, such as, for instance, magnetic entropy [2][3][4]. Magnetic entropy data also allow us to draw conclusions about magnetic ordering in magnetoactive substances.…”

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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The magnetothermal properties of substituted (tetraazoporphynato)manganese(III) in aqueous suspension

Korolev

Aref'ev

Ломова

et al. 2012

Russ. J. Phys. Chem.

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The magnetocaloric effect (MCE), heat capacity, and enthalpy and entropy of magnetization of the high spin (acetato) (2,3,7,8,12,13,17,18 octa para tert butylphenyltetraazaporphynato)manganese(III) complex in a 6% aqueous suspension were determined microcalorimetrically at 298 K in magnetic fields of 0.1-1.0 T, that is, under the conditions comparable with those used with (2,3,7,8,12,13,17,18 octaethylpor phynato)chloromagnanese(III) studied earlier. High dispersity complex particles were found to have para magnetic properties. Positive MCE values were obtained. These values grew as magnetic field induction increased. MCE sensitivity to the nature and electronic structure of the aromatic macroring was studied. The presence of aza groups in the structure of the complex decreases the MCE value compared with the porphyrin complex. The specific heat capacity of the complex strongly depended on the magnetic field value; field dependences had a maximum close to 0.3 T. Changes in the ΔS m (H, T) molar entropy part were also extremal and had maxima at 0.3-0.4 T. Prospects for the use of magnetothermal properties in the quantitative deter mination of thermodynamic characteristics and for revealing trends of changes in the magnetic activity of porphyrin complexes are discussed.

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Economic and Accessible Portable Homemade Magnetic Hyperthermia System: Influence of the Shape, Characteristics and Type of Nanoparticles in Its Effectiveness

Castelo-Grande,

Augusto,

Gomes

et al. 2024

Materials

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Currently, one of the main causes of death in the world is cancer; therefore, it is urgent to obtain a precocious diagnosis, as well as boost research and development of new potential treatments, which should be more efficient and much less invasive for the patient. Magnetic hyperthermia (MH) is an emerging cancer therapy using nanoparticles, which has proved to be effective when combined with chemotherapy, radiotherapy and/or surgery, or even by itself, depending on the type and location of the tumor’s cells. This article presents the results obtained by using a previously developed economic homemade hyperthermia device with different types of magnetite nanoparticles, with sizes ranging between 12 ± 5 and 36 ± 11 nm and presenting different shapes (spherical and cubic particles). These magnetic nanoparticles (MNPs) were synthesized by three different methods (co-precipitation, solvothermal and hydrothermal processes), with their final form being naked, or possessing different kinds of covering layers (polyethylene glycol (PEG) or citric acid (CA)). The parameters used to characterize the heating by magnetic hyperthermia, namely the Specific Absorption Rate (SAR) and the intrinsic loss power (ILP), have been obtained by two different methods. Among other results, these experiments allowed for the determination of which synthesized MNPs showed the best performance concerning hyperthermia. From the results, it may be concluded that, as expected, the shape of MNPs is an important factor, as well as the time that the MNPs can remain suspended in solution (which is directly related to the concentration and covering layer of the MNPs). The MNPs that gave the best results in terms of the SAR were the cubic particles covered with PEG, while in terms of total heating the spherical particles covered with citric acid proved to be better.

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The magnetocaloric effect and heat capacity of ferrimagnetic nanosystems: High-dispersity magnetite

Cited by 3 publications

References 1 publication

Regularities of Magnetocaloric Effect and Determination of Some Thermodynamic Parameters for (Octaethylporphynato)chloro-manganese(III)

Regularities of Magnetocaloric Effect and Determination of Some Thermodynamic Parameters for (Octaethylporphynato)chloro-manganese(III)

The magnetothermal properties of substituted (tetraazoporphynato)manganese(III) in aqueous suspension

Economic and Accessible Portable Homemade Magnetic Hyperthermia System: Influence of the Shape, Characteristics and Type of Nanoparticles in Its Effectiveness

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