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Start Over Descriptor "*PARAMAGNETISM" Language serbian
3 results on '"*PARAMAGNETISM"'

1. SINTEZA, DIFRAKCIONI EKSPERIMENTI, TRANSMISIONA ELEKTRONSKA MIKROSKOPIJA I MAGNETNE OSOBINE NANOKOMPOZITNOG UZORKA α-Fe2O3/SiO2.

Author

Tadić, Marin M. and Čitaković, Nada M.

Subjects
*IRON ores, *MICROSCOPY, *DIFFRACTION patterns, *ELECTRONS, *OPTICS
Abstract

The sol-gel method was successfully utilized for the synthesis of the highly concentrated α-Fe2O3/SiO2 nanocomposite containing 45 wt% of hematite. TEM micrograph showed that spherical particles of 10 nm average size were evenly dissolved in glassy silica matrix. Both DC magnetization and AC susceptibility measurements indicated superparamagnetic behaviour of the system with the blocking temperature TB ≈ 65 K. Magnetization vs. field data at 300 K was successfully fitted to a weighted Langevin's curve for superparamagnetic system and the particle size obtained from this fit was in excellent agreement with the TEM results. Several features evinced in the magnetic data pointed to the presence of non-negligible magnetic interaction between hematite nanoparticles: the weak field dependence of the magnetization as a function of temperature, narrowing of the hysteresis loop at low applied field below TB, and high value of TB for hematite nanoparticles of 10 nm in size. On the other hand, features like continuous increase of the ZFC magnetization with decreasing temperature and the absence of a plateau or a peak in the FC branch showed that no strong magnetic interactions were present in the system.The AC susceptibility study showed that the Vogel-Fulcher model for singledomain inter-acting particles was applicable, while the empirical parameters C1 = 0,055 and C2 = 0,57 that lie between values for strongly interacting systems and non-interacting systems obtained have pointed to the presence of the interactions of intermediate strength. On the basis of the above listed results, we can conclude that the system under consideration consists of interacting single- domain hematite nanoparticles with magnetic properties that are located between weakly and strongly interacting systems. [ABSTRACT FROM AUTHOR]

Published
2014
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2. SINTEZA, DIFRAKCIONI EKSPERIMENTI, TRANSMISIONA ELEKTRONSKA MIKROSKOPIJA I MAGNETNE OSOBINE NANOKOMPOZITNOG UZORKA α-Fe2O3/SiO2.

Author

Tadić, Marin M. and Čitaković, Nada M.

Subjects
IRON ores, MICROSCOPY, DIFFRACTION patterns, ELECTRONS, OPTICS
Abstract

Copyright of Military Technical Courier / Vojnotehnicki Glasnik is the property of Military Technical Courier / Vojnotehnicki Glasnik and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2014
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3. Opto-magnetne karakteristike polimernih materijala za kontaktna sočiva sa različitim koncentracijama nanomaterijala

Author

Tomić, Marija M., Vasić Milovanović, Aleksandra, Matija, Lidija, Sedmak, Aleksandar, Lukić, Petar, and Stamenković, Dragomir

Subjects
silikon hidrogelovi, fullerene, fulerol, diamagnetism, fullerol, paramagnetism, opto-magnetna imidžing spektroskopija, silicon hydrogel, opto-magnetic imaging spectroscopy, paramagnetizam, remanentna magnetizacija, fuleren, dijamagnetizam, remanent magnetization
Abstract

Fulereni i njihovi derivati imaju značajnu osobinu da istovremeno poseduju i paramagnetna i dijamagnetna svojstva zahvalјujući rasporedu uglјenikovih atoma u petouglove i šestouglove. Kada se fulereni ili fuleroli nađu u polimernim materijalima njihova magnetna svojstva će uticati na magnetna svojstva polimera. Svrhа dodavanja fulеrоlа u smešu monomera pa zatim njihova pоlimеrizacija је modifikacija postojećih mаtеriјаlа zа mеkа kоntаktnа sоčivа sа pоbоlјšаnim оptičkim i mеhаničkim kаrаktеristikаmа. Оdrеđivаnjеm vrednosti rеmаnеntnе mаgnеtizаciје može sе sagledati uticај dodatog fulеrоlа na magnetne osobine polimernog materijala, а uz pоmоć оptо- mаgnеtnоg spеktrа sе mоgu оdrеditi pаrаmagnеtnа i diјаmаgnеtnа svојstvа mаtеriјаlа. Cilј је dа sе pоkаžu rаzlikе u mаgnеtnim оsоbinаmа mаtеriјаlа koje utiču na biološko tkivo prе i pоslе spоlјаšnjih uticаја rаzličitih vrstа svеtlоsti kао štо su: bеlа difuzna, bela pоlаrizоvаnа i ultrаlјubičаstа svеtlоst. Pored toga određen i je uticaj biološkog sistema (čoveka) na magnetne osobine materijala. Оčеkivаni rеzultаti bi pоkаzаli kаkо sе mеnjајu оptо-mаgnеtnа svојstvа nаnоfоtоničnih mаtеriјаlа pоd rаzličitim spоlјаšnjim uticајimа i kаkаv је uticај inkоrpоrirаnоg fulеrоlа u pоlimеrnе mаtеriјаlе. Materijali su sintеtisаni ugrаđivаnjеm fulеrоlа C60(OH)24 u kоmеrciјаlni materijal za mеkа kоntаktnа sоčivа (Definitive74 kоје је nаprаvilа kоmpаniја Contamac, Vеlikа Britаniја). Za ova istraživanja upotrebljene su tri rаzličitе kоncеntrаciје fulеrоlа: 0,003%, 0,010% i 0,015%. Nа tај nаčin su dоbiјеnа tri različita mаtеriјаlа zа mеkа kоntаktnа sоčivа, a čеtvrti mаtеriјаl, stаndаrdni, upоtrеblјеn je kао rеfеrеntni uzоrаk. Zа istrаživаnjа је kоrišćеn urеđај zа mеrеnjе rеmаnеntnе mаgnеtizаciје JR-6A kао i opto-magnetna imidžing spektroskopija (OMIS). Fullerene and its derivatives are specific for having both paramagnetic and diamagnetic properties since carbon atoms are structured into pentagons and hexagons. Fullerenes and fullerols in polymer materials affect magnetic properties of those materials. The purpose of incorporating fullerol into monomer compound and their polymerization was the modification of existing materials for soft contact lenses with improved optical and mechanical characteristics. By measuring remanent magnetization it is possible to establish the influence of added fullerol on magnetic properties of polymer material and by opto-magnetic spectrum it is possible to define paramagnetic and diamagnetic properties of materials. The goal is to show the deferences in magnetic properties of materials before and after external influences of different types of light sources: white, polarized and ultraviolet light because magnetic material has an influence on biological tissue. The influence of biological factor (human being) on magnetic properties of materials was measured as well. The results will show the changes of opto-magnetic properties of nanophotonic materials under different external influences and the affect of incorporated fullerol in polymer material. The materials are synthesized by incorporating fullerol C60(OH)24 into commercial material for soft contact lenses (Definitive74) made by Contamac, Great Britain. Three different concentrations are used: 0.003%, 0.01% i 0.015%. Three materials for soft contact lenses have been synthesized and the fourth one, the basic material, used as a reference sample. Spinner magnetometer JR-6A and Opto-magnetic imaging spectroscopy were used in this investigation.

Published
2016

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