6 research outputs found
Synthesis, morphology, microstructure and magnetic properties of hematite nanoparticles
Predmet ovog rada je usmeren na istraÅ£ivanja nanoÄestiÄnog hematita (Ī±-Fe2O3). U ovom radu su ispitivana tri uzorka. Cilj istraÅ£ivanja bio je da se dobiju uzorci nanoÄestiÄnog hematita sa velikom jaÄinom koercitivnog polja na sobnoj temperaturi.
Prvi uzorak Ī±-Fe2O3(SC) sintetisan je metodom vodenog sagorevanja, sa ureom kao gorivom. Dobijena je visoka koncentracija nanoÄestica hematita u amorfnoj matrici aluminijum oksida i neobiÄna sunÄerasta morfologija. Ove Äestice porozne strukture pogodne su za primenu u medicini, tj. kao prenosioci lekova na odreÄene lokalitete u organizmu, pri Äemu se lekovi smeÅ”taju u pore amorfne matrice aluminijum oksida. Drugi uzorak Ī±-Fe2O3(HDT) pokazuje efekat anizotropije oblika, Å”to utiÄe na magnetne osobine, posebno na poveÄanje jaÄine koercitivnog polja. Morfologija ploÄica moÅ£e poboljÅ”ati magnetna svojstva nanomaterijala, Å”to moÅ£e imati veliki znaÄaj u fundamentalnim istraÅ£ivanjima i u tehnoloÅ”kim primenama. TreÄi uzorak Ī±-Fe2O3(TD), superstrukture sliÄne naru, ima izrazito veliku jaÄinu koercitivnog polja na sobnoj temperaturi, koja je meÄu najviÅ”im za nanoÄestiÄni hematit. Dobijena vrednost jaÄine koercitivnog polja za Ī±-Fe2O3(TD) na sobnoj temperaturi u ovom radu (HC = 4350 Oe) je oko 30 puta veÄa od jaÄine koercitivnog polja sfernih Äestica. Sem toga, jaÄina koercitivnog polja je mnogo viÅ”a nego jaÄina koercitivnog polja balk hematita (HC = 1670 Oe). Ova ogromna razlika i velika vrednost jaÄine koercitivnog polja trebalo bi da bude pripisana novoj, jedinstvenoj, superstrukturi nanoÄestica, sliÄnoj naru. Nove magnetne osobine ove hematitne superstrukture potiÄu od unutraÅ”nje mikrostrukture i jakih meÄuÄestiÄnih interakcija izmeÄu nanokristalnih subjedinica. Dobijena velika vrednost za jaÄinu koercitivnog polja je dobra osnova za dalja istraÅ£ivanja nanoÄestiÄnih materijala. IstraÅ£ivanje novih svojstava hematitnih superstruktura biÄe predmet daljeg rada.
NanoÄestiÄni hematit Ī±-Fe2O3 pokazuje Å”irok spektar vrednosti magnetnih karakteristika i on je predmet intenzivnog nauÄnog, tehniÄkog i tehnoloÅ”kog prouÄavanja poslednjih Å”esdeset godina. Za nanoÄestiÄni hematit posebno su vaÅ£ne njegove magnetne karakteristike, koje se mogu podeÅ”avanjem veliÄine, morfologije i mikrostrukture Äestica menjati u Å”irokom opsegu vrednosti razliÄitim sintezama i kontrolisanjem odreÄenih parametara u postupku sinteze. Hematit je najstabilniji oksid gvoÅ£Äa sa visokom otpornoÅ”Äu na koroziju, biokompatibilan je i netoksiÄan. NanoÄestiÄni hematit se pokazao kao veoma pogodan materijal za razne primene: kao medijum za magnetni zapis, pigment, katalizator u reakcijama za oksidaciju alkohola, aldehida i ketona, za gasne senzore, litijum - jonske baterije, fotoelektrode i biomedicinske primene.The subject of this work is research of nanoparticle hematite (Ī±-Fe2O3). Three samples of hematite nanoparticles have been researched in this work. The aim of the research was obtaining samples of nanoparticle hematite with high intensity of coercivity at room temperature.
The first sample of nanosized Ī±-Fe2O3(SC) was synthesized by water combustion process using urea as a fuel. High concentration of nanoparticle hematite in amorphous alumina matrix and uncommon sponge-like morphology has been obtained. These particles with porous structure are suitable for medical applications as drug carriers. The second sample of nanosized Ī±-Fe2O3(HDT) shows shape anisotropy effect which influences magnetic properties, especially increase in coercivity. Plate-like morphology can improve magnetic properties of nanosized hematite which could be of great significance in fundamental researches and technological implementations. The third sample of nanosized Ī±-Fe2O3(TD) with pomegranate-like superstructure has high room temperature coercivity, among the highest for nanosized hematite. Room temperature coercivity of Ī±-Fe2O3(TD), obtained in this work (HC = 4350 Oe), is about thirty times higher than coercivity of spherical nanoparticles. Besides, the obtained coercivity is much higher than coercivity of bulk hematite (HC = 1670 Oe). This great difference and high coercivity should be attributed to new, unique pomegranate-like nanoparticle superstructures. New magnetic properties of this hematite superstructure originate from internal microstructure and strong interactions between nanocrystalline subunits. The obtained high coercivity is a good foundation for future research of nanosized materials. Research of new hematite superstructures properties will be the subject of future studies.
Nanosized hematite Ī±-Fe2O3 shows wide range of magnetic properties. Therefore, it has been the subject of intensive scientific, technical and technological research last sixty years. Magnetic properties of nanoparticle hematite are particularly important. Adjusting the size, the morphology and the microstructure, they can be changed in wide range of value by different syntheses and control of certain parameters during the synthesis process. Hematite is the most stable oxide of iron with high corrosion resistance; moreover it is non-toxic and biocompatible. Nanosized hematite proved to be very good material for different applications, such as magnetic recording medium, pigment, catalytic converter in chemical reactions of alcohol, aldehyde and ketone oxidation, gas sensors, lithium - ion batteries, photo electrodes and biomedical applications
Synthesis, diffraction experiments, transmission electron microscopy and magnetic properties of Ī±-Fe2O3/SiO2 nanocomposite sample
Cilj rada bio je istraživanje magnetnih karakteristika nanoÄestiÄnog feri-oksida Ī±-Fe2O3 (hematita), u amorfnoj matrici silicijum-dioksida. Ispitivani uzorak nanokompozitnog feri-oksida dobijen je sol-gel metodom. Kristalna faza uzorka odreÄena je pomoÄu difrakcije elektrona i X-zraka. Na osnovu TEM (transmisiona elektronska mikroskopija) snimaka utvrÄena je veliÄina Äestica. Ispitivanja magnetnih osobina uzorka obuhvatila su merenja DC magnetizacije i AC susceptibilnosti u opsegu temperatura od 2 K do 300 K i magnetnih polja od -5 T do 5 T. Merenja su uraÄena na SQUID magnetometru. Cilj je bio da se pokaže da je sol-gel metoda pogodna za sintezu nanoÄestiÄnog hematita i da se potvrdi nanoÄestiÄno ponaÅ”anje ispitivanog uzorka. UtvrÄeno je postojanje meÄuÄestiÄnih interakcija, kao i uticaj Å”irine distribucije nanoÄestica na magnetne karakteristike nanokompozitnog uzorka Ī±-Fe2O3. Magnetne karakteristike uzorka poreÄene su sa magnetnim karakteristikama drugih uzoraka nanoÄestiÄnog hematita i ukazano je na moguÄnosti njegove primene
Sol-gel synthesis and magnetic properties of hematite (Ī±-Fe2O3) nanoparticles
U radu je prikazano istraživanje magnetnih karakteristika nanoÄestiÄnog feri-oksida, Ī±-Fe2O3 (hematita), koji ispoljava superparamagnetne karakteristike tj. superparamagnetizam. Prikazano je nanoÄestiÄno ponaÅ”anje uzoraka, uporeÄene su karakteristike nanoÄestiÄnog materijala sa materijalom visokog kristaliniteta i prikazan je uticaj veliÄine nanoÄestica na magnetne karakteristik
About the first experiment at JINR nuclotron deuteron beam with energy 2.52 gev on investigation of transmutation of I-129, NP-237, PU-238 and PU-239 in the field of neutrons generated in pbtarget with U-blanket
The experiment described in this communication is a part of the scientific program āInvestigations of physical aspects of electronuclear method of energy production and transmutation of radioactive waste of atomic energetic using relativistic beams from the JINR Synchrophasotron/Nuclotronā - the project āEnergy plus Transmutationā. The performing of the first experiment at deuteron beam with energy 2.52 GeV at the electronuclear setup which consists of Pb-target with U-blanket (206.4 kg of natural uranium) and transmutation samples and its preliminary results are described. The hermetic samples of isotopes of I-129, Np-237, Pu-238 and Pu-239 which are produced in atomic reactors and industry setups which use nuclear materials and nuclear technologies were irradiated in the field of electronuclear neutrons produced in the Pbtarget surrounded with the U-blanket setup āEnergy plus transmutationā. The estimations of its transmutations (radioecological aspect) were obtained in result of measurements of gamma activities of these samples. The information about space-energy distribution of neutrons in the volume of the Pb-target and the U-blanket was obtained with help of sets of activation threshold detectors (Al, V, Cu, Co, Y, In, I, Ta, Au, W, Bi and other), solid state nuclear track detectors, He-3 neutron detectors and nuclear emulsions
Synthesis, diffraction experiments, transmission electron microscopy and magnetic properties of Ī±-Fe2O3/SiO2 nanocomposite sample
Cilj rada bio je istraživanje magnetnih karakteristika nanoÄestiÄnog feriāoksida Ī±-Fe2O3 (hematita), u amorfnoj matrici silicijum-dioksida. Ispitivani uzorak nanokompozitnog feri-oksida dobijen je sol-gel metodom. Kristalna faza uzorka odreÄena je pomoÄu difrakcije elektrona i Xāzraka. Na osnovu TEM (transmisiona elektronska mikroskopija) snimaka utvrÄena je veliÄina Äestica. Ispitivanja magnetnih osobina uzorka obuhvatila su merenja DC magnetizacije i AC susceptibilnosti u opsegu temperatura od 2Ā K do 300Ā K i magnetnih polja od -5 T do 5 T. Merenja su uraÄena na SQUID magnetometru. Cilj je bio da se pokaže da je sol-gel metoda pogodna za sintezu nanoÄestiÄnog hematita i da se potvrdi nanoÄestiÄno ponaÅ”anje ispitivanog uzorka. UtvrÄeno je postojanje meÄuÄestiÄnih interakcija, kao i uticaj Å”irine distribucije nanoÄestica na magnetne karakteristike nanokompozitnog uzorka Ī±āFe2O3. Magnetne karakteristike uzorka poreÄene su sa magnetnim karakteristikama drugih uzoraka nanoÄestiÄnog hematita i ukazano je na moguÄnosti njegove primene.</p
Mechanochemical synthesis and magnetic properties of maghemite
This work presents the results of an investigation on maghemite (Ī³ -Fe2O3) nanoparticles magnetic properties, which show superparamagnetic behavior i.e. superparamagnetism. Nanoscale maghemite samples were obtained by the mechanochemical method. The crystal structure of the samples was analyzed by the electron diffraction and the X-ray powder diffraction. The formation of monophase maghemite was shown. The particle size was determined by the transmission electron microscopy (TEM). The shift of the blockage temperature TB towards lower values with increasing field strength is significant, which is the indication of the superparamagnetism in the system under consideration