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Title:Magnetni nanodelci na osnovi zlitin NiCu in NiCr za uporabo v samoregulativni magnetni hipertermiji
Authors:ID Stergar, Janja (Author)
ID Ban, Irena (Mentor) More about this mentor... New window
Files:.pdf DR_Stergar_Janja_2014.pdf (3,53 MB)
MD5: F3FA1D14A62BF76D99E032EBB5D00029
 
Language:Slovenian
Work type:Dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:V doktorskem delu smo obravnavali sintezo in karakterizacijo nanodelcev zlitin NiCu in NiCr za uporabo v samoregulativni magnetni hipertermiji. V prvem delu smo pripravili zlitine NiCu in NiCr s tremi različnimi sinteznimi postopki: mehansko mletje, sinteza s pomočjo mikroemulzij in sol-gel metoda, pri čemer smo preučevali reakcijske pogoje posamezne sinteze. Sledila je karakterizacija pridobljenih zlitin s pomočjo rentgenske praškovne difrakcije, transmisijske elektronske mikroskopije, magnetnih meritev, meritev Curiejeve temperature in kalorimetričnih meritev. S pomočjo mehanskega mletja smo uspeli sintetizirati zlitine NiCu in NiCr, z različnimi sestavami, v inertni atmosferi dušika. Kot rezultat smo dobili superparamagnetne nanodelce, njihova ocenjena velikost je okrog 14 nm za NiCu in 11 nm za NiCr. Pomerjene vrednosti Curiejevih temperatur rastejo z naraščanjem vsebnosti niklja. Vzorca sestave Ni72Cr28 in Ni72.5Cu27.5 imata Curiejevo temperaturo, ki je v območju od 42 °C do 46 °C, kar ustreza uporabi v magnetni hipertermiji. Pod vplivom zunanjega izmeničnega magnetnega polja se delci zelo dobro odzivajo. Dosežene stacionarne temperature so prav tako v območju uporabe v magnetni hipertermiji. S pomočjo transmisijske elektronske mikroskopije smo ugotovili, da je porazdelitev velikosti delcev široka, da so sintetizirani nanodelci sestavljeni iz večjih agregatov, da so nehomogeni, kar pripisujemo posledicam mehanskega mletja. S pomočjo mikroemulzijske metode smo sintetizirali nanodelce zlitin NiCr in NiCu, ti imajo ožjo porazdelitev velikosti, vendar pa so nehomogeni, saj so oksidacijski potenciali kovin različni in dobimo tako imenovano "core-shell" strukturo. Homogenizacija pri zlitinah NiCr ni bila uspešna, medtem ko smo zlitine NiCu uspeli ustrezno prevleči z 10 nm plastjo silike oziroma smo jih vgradili v matrici NaCl, da smo preprečili aglomeracijo med samo homogenizacijo. Homogenizacija pri zlitinah NiCu je bila uspešna, kar kaže Curiejeva temperatura. Specifična magnetizacija za oblečene delce je veliko manjša kot za neoblečene, kar je posledica diamagnetne prevleke SiO2, vendar pa lahko to prevleko poljubno tanjšamo oziroma odstranimo s pomočjo raztopine NaOH, prav tako lahko odstranimo tudi matrico NaCl. Vzorcem smo določili še specifično absorpcijsko hitrost (SAR), ki narašča z naraščajočim magnetnim poljem. Sol-gel metoda se je izkazala kot najuspešnejša za sintezo zlitin NiCu z različnimi sestavami, saj smo kot rezultat dobili okrogle monodisperzne nanodelce. Pripravili smo homogene zmesi kovinskih oksidov v SiO2 matrici s kalcinacijo prekurzorjev v gelu in naknadno homogenizacijo in redukcijo produkta v cevni peči v inertni atmosferi Ar/H2. Velikost delcev, ocenili smo jo s pomočjo Sherrerjeve formule, magnetnih meritev in s pomočjo transmisijske elektronske mikroskopije, je znašala okrog 16 nm. S pomočjo raztopine NaOH in hidrazina smo SiO2 uspešno izlužili. Curiejeve temperature vzorcev naraščajo z naraščajočo vsebnostjo niklja in so v okviru predvidenih temperatur za uporabo v magnetni hipertermiji. Tudi vrednosti magnetizacije in temperaturni odziv v kalorimetru rasteta z naraščajočo vsebnostjo niklja.
Keywords:magnetni nanodelci, Curiejeva temperatura, magnetna hipertermija, mehansko mletje, mikroemulzijska metoda, sol-gel metoda, silika, magnetna tekočina
Place of publishing:Maribor
Publisher:[J. Stergar]
Year of publishing:2014
PID:20.500.12556/DKUM-44058 New window
UDC:666.9-12:676.017.5(043.3)
COBISS.SI-ID:17808918 New window
NUK URN:URN:SI:UM:DK:QNTFGTV2
Publication date in DKUM:09.05.2014
Views:2871
Downloads:351
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
:
STERGAR, Janja, 2014, Magnetni nanodelci na osnovi zlitin NiCu in NiCr za uporabo v samoregulativni magnetni hipertermiji [online]. Doctoral dissertation. Maribor : J. Stergar. [Accessed 2 April 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=44058
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Secondary language

Language:English
Title:Magnetic nanoparticles of NiCu and NiCr alloys for self-regulating magnetic hyperthermia
Abstract:The doctoral thesis considers the synthesis and characterization of NiCu and NiCr nanoparticles for the magnetic hyperthermia applications. The synthesis of nanoparticles of NiCu and NiCr alloys using three different methods: mechanical milling, microemulsion method and sol-gel method, were studied with respect to the reaction conditions. We characterized the alloys nanoparticles by XRD measurements, transmission electron microscopy, magnetic measurements, Curie temperature determination and calorimetric measurements. The NiCu and NiCr particles with the desired composition were synthesized by mechanical milling under an inert atmosphere of N2. We prepared superparamagnetic NiCu nanoparticles with an average size of around 14 nm and around 11 nm for NiCr. The measurements of the Curie temperature of various compositions showed that the Curie temperature increased with the increasing of the Ni content. The nanoparticles of Ni72.5Cu27.5 and Ni72Cr28 exhibit a Curie temperature in the range between 42 °C to 46 °C, what corresponds to the application demand in the magnetic hyperthermia. The magnetic particles also showed a significant heating effect and might be the good candidates for hyperthermia applications. Transmission electron microscopy of mechano-chemically synthesized particles showed a broad size distribution with the presence of some larger grains in the shape of platelets at some locations. NiCu and NiCr nanoalloys with a narrow size distribution were synthesized by microemulsion method. The Curie temperatures of samples were high, indicating a compositional heterogeneity and probably a “core-shell” structure. To prevent the agglomeration during the homogenization of the NiCu alloys, we coated particles with a 10 nm thick layer of silica or we performed thermally homogenization in a NaCl matrix. The relatively low magnetization of the silica coated NiCu particles was a result of the diamagnetic envelope of SiO2, which can be thinned and/or remowed with sodium hydroxide. In parallel the NaCl matrix can be removed with dissolution in water. The calculated specific absorption rate (SAR) increases with the increasing of the magnetic field. Nickel-copper (NiCu) alloy magnetic nanoparticles with a narrow size distribution were prepared by a sol-gel method. We used the temperature resistant silica matrix as a nanoparticles holder during high-temperature treatment of metal oxides and a specially developed etching procedure that subsequently removes silica matrix, leaving the alloy nanoparticles intact. We estimated the size of the particles around 16 nm, using the Sherrer equation, magnetic measurements and transmission electron microscopy. The Curie temperature, the magnetization and the temperature response in the calorimeter increase as well with the increase of the Ni content.
Keywords:magnetic nanoparticles, Curie temperature, magnetic hyperthermia, mechanical milling, microemulsion method, sol-gel method, silica coating, magnetic fluids


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