248 KB23 KB200020242014Marinšek, MarjanStambolić, Alešštevilka:2letnik:48str. 275-280COBISSID:1045418ISSN:1580-2949URN:URN:NBN:SI:doc-N7FBI6VJenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijecobalt ferriteco-precipitationkobaltov feritkoprecipitacijamagnetene tekočinemagnetic fluidsmagnetitmagnetitesuperparamagnetic nanoparticlessuperparamagnetni nanodelciThe preparation of magnetic nanoparticles based on cobalt ferrite or magnetite| Priprava magnetnih nanodelcev na osnovi kobaltovega ferita ali magnetita|Cobalt ferrite and magnetite nanoparticles are superparamagnetic materials. Stable suspensions of superparamagnetic nanoparticles are magnetic fluids. Stable magnetic fluids are prepared by the addition of surfactants to supporting polar or nonpolar media. We have studied the preparation of magnetic nanoparticles based on cobalt ferrite or magnetite, and stabilized the obtained product in an aqueous suspension. We found the optimal co-precipitation time for cobalt ferrite at 90 °C to be 2 h. Under such conditions the product exhibited the lowest amount of amorphous phase (46.2 %), average particle diameter 10.2 nm and a relatively high proportion of agglomerated particles (30 %). The product is therefore destabilized in an aqueous solution of polyvinylpyrrolidone K. The optimal co-precipitation time for magnetite at 90 °C is 30 min. After 30 min the product has no amorphous phase, average particle diameter is 6.8 nm and the proportion of agglomerated particles is low (3 %). The product is poorly stabilized because the proportion of agglomerated particles increases when the magnetite is re-dispersed in an aqueous solution of polyvinylpyrrolidone K. Magnetite prepared with the Massart method has a small amount of amorphous phase (4 %), average particle diameter is 6 nm and a low proportion of agglomerated particles (4.5 %) and is therefore well stabilized in an aqueous solution of polyvinylpyrrolidone KNanodelci kobaltovega ferita in magnetita imajo superparamagnetne lastnosti. Stabilne suspenzije superparamagnetnih nanodelcev imenujemo magnetne tekočine. Stabilne magnetne tekočine pripravimo z dodatkom surfaktantov v nosilni polarni ali nepolarni medij. Sintetizirali smo magnetne nanodelce kobaltovega ferita in magnetita ter dobljeni produkt stabilizirali v vodnem mediju. Določen je bil optimalen čas soobarjanja kobaltovega ferita pri 90 °C, in sicer 2 h. V tem času ima produkt najnižjo vsebnost amorfne faze (46,2 %), povprečno velikost delca 10,2 nm in delež neželenih aglomeratov pa je 30 %. Ko se delce kobaltovega ferita redispergira v vodi z dodanim surfaktantom, nastane destabilizirana suspenzija, katere vzrok je visok delež aglomeratov. Optimalen čas koprecipitacije magnetita pri 90 °C je 30 min. Takrat produkt nevsebuje amorfne faze, povprečna velikost delca je 6,8 nm, delež aglomeriranih delcev je 3 %. Produkt se nato redispergira v vodnem mediju z dodanim surfaktantom, kjer je magnetit slabo stabiliziran zaradi povečanja deleža aglomeratov med redisperzijo. Magnetit, pridobljen z metodo po Massartu, vsebuje Ž4 % amorfne faze, ima povprečno velikost delca Ž6 nm, delež aglomeratov 4,5 % in je zato odlično stabiliziran v vodni raztopini polivinilpirolidona KTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije