495 KB13 KB198520252011Drmota, AnaŽnidaršič, Andrejštevilka:3letnik:41str. 202-204ISSN:0352-9045COBISSID:35785733URN:URN:NBN:SI:doc-OVELQYTNenStrokovno društvo za mikroelektroniko, elektronske sestavne dele in materialeInformacije MIDEMmagnetic nanoparticlesmagnetni nanodelcimicroemulsion methodmikroemulzijska metodananotehnologijasilicasilicijev dioksidsilikaželezov oksidSynthesis and characterization of silica coated magnetic nanoparticles|Magnetic (\gamma-Fe_2O_3) nanoparticles coated with silica (SiO_2) and a narrow particle size distribution were prepared in microemulsion system: water/(SDS+1-butanol)/cyclohexane. The influence of the concentration of reactants in aqueous phase, the temperature of reaction, the pH value during the precipitation of hydroxides and the type of surfactant, on the nature of \gamma-Fe_2O_3 nanoparticles were investigated. The thickness of SiO_2 shell was carefully controlled by the amount of tetraethoxysilane (TEOS) added to the microemulsion after the precipitation step. Prepared uncoated and coated \gamma-Fe_2O_3 nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffractometry (XRD) and specific surface area measurements (BET). The specific magnetization (DSM-10, magneto-susceptometer) of the prepared samples was also measured. The specific magnetization of the \gamma-Fe_2O_3 nanoparticles depended on their size, ranging from 14 to 49 Am^2/kg. The specific magnetization of coated \gamma-Fe_2O_3 nanoparticles sharply decreased due to the non-magnetic nature of SiO2 layerMagnetne (\gamma-Fe_2O_3) nanodelce s silikatno (SiO_2) prevleko smo sintetizirali v mikroemulzijskem sistemu: voda/(SDS+1-butanol)/cikloheksan. Raziskali smo vpliv koncentracije reaktantov vodne faze, temperature reakcije, pH vrednosti soobarjanja hidroksidov in tipa surfaktanta na naravo \gamma- Fe_2O_3 nanodelcev. Debelino nanosa SiO_2 smo kontrolirali s količino dodanega tetraetoksisilana (TEOS) v mikroemulzijo po končani reakciji soobarjanja. Neoblečene in s SiO_2 oblečene \gamma-Fe_2O_3 nanodelce smo karakterizirali s transmisijskim elektronskim mikroskopom (TEM), rentgensko praškovno difrakcijo (XRD) in merjenjem specifične površine delcev (BET). Pripravljenim vzorcem smo merili specifično magnetizacijo (M). V odvisnosti od velikosti delcev se je spreminjala od 14 do 49 Am^2/kg. Specifična magnetizacija oblečenih nanodelcev je močno padla zaradi nemagnetne narave SiO_2TEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaStrokovno društvo za mikroelektroniko, elektronske sestavne dele in materiale