Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

[PDF] http://dx.doi.org/10.3952/lithjphys.46408

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 46, 451–457 (2006)

MODIFICATION OF NANOCRYSTALLINE MAGNETITE BY MILLING
K. Mažeika^a, J. Reklaitis^a, G. Lujanienė^a, D. Baltrūnas^a, and A. Baltušnikas^b
^aInstitute of Physics, Savanorių 231, LT-02300 Vilnius, Lithuania
E-mail: kestas@ar.fi.lt
^bKaunas University of Technology, Donelaičio 73, LT-44029, Kaunas, Lithuania

Received 6 September 2006

Structural changes in the nanocrystalline magnetite induced by mechanical milling were studied by means of Mössbauer spectroscopy and X-ray diffraction. Magnetite coated with the surfactant layer and that without surfactant both placed into ethanol were milled using the planetary ball mill. Mössbauer spectra of samples were recorded at 16–300 K temperature. According to the results of the study, milled nanocrystalline magnetite can be divided into unaffected initial ferrimagnetic magnetite, superparamagnetic magnetite, and “intermediate” magnetite. The stoichiometry of samples was also evaluated.

Keywords: Mössbauer spectroscopy, nanoparticles, magnetite, ball milling, structural changes

PACS: 76.80.+y, 75.50.Tt, 81.20.Wk

NANOKRISTALINIO MAGNETITO MODIFIKAVIMAS MALANT
K. Mažeika^a, J. Reklaitis^a, G. Lujanienė^a, D. Baltrūnas^a, A. Baltušnikas^b
^aFizikos institutas, Vilnius, Lietuva
^bKauno technologijos universitetas, Kaunas, Lietuva

Nanokristalinis magnetitas etanolyje buvo malamas rutuliniu malūnu (Pulverisette 6). Magnetito sandaros pokyčiai buvo pastebimi Mesbauerio (Mössbauer) spektroskopijos ir Rentgeno (Röntgen) difrakcijos metodais. Viename iš malamų feroskysčių magnetito nanodalelės, kurių didumas pagal Rentgeno difrakcijos duomenis 16–17 nm ir kurios yra pagamintos cheminio nusodinimo metodu, prieš jas patalpinant etanolyje buvo padengtos paviršiaus aktyviąja medžiaga (oleino rūgštimi). Panaudojus Mesbauerio spektroskopiją, buvo įvertinami beveik nepaveikto ferimagnetinio (dalelių dydžiai 16–17 nm), paramagnetinio (susmulkintos dalelės iki 10 nm dydžio) ir tarpinio magnetito santykiniai kiekiai ir jų kitimas malant. Paveiktos susmulkintos nanokristalinio magnetito dalies kiekis po 6–10 valandų malimo viršijo nepaveikto magnetito kiekį. Nustatyta, kad feroskysčiui su aktyviąja paviršiaus medžiaga nepadengtomis dalelėmis malimo efektyvumas didesnis. Malant magnetitą etanolyje stechiometrijos kitimo (oksidacijos) nepastebėta.

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