Effect of tetramethylammonium hydroxide on nucleation, surfacemodification and growth ofmagnetic nanoparticles.
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2012
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Nanoparticles of magnetite (Fe3O4) were obtained by reacting ferric chloride with sodium sulphite, through the reductionprecipitation
method. The effects of adding tetramethylammonium hydroxide (TMAOH) during or after the precipitation of the
iron oxide were studied in an attempt to obtain well-dispersed magnetite nanoparticles. Accordingly, the following experimental
conditions were tested: (i) precipitation in absence of TMAOH (sample Mt), (ii) the same as (i) after peptizing with TMAOH
(Mt1), (iii) TMAOH added to the reaction mixture during the precipitation of magnetite (Mt2). Analyses with transmission
electron microscopy (TEM), X-ray diffraction, M¨ossbauer spectroscopy, attenuated total reflectance Fourier transform infrared
spectroscopy (ATR-FTIR), zeta potential, and magnetization measurements up to 2.5 T revealed that magnetite was normally
formed also in the medium containing TMAOH. The degree of particles agglomeration was monitored with laser diffraction
and technique and inspection of TEM images. The relative contributions of N´eel and Brownian relaxations on the magnetic heat
dissipation were studied by investigating the ability of suspensions of these magnetite nanoparticles to release heat in aqueous
and in hydrogel media. Based on ATR-FTIR and zeta potential data, it is suggested that the surfaces of the synthesized magnetite
particles treated with TMAOH become coated with (CH3)4N+ cations.
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ANDRADE, A. L. et al. Effect of tetramethylammonium hydroxide on nucleation, surfacemodification and growth ofmagnetic nanoparticles. Journal of Nanomaterials, v. 2012, p. 1-10, 2012. Disponível em: <https://www.hindawi.com/journals/jnm/2012/454759/>. Acesso em: 20 abr. 2017.