I got pure phase of magnetite nanoparticles, checed by powdered X- ray diffraction... Even so they were coated, after probe of dispersion by sonication they become brown! The synthesis was well made under Argon flow, DI water and ammonia were degasiefied before to avoid additional access of oxygen, an environment is keeping about10 pH, sonication makes with cooling at the same time...
Look forward to hearing from you!
What was the original colour of your magnetite nanoparticles in solid? One possible cause is that the nanoparticles partly dissolved in the solution to producing Fe2+ and/or Fe3+ ions which will give yellow- or brownish colour. Also, it is impossible to avoid oxidation of the magnetite nanoparticles in water under your experimental conditions, particularly if the sonication lasted for a sufficiently long time.
What was the original colour of your magnetite nanoparticles in solid? One possible cause is that the nanoparticles partly dissolved in the solution to producing Fe2+ and/or Fe3+ ions which will give yellow- or brownish colour. Also, it is impossible to avoid oxidation of the magnetite nanoparticles in water under your experimental conditions, particularly if the sonication lasted for a sufficiently long time.
George thank you for feedback. Original colour was black and the phase checked if not contain impurities.... Magnetite was dried in vacum oven after synthesis and afterwards tried disperse in buffer and glycol. Even so after few seconds of sonification solution become brown...
Dear Zuzanna Madam,
I thinks it's common to have brown coloration of magnetite nanoparticles suspension.
It depends upon treatment used in synthesis and coating.
Plz refer following paper.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3123420/
I agree with George Zheng Chen 's opinion. Sonication also separates the aggregated particles. When you have fine nano particles, the colour changes because of higher and higher S/V ratio which contributes to higher no. of loosely bounded surface lattice sites that changes the scattering and hence the change in color.
Checked one more time, what if the suspension (dextran coated magnetite nanoparticles) become dark brownish even without sonication (just after probe "shaking" or light stirring)?
I shall mention that when very fine carbon particles are dispersed in water at a sufficiently low concentration, the solution could also be brown- or yellowish.
Thank you Gentlemen! I appreciate whole effort so I am going to check everything step by step once again. Best wishes!
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