Linear birefringence and dichroism in citric acid coated Fe3O4 magnetic nanoparticles

• Published in: Journal of magnetism and magnetic materials 2014-12, Vol.372, p.147-158
• Main Authors: Lin, Jing-Fung, Tsai, Chun-Chin, Lee, Meng-Zhe
• Format: Article
• Language: English
• Subjects: Birefringence; Co-precipitation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dichroism; Exact sciences and technology; Ferrofluid; Magnetic properties and materials; Magnetic properties of nanostructures; Nanocrystals and nanoparticles; Nanoparticle; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2014.07.064

To prepare highly dispersed water-based Fe3O4 magnetic nanoparticles (MNPs), we adopted the co-precipitation method and used citric acid (CA) as the surfactant. Via transmission electronic microscopy, dynamic light scattering, and X-ray diffractometry, we characterized the dispersibility and size of the products. Through two single-parameter experiments, including the pH value of suspension and the action of double centrifugations, the appropriate parameters׳ values were determined. Further, to produce CA coated MNPs with good magneto-optical properties as high retardance and low dichroism, the orthogonal design method was used to find the optimal parameters׳ values, including pH value of suspension after coating was 5, molar ratio of CA to Fe3O4 MNPs was 0.06, volume of CA was 40ml, and coating temperature was 70°C. Above all, the linear birefringence and dichroism of the best CA coated ferrofluid we produced were measured by a Stokes polarimeter as 23.6294° and 0.3411 under 64.5mT, respectively. Thus, the biomedical applications could be performed hereafter. •We examine pH changes about retardance/dichroism of citric acid coated ferrofluid.•We examine centrifugal action about dispersity of citric acid coated ferrofluid.•Dispersity of coated suspensions with different pH is investigated by DLS results.•Optimum combination and influence sequence obtained by Taguchi method is found.•Molar ratio of CA to Fe3O4 deeply influences the retardance and dichroism of FFs.