Magnetic nanoparticles that can be heated up by an external magnetic field are highly demanded for biomedical applications, e.g. hyperthermia treatment for the destruction of cancer cells, as well as in engineering tasks like the fast curing of adhesives for the joining of non-conductive components. Standard magnetite (Fe3O4) nanoparticles however show a high Curie temperature of > 500°C, which means they "switch off" only at very high temperatures, which can result in damages of the surrounding tissue or matrix material. The research group of Prof. Dr. Georg Garnweitner, Institute for Particle Technology and Laboratory for Emerging Nanometrology (LENA), was able to synthesize and trace the growth process of Mn(1-x)Zn(x)Fe2O4 nanoparticles in a novel shamrock-like shape that show a Curie temperature depending on the composition that can be tuned between 170 - 420°C, which makes them highly promising for a number of applications.
The nanoparticles were synthesized in a nonaqueous sol-gel process and were shown to adopt their unique shamrock-like shape by a mechanism of oriented attachment, which means that small individual units attach to each other and fuse into a larger crystal. The formation mechanism was clarified by different methods including small-angle X-ray scattering (SAXS) in joint investigations with the Institute of Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology.
Publication:
I.-C. Masthoff, A. Gutsche, H. Nirschl, G. Garnweitner
Oriented attachment of ultra-small Mn(1−x)ZnxFe2O4 nanoparticles during the non-aqueous sol-gel synthesis
CrystEngComm (2015).
DOI: 10.1039/C4CE02068E
Contact:
Prof. Dr. Georg Garnweitner
Institute for Particle Technology
Laboratory for Emerging Nanometrology
Technische Universität Braunschweig
Volkmaroder Str. 5
D-38104 Braunschweig
Phone: (+49)531 391 9615
Email: g.garnweitner@tu-braunschweig.de
http://www.ipat.tu-bs.de/