Organically linked iron oxide nanoparticle supercrystals with exceptional isotropic mechanical properties
Prof. Gerold A. Schneider
Head of Institute of Advanced Ceramics, Hamburg University of Technology, Denickestr. 15, 21073 Hamburg, Germany
– All Welcome –
It is commonly accepted that the combination of nanosize and elongated mineral constituents in biological materials is the main reason for their exceptional mechanical properties as compared to their rather weak mineral and organic constituents. Here we show that the self-assembly of spherical iron oxide nanoparticles in supercrystals linked together by a thermally induced coupling reaction of oleic acid or oleyl phosphate molecules leads to nanocomposites with exceptional microbar bending modulus and strength. Because the used nanoparticles are spherical, the shear load transfer mechanism for elongated particles is not responsible for the high strength. Instead, it is the covalent backbone of the linked organic molecules, which dominates the mechanical properties, leading to also a very high nanohardness. The self-assembly of the nanoparticles as well as mechanical properties of the supercrystals are discussed.
Dr. Schneider joined the faculty of the TUHH in 1994. He has published more than 150 scientific papers dealing with the fracture of brittle materials (structural ceramics, ferroelectric ceramics and piezoelectric actuators, teeth, nanocomposites) and the development of lead free ferroelectric ceramics, organically linked supercrystals and ceramic photonic crystals. He holds two German patents and developed a commercial mechanical testing device together with the company Exact (Hamburg). Dr. Schneider spent a sabbatical as Adjunct Professor at the University of California, Santa Barbara in 1999 and as a Visiting Professor at the University of Sydney in 2007. He was awarded with the Heinz-Maier-Leibnitz-prize of the German Research Foundation and the German Federal Minister of Education and Science in 1992 and is an academician of the World Academy of Ceramics. In 2009 he was awarded with the Sir Thomas Kay Sidey Visiting Professorship of the University of Otago, New Zealand. Currently he is the coordinator of the TUHH – Research Centre “Product Oriented Materials Development” and the speaker of the collaborative research centre SFB 986 “Tailor-Made Multi-Scale Materials Systems – M3” funded by the German Research Foundation.
For more information, please contact Prof Jay Kruzic.