Contact person: Tobias Preller
The continuous desire for smaller and more efficient electronical devices evokes an inevitable necessity for materials with specialized properties. Besides optimized high performance materials with a complex composition, multifunctional composites are of increased significance. Merging a variety of nanosized materials in one composite leads to combined properties of the respective particles or enables the generation of utterly new characteristics, which holds a huge potential for technical improvements. Currently, Exchange-Spring magnets, permanent magnets with high magnetization made of hard and soft magnetic materials as well as Multiferroics, which comprise ferroelectric and superparamagnetic properties have been realized.
As an alternative to the currently complex manufacturing processes of those composite materials, the combination of pre-fabricated building blocks including the specific selection of materials with tailored characteristics is attempted. Thereby, nanoparticulate building blocks are synthesized with particle sizes of below 20 nm. Frequently used materials are alumina Al2O3, barium titanate BaTiO3, iron oxide FexOy, iron platinum FePt, titania TiO2 and zirconia ZrO2.
The avoidance of agglomeration processes in the nanoparticulate medium in order to create homogenous composites with uniformly distributed nanoparticles of various materials is a crucial challenge. For the deposition of the particles wet processing techniques are used, which lead to the desired multifunctional thin films.
In the branch Nanomaterials, the preparation of those nanocomposites is determined using pre-fabricated nanoparticles in a three-step approach. Compared to complex manufacturing methods such as the in-situ synthesis, where various materials are combined on the atomic level, the novel approach enables a high control over the product morphology and the selection of individual phases of the nanoparticulate building blocks, while avoiding undesired side products.
Abbildung 2: Die TEM-Aufnahme eines Dünnschicht-Nanokomposits zeigt die gute Durchmischung zweier nanopartikulärer Bestandteile.
Im Forschungsbereich Nanomaterialien wird die Herstellung solcher Nanokomposite aus zuvor synthetisierten Nanopartikeln mit Hilfe eines Drei-Schritt-Verfahrens untersucht. Dieses bietet dabei deutliche Vorteile gegenüber komplexeren Methoden, wie beispielsweise der oftmals eingesetzten in situ-Synthese, in der die molekularen Vorstufen der Bausteine und somit die einzelnen Materialien bereits auf atomarer Ebene miteinander vereint werden, jedoch nur eine geringe Kontrolle über die entstehende Produktmorphologie, sowie über die gebildeten Nebenprodukte und keine willkürliche Auswahl individueller Phasen möglich ist.