NANOFERRO · Towards size effects in nanosized ferroelectrics - fabrication of nanocrystals by self-assembling methods
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2005-03-01 → 2006-02-28
- EU contribution
- €40,000
- Participants
- 1
- Scheme
- ERG
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Results in brief
Final Activity Report Summary - NANOFERRO (Towards size effects in nanosized ferroelectrics - fabrication of nanocrystals by self-assembling methods)
The main goal of this work was the preparation of nanosized ferroelectric crystals by self-assembling methods. These approaches offered inexpensive fabrication of structures with size below 100 nm, and several non-conventional routes were applied to fulfil this task. This project focussed on the most important materials for future devices, such as barium titanate (BaTiO3), BiFeO3, PbTiO3 and lead zirconate titanate (PZT) that possessed perovskite crystallographic structures. They were expected to play an important role in fields such as sensors, actuators, memory devices and optics. The most successful strategy based on the concept of structural and microstructural instability of ultrathin films was carefully studied as part of the project. There was already several evidence that the properties of nanostructures were closely related to misfit dislocations caused by lattice mismatch. Therefore, the suggestion that the formation process of islands could also be defect or strain-dependent was experimentally investigated. The broad choice of substrate and PZT nanocrystal composition provided lattice mismatch ranging between 8 % and 0.2 % approximately. The formation process of nano-islands was carefully investigated by atomic force microscopy, electron microscopy and X-ray diffraction. Moreover, a multi-step deposition procedure was introduced in order to laterally control the crystals' dimension. The other route of ferroelectric nano-powders preparation used mechano-chemical synthesis. In contrast to the classical solid-state reaction, high energy milling reduced the particle sizes and increased in the contact area of reactant particles; thus, the reaction could proceed without diffusion through the product layer, i.e. the ferroelectric formation occurred at lower temperatures. The X-ray diffraction demonstrated the perovskite structure of the powder directly after the room temperature synthesis. In addition, it was found that: 1. the powder consisted of loosely packed grains with a broad size distribution, between a few nm and 45 nm; 2. the grains of sizes larger than about 30 nm exhibited well-developed crystalline structure; and 3. the Raman lines of nanopowder exhibited a conspicuous broadening in comparison to Raman lines of the bulk material and their frequencies shifted.
Data: CORDIS, © European Union
Project objective
Nanotechnology is expected to have a big impact on most of our life. Nanostructred materials become more and more important in various fields such as nanoelectronics, information storage technology etc. At the nanometre scale, i.e. 1-100 nm, material properties are clearly size-dependent and new properties are expected. Among functional materials nanoscale ferroelectrics can have a major role because they can be applied in different fields such as sensors, actuators, memory devices and optics. However they cannot be applied to nanometre scale devices before the influence of the lateral size on physical properties will be clarified.In order to find answer for the problems there is a need to have good quality nanoscale structures. It is a challenge to fabricate such structures in this range using both lithography ('top-down' approach) and self-assembling and self-patterning methods ('bottom-up' approach). Whereas conventional lithographic systems work usually with a resolution of about 100 nm the bottom-up approaches allow the inexpensive fabrication of structures with size of 10-20 nm. The main goal of the work is preparation of nanosized ferroelectric crystals by self-assembling methods. Successful strategies and routes have been developed to synthesize nanoscale materials of numerous simple systems such as semiconductors or metals.Complex systems such as ferroelectric oxides are not yet systematically addressed, despite of the possibility of discovering new materials with unique properties. Physical route based on the concept of microstructural instability of ultra-thin films and chemical routes will be applied to obtain different perovskite crystals. A good quality of nanostructures that lateral dimension can be tuned in nanometre range is expected to fabricate and in future this will allow investigating structure-property relations (e.g. by transmission electron microscopy and piezoresponse force microscopy) and solve 'size effects' problem.
Original text from CORDIS.
Participants
- POZNAN UNIVERSITY OF TECHNOLOGY · POZNANCoordinatorCity levelPoland
Links
Data: CORDIS, © European Union