Physical Sciences Colloquia
The Physical Sciences Colloquia are intended for a broad audience – from undergraduate students to retired professors. The topics encompass the interests of all research groups in the School: from Applied Optics, through Astrophysics, Planetary Science and Forensic Imaging to Functional Materials Physics and Chemistry.
The colloquia are held on Wednesdays at 2 pm in the Ingram Lecture Theatre (ILT) unless otherwise specified. The programme is constantly updated. Click on the speaker’s name and the talk’s title for biographical information/contact details and an abstract, respectively.
All our colloquia for this term will be on our Events Calendar which we regularly update when we have a confirmed speaker so make sure to check back regularly! You can also have a look at speakers for our present term by clicking on their entry below:
9 October 2019 – Professor Roger Whatmore, Department of Materials, Imperial College, London NB: Please note this event will take place at 1pm
Title: “Liquid Exfoliation and Piezoresponse Force Microscopy Investigations of Ferroelectric Aurivillius Phase Nanosheets”
Abstract: Ferroelectrics form an attractive class of materials for many applications, such as in harvesting ambient energy via piezoelectric or pyroelectric effects in portable electronics or as memory elements for data storage, and ultra‐miniaturization is a key aspect of this. Thus, progress in the synthesis and understanding of their fundamental properties of ferroelectric materials at nanoscale (sub 10 nm) dimensions is important in both pure and applied research.
Aurivillius‐phase (AuP) ferroelectrics (general formula (Bi2O2)2+(Am‐1BmO3m+1)2‐) have structures consisting of layers of perovskite structure (m blocks) interleaved between fluorite‐like (Bi2O2)2+ layers. Here, we report the exfoliation of AuP SrBi2Nb2O9 (SBN ‐ m=2), Bi4Ti3O12 (BTO ‐ m=3) and Bi5Ti3Fe0.5Co0.5O15 (B5TFCO m=4) crystallite ‘flakes made by molten‐salt synthesis, and the investigation of the structures, ferroelectric and electrocatalytic properties of the exfoliated materials. PFM experiments support the ability for room temperature ferroelectricity to exist and switch in nano‐structured B5TFCO flakes as thin as 2.4 nm, which corresponds to a half
unit‐cell thickness for this structure.
This indication that ferroelectricity can survive at sub‐unitcell dimensions is significant from a fundamental point of view and important for practical applications of piezoelectrics and ferroelectrics in future miniaturized electronic devices.
9 October 2019 – Dr Lynette Keeney, Tyndall National Institute, University College CorkNB: Please note this event will take place at 1:45pm
Title: “Developing Multiferroic Aurivillius Phase Materials for Future Data Storage Technologies”
Abstract:The remarkable growth of the internet means that by 2025, the data created worldwide will be equal to a stack of DVDs that could reach the moon 23 times or circle Earth 222 times! Existing data storage solutions, based on either electric or magnetic information stored separately in single-bit devices, are already struggling to match the demand for data.
Considering this, it is now widely appreciated that technologies that can simultaneously combine electric and magnetic storage will permit up four-times or more increase in the amount of information that can be stored. However currently, no such devices exist because the materials needed for this technology- so-called multiferroics which work at room temperatures- are not only extremely rare but also remain to be proven to work at the dimensions required – typically around 10 nanometres- about 6000 times thinner than a human hair.
In this seminar, I will present the development of a rare example of such a multiferroic material system, Aurivillius phase Bi6TixFeyMnzO18 that exhibits ferroelectricity, ferromagnetism and magnetoelectric switching within the same structure at room temperature. The importance of rigorous analysis of sample purity before one can be confident that a material is truly a single-phase multiferroic will be presented. I will discuss why the presence and location of manganese within the structure is key to its ferromagnetic behaviour. Finally, I will present the recent progress in the optimisation of these materials at <10nm dimensions for potential data storage applications.