Modular Structures with Lone Electron Pair Cations

Datum: 12 mei 2014

Locatie: UAntwerpen - Campus Middelheim - Lokaal G0.10 - Middelheimlaan 1 - 2020 Antwerpen

Tijdstip: 16.30 uur

Organisatie / co-organisatie: Departement Fysica

Promovendus: Dmitry Batuk

Promotor: Dr. Artem Abakumov, prof. dr. Joke Hadermann

Korte beschrijving: Doctoraatsverdediging Dmitry Batuk - Faculteit Wetenschappen, Departement Fysica

Abstract: In this PhD research we explore the possibility to use lone pair cations (Pb2+ and Bi3+) to create new oxide materials with the so-called modular structures that can potentially demonstrate new functional properties, such as multiferroicity or frustrated magnetism. Modular, or fragment-recombination, structures are composed of modules or fragments (e.g. layers, blocks, rods) of prototype structures that are put together in an ordered fashion by various structure-building operations (chemical shift, intergrowth and twinning). We demonstrate that the lone electron pair cations are capable of acting as the "chemical scissors", isolating various transition metal modules. A number of materials were prepared using the solid-state and sol-gel synthesis techniques. The crystal structure of the new compounds has been determined using a combination of powder diffraction (laboratory and synchrotron X-ray and neutron powder diffraction) and electron microscopy (electron diffraction, high angle annular dark-field scanning transmission electron microscopy, annular bright-field scanning transmission electron microscopy). The structure solution of some families of modular structure discovered in this thesis also required application of sophisticated multidimensional crystallography. Beside the structure investigation, magnetic and electric properties of some compounds have been measured to analyze the effect of structural modularity on the properties of materials.