A homologous series of structures on the surface of SrTiO3
Strontium Titanate ( SrTiO3 ): Strontium Titanate is a complex metal oxide of strontium and titanium. At room temperature it exists in the cubic form, but transforms into the tetragonal structure at temperatures less than 105K. It is an excellent substrate for epitaxial growth of high-temperature superconductors and many oxide-based thin films. Its monocrystals can be used as optical windows and high-quality sputter deposition targets. Strontium Titanate has the ability to split water into hydrogen and oxygen with sunlight and its potential for use in electronic devices. Strontium titanate is seeing increasing interest in fields ranging from thin-film growth to water-splitting catalysis and electronic devices.
A homologous series of structures on the surface of SrTiO3
An international team of scientists led by Dr Martin Castell of Oxford University’s Department of Materials used a variety of techniques including scanning tunneling microscopy (STM) to directly ‘see’ the arrangement of surface atoms of various materials.
Dr. Castell says, “In most materials, when you create a surface, the top layer of atoms rearrange to different positions from those in the rest of the material. This rearrangement of atoms is usually locked into a particular configuration that will minimise the surface energy. However, this is not the case for the surface of strontium titanate that we have been studying. This surface forms a whole family of different structures. Chemists would call these structures a homologous series – something that is routinely observed in the bulk of crystals, but not until now on the surface.” These homologous series of structures on the surface of SrTiO3 could be very important in order to build new kinds of nanoelectronic devices or to grow thin films.
Also according to the researchers the techniques they have developed could make it possible to predict the surface structures of other oxides. “We have needed to use many different sophisticated experimental and theoretical approaches to solve this problem,” said Dr Castell. “Our aim is to continue to work closely with our collaborators at Northwestern University in the US to solve related materials problems.”
Source: http://www.ox.ac.uk/media/news_stories/2010/100215.html
February 15, 2010