The beauty of the nano world
Grain boundary in yttrium-aluminium garnet
An image of an yttrium-aluminium garnet (YAG) grain boudaries. Garnets are are an important class of minerals, found everywhere in the earth crust, and this particular piece of test crytstal was used to understand how impurities diffuse along 'grain boundaries' (the junction area between two pieces of crystal).
Single Si atom impurity in graphene
Graphene, the 'wondermaterial' needs no introduction: it is only one atom thick and boasts a host of exciting properties. SuperSTEM microscopes allows researchers to see each and every single one of those atoms and detect, as in this image, when a single Si atom is introduced in the lattice as a doping species. Si is heavier and it appears brighter in the images.
Anti phase boundary in Bi2Te3
HAADF STEM image (false coloured) showing an antiphase boundary in a Bi2Te3 thin film. The defect originates from the interface of the Bi2Te3 film and inclusions of superconducting FexCu1−xSe which are epitaxially oriented with respect to the film.
MAADF image of grain boundary in Ba6-3xNd8+2xTi18O54 (BNT)
BNT is a highly important material in mobile phone communication where it is used as resonator/filter in base stations. Adjusting the material properties of this material by varying composition necessitates a detailed understanding of the atomic structure and changes with composition. Atomic resolution imaging allows exact atomic positions to be determined while spatially resolved, atomic resolution EELS measurements give access to the elemental distribution at lattice positions.
Ripples in suspended Graphene
Spatial frequency filtered HAADF image to show ripples in suspended graphene. Black ‘beads’ are the centres of 'benzene' rings. The bead-strings gave a separation of 0.21 nm, the colour coding is chosen so that the atoms on tops and in throughsof ripples appear yellow and in the flanks bluish. The ripple amplitude is ~0.5 nm and their ‘wavelength’ ~5 nm
Suspended Graphene with 'dislocation' dipole
Atomic structure of suspended mono-layer graphene, containing a separated ‘dislocation’ dipole, which consists of a shuffle (bottom) and a glide (top) segment. The model structure is overlaid. These dipoles have been predicted by theory. In contrast to semiconductors, where the shuffle segment in sessile and the glide segment is mobile, in graphene the shuffle segment is the mobile, ‘gliding’ segment; lattice resolution HAADF image, low-pass filtered
Atomic structure of suspended graphene, one mono-atomic layer of graphite (just like chicken wire-see ball and stick model), incorporating carbon ad-atoms on C-C bonds and a vacancy; lattice resolution HAADF, low-pass filtered
Cellular Structure (stained)
Human hepatic ferritin mineral core
Alignment and classification of 750 particles. The tetrad view is still very clear, but less common than in the entire image set. Scale bar is 10nm. Color insert shows single particle 3D reconstruction. (Publication)
Au atoms in Si nanowire
Sum of seven aligned HAADF-STEM images of an intrinsic Si nanowire showing impurities trapped at a twin defect and bulk impurities.
The unique optical sectioning properties of aberration corrected STEM was used to acquire HAADF images at various depths through a Si nanowire so that the 3D distribution of Au atoms could be determined for the first time.
imaged at 80 kV (left). Small gold clusters on carbon appear less mobile (and thus sharper in the image) at low kV (right).
Nanotoxicity: what is in the air you breath?
This image shows particles of magnesium oxide captured from the smoke of burning magnesium metal. It was recorded at the SuperSTEM facility at Daresbury Laboratory on an electron microscope that has compensation for the defects in its lenses. It was collected on a digital camera, and has been Fourier filtered to remove artefacts from the camera. The diameter of the field of view is approximately 300nm.
The structure of these particles produced in a simple plume of smoke are a reminder that there is a hidden world beyond our everyday perception. In the past few decades our ability to study and manipulate materials at the "nanometre" scale (a billion times smaller than a metre) has immensely improved. Tailor-made particles of this size are being produced for use in many applications including medical diagnostics and treatments. However, methods to determine the safety of such materials are only beginning to be developed. There is a tremendous potential for such technology, but only if the risks are rigorously assessed.