Research Profile - Department of Materials Science and Metallurgy ...

Erica Bithell
Daphne Jackson Research Fellow
MA University of Cambridge
PhD University of Cambridge
+44 (0) 1223 334566
egb10@cam.ac.uk
www-hrem.msm.cam.ac.uk/
Electron Microscopy and Crystallography
My main research interest is applying transmission electron
microscopy and electron crystallography to the understanding of
pattern and structure in the world around us.
In September 2007 I resumed my research career after a break
caring for my young family. My earlier interests included work
on high-spatial-resolution characterization techniques for a
variety of inorganic materials, ranging from heterostructures for
microelectronic devices to oxide- and metal-particle catalysts.
Examples of this research are given in the publications cited
below.
Precession electron diffraction
With the development of commercially available equipment for
precession electron diffraction, crystal-structure determination in
the electron microscope has become possible with an accuracy
which could previously be obtained only using X-rays. I am now
building on my earlier experience by developing applications of
precession electron diffraction to materials containing organic
components, with a particular interest in pharmaceutical crystals.
Pharmaceutical materials
Even the most basic crystallographic details remain unknown
for many pharmaceutical compounds, with little being recorded
beyond their crystalline form. Many of these materials can form a
number of co-existing phases or polytypes, precluding any work
on single crystals and limiting the application of X-ray diffraction.
Transmission electron microscopy and diffraction, by contrast,
are well suited to work with mixed systems of this type. Different
structures are readily distinguished, often simply because each
variant has a characteristic morphology. The aim of current
research is to collect and analyse precession electron diffraction
data from such materials in conjunction with information from
X-ray diffraction and molecular chemistry, to establish at least the
unit-cell sizes and lattice types for these compounds, to extend
this to more detailed crystal structure determination and to
develop a protocol for carrying this out as a routine procedure.
EG Bithell & WM Stobbs, “Composition determination in the GaAs/(Al,Ga)
As system using contrast in dark field transmission electron microscope
images” Philos. Mag. A 60, 39–62 (1989).
EG Bithell & WM Stobbs, “III-V ternary semiconductors: the choice of
appropriate characterization techniques” J. Appl. Phys. 69, 2149–2155
(1991).
EG Bithell, RC Doole & MJ Goringe, “On the extraction of high quality
data from real-time transmission electron microscopy experiments”
Ultramicroscopy 56, 172–183 (1994).
Precession electron diffraction pattern from Cr
ethylenediphosphonate (P6cc, a = 1.311 nm, c = 0.926 nm)
8 Research Profile