Dr Siegbert A. Schmid, Senior Lecturer, School of Chemistry, The University of Sydney.
Brief summary of expertise and significant research achievements:
Dr Schmid's research on modulated structures and on chemical systems, e.g. ceramic
materials, forming modulated structures is at the forefront of the
respective research fields. He has been able to solve a number of problem
structures of compounds that have been under investigation for up to
thirty years, e.g. the structures of Y7O6F9 and Zr9N8F11, which were
at the centre of the Vernier concept developed in the 1970s. It is a
combination of the requisite synthetic skills for synthesising these
compounds and growing single crystals, along with the expertise in dealing
with modulated structures, which has made these significant contributions possible.
Schmid has been able to demonstrate that the modulated structure approach, in particular for composite modulated structures, is extremely useful to refine and describe structures in non-stoichiometric solid solutions, especially wide-range non-stoichiometric solid solutions. Modulated structures of compounds that belong to the same non-stoichiometric solid solution adopt the same modulation functions and, therefore, despite differences in the real 3-D structure, are equivalent from a higher-dimensional point of view. The significance of this discovery is that all structures in an incommensurate modulated non-stoichiometric solid solution can be described with a single set of modulation functions. Consequently only one good quality structure refinement will be required to adequately describe the whole system.
International linkages:
V. Petricek, M. Dusek - Institute of Physics, Prague, Czech Republic
(Refinement of modulated structures; testing and development of JANA).
Prof. N. Ishizawa, Nagoya Institute of Technology, Japan (Study of fluorite related modulated structures using synchrotron radiation)
Website:
http://www.chem.usyd.edu.au/about/staff_schmid.html
Relevant publications:
R. L. Withers, S. Schmid & J. G. Thompson, Prog. Solid State Chem. 26, 1 - 96 (1998).
Compositionally and/or displacively flexible systems and their
underlying crystal chemistry.
C. D. Ling, R. L. Withers, S. Schmid & J. G. Thompson, J. Solid State Chem.
137, 42 - 61 (1998).
A review of bismuth-rich binary oxides in the systems Bi2O3-Nb2O5,
Bi2O3-Ta2O5, Bi2O3-MoO3, Bi2O3-WO3.
S. Schmid, Acta Crystallogr. B54, 391 - 398 (1998).
The yttrium oxide fluoride solid solution described as a composite modulated
system.
C. D. Ling, J. G. Thompson, R. L. Withers & S. Schmid, J. Solid State Chem.
142, 33 - 40 (1999).
Modelling and Rietveld-refinement of the crystal structure of Bi4Ta2O11
based on that of Bi7Ta3O18.
C. D. Ling, S. Schmid, R. L. Withers, J. G. Thompson, N. Ishizawa & S. Kishimoto,
Acta Crystallogr. B55, 157 - 164 (1999).
Solution and refinement of the crystal structure of Bi7Ta3O18 using
single-crystal X-ray and powder neutron diffraction data.
C. D. Ling, J. G. Thompson, R. L. Withers & S. Schmid, Acta Crystallogr.
B55, 306 - 312 (1999).
Structures of Bi14WO24 and Bi14MoO24 from neutron powder diffraction data.
S. Schmid, J. G. Thompson, R. L. Withers, C. D. Ling, N. Ishizawa & S. Kishimoto,
Acta Crystallogr. B55, 313 - 320 (1999).
The crystal structure of Ca7Zr7Ta6O36 refined using synchrotron radiation data.
S. Schmid, R. L. Withers, D. L. Corker & P. Baules, Acta Crystallogr. B56,
558 - 564 (2000).
Towards a unified description of the AMOB2O5 (A = K, Rb, Cs, Tl; M = Nb, Ta)
family of compounds.
R. L. Withers, S. Schmid, L. Noren, Y. Tabira & J. G. Thompson, Ferroelectrics
250, 47 - 52 (2001).
Phase analysis, local crystal chemistry and the crystallography of
incommensurate crystal phases.
S. Schmid, T. Wagner & M. Adam, Z. Kristallogr. Suppl. 19, 96 (2002).
Strukturlösung und -verfeinerung von KNbOB2O5 - einer kommensurabel modulierten
Struktur.
S. Schmid (2002). Habilitationsschrift (Habilitation Thesis), University of
Tübingen.
Early Transition Metal Compounds with Modulated Structures.
T. Wagner, S. Schmid & V. Petrícek, Acta Crystallogr. A58 (Suppl.) C187 (2002).
Teaching Modulated Structures - A Project-based Approach.
S. Schmid, Z. Anorg. Allg. Chem. 628, 2210 (2002).
Ein Beitrag zu den modulierten Strukturen von Nb2Zrx-2O2x+1 (7.1 = x = 10.3)
und verwandten Phasen.
