Speaker: Prof. J. Paul Attfield, Centre for Science at Extreme Conditions and School of Chemistry, University of Edingburgh, United Kingdom

Date: 2011-10-13

Time: 14:15

Place: Chemistry Center, Lecture Hall B, Lund, Sweden.

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Electronic metal oxides often adopt simple inorganic structure types such as perovskite, but with subtle superstructures that result from coupling of spin, orbital and charge degrees of freedom. Further, far-from-equilibrium, materials are available by quenching from high pressure and temperature conditions. Recent results for the high pressure phases MnVO3, and BiNiO3 which shows a remarkable intermetallic valence transition leading to colossal negative thermal expansion at ambient conditions, will be presented.

Substitution of oxide by nitride enables oxynitride perovskites of high valent transition metals to be stabilised, and colossal magnetoresistances (CMR) at low temperatures have been discovered in EuNbO2N and EuWON2. The anion ordering principles, deduced from neutron diffraction, and predicted local structures for AMO3-xNx perovskites will be discussed.