Perovskites under extreme conditions: pushing the limits of neutron diffraction [article]

Mara Capone, University Of Edinburgh, University Of Edinburgh, John Loveday, Malcolm Guthrie
The application of hydrostatic pressure and temperature are effective methods for manipulating and correlating crystal structures and physical properties of materials. Volume, interatomic distances, chemical bonds, local atomic coordination are all strongly altered by pressure and temperature, which can either distort or symmetrise the structure and cause the alteration of the crystal symmetry with huge consequences on the physical properties. High Pressure (HP), in particular, can induce
more » ... r, can induce significant structural and physical changes and can be used to explore structural-property relationships in a huge variety of materials. Perovskite compounds are excellent candidates for HP investigations owing to remarkable changes in their structural, electrical and magnetic properties in response to a variation of the chemical composition x or volume of the material. Diverse crystal structures and physical properties are found in the perovskite family, which can be controlled by the application of pressure and/or temperature. Among the broad spectrum of experimental techniques, neutron-powder diffraction offers several advantages for in situ investigation under extreme conditions of perovskite materials. Neutron diffraction provides the ability to map the relative positions of atoms and their structural changes down to the nanometre length-scale. The complex dependence of the coherent neutron scattering cross section on the atomic number Z of the scattered material enables diffraction comparison between neighbouring elements in the periodic table and isotopes, and a higher sensitivity to light elements such as hydrogen or oxygen in the presence of heavier atoms. The primary aim of this thesis investigates perovskite oxides and focuses on their structural and physical characterisation under the application of hydrostatic pressure and/or temperature. Perovskites exhibit physical properties utilised in several technological fields, from the magnetoresistence of lanthanum manganites, to the catalytic activity of cobalt-based comp [...]
doi:10.7488/era/463 fatcat:qvlih4ni6nfrvctkbqsvrlygam