Anion deficient perovskites show promise for application as anode materials in solid oxide fuel cells.  The oxygen deficientperovskites Sr3SbO5.5, Sr2CaSbO5.5, Sr2BaSbO5.5, Sr3NbO5.5, and Sr3TaO5.5 all have the ideal cubic double perovskite crystal structure.  However, these compounds also have tolerance factors that are too small for octahedral tilting not to be present, as well as a large amount of diffuse scattering in their neutron powder diffraction patterns, both of which suggest a large amount of local disorder must be present.  The goal of this research is to determine how the local structures of these compounds differ from their long range average structures.  We are particularly concerned with understanding any short range ordering of oxygen vacancies that occurs, as this would directly affect their ionic conductivities.  We performed neutron total scattering experiments on each sample and used this data to obtain the pair distribution function (PDF) of each compound.  The PDF gives the distribution of inter-atomic distances in the material and allows us to determine the short and medium range order within the sample. 

Pair distribution function and its application to the determination of the local structure of Perovskite crystals

243rd National Meeting (2012)

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