Perovskites, especially ordered double perovskites (formula A2B'BO6) are susceptible to a wide variety of structural and electronic instabilities, resulting in a rich variety of ordered phases. We have a continuing research project on magnetic structures in osmium containing double perovskites which show many different structures and magnetic behaviours, as well as a variety of possible osmium valence states. Pb2ScOsO6 prepresents an interesting new chapter in this series as it contains two elements (Pb and Os) that have substantial spin-orbit coupling, and Sc3+ which has a very small ionic radius. This results (perhaps surprisingly) in the R-3 space group (tilt pattern a-a-a- in the Glazer notation) and the material undergoes two phase transitions at 110K and 50K both of which show features in the susceptibility. This combination of phase transitions likely results from a series of magnetic/structural instabilities that could easily be driven by either the Pb or the Os ions. In this experiment, We propose to determine the nature of these ordered phases.